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Ecological characteristics of the truncal skin mycobiome in acne and its association with doxycycline exposure
Hyun Ji Lee, Yong-Joon Cho, Nayan Jin, Piyapat Rintarhat, Won Hee Jung, Hei Sung Kim
J. Microbiol. 2026;64(1):e2511019.   Published online January 31, 2026
DOI: https://doi.org/10.71150/jm.2511019
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AbstractAbstract PDFSupplementary Material

Truncal acne significantly impairs quality of life yet remains underexplored relative to facial acne, particularly with respect to fungal ecology. The trunk represents a distinct cutaneous niche characterized by thicker epidermis, larger follicular units, and frequent occlusion, and harbors a high abundance of Malassezia species. In this study, we used internal transcribed spacer 2 (ITS2) amplicon sequencing to characterize the truncal mycobiome in patients with acne and in healthy controls and to compare fungal community features across doxycycline exposure groups. Although serial sampling was planned, seven participants contributed a single follow-up sample after doxycycline treatment, and only two participants contributed multiple follow-up samples sufficient for true within-subject longitudinal analyses; therefore, most analyses represent exposure-stratified cross-sectional comparisons rather than confirmed temporal change. At baseline, truncal acne lesions exhibited increased fungal richness and distinct community composition compared with controls. Acne lesions were more frequently enriched for Malassezia globosa, whereas healthy controls were dominated by M. sympodialis. Across doxycycline exposure groups, fungal communities remained Malassezia-dominant with substantial inter-individual variability. Doxycycline exposure was associated with partial and heterogeneous differences in Malassezia species composition without uniform normalization toward control profiles. Because only fungal sequencing was performed, bacterial–fungal interactions were inferred from prior literature and not directly measured. These findings indicate that truncal acne is associated with a distinct fungal community structure and highlight the need for integrated, longitudinal multi-omics studies to clarify treatment-associated microbial dynamics.

Development of tri-cistronic CLDN18.2 CAR-T cells incorporating PD-1/CD28 switch and cyclophilin A for enhanced solid tumor immunotherapy
Heon Ju Lee, Seo Jin Hwang, Eun Hee Jeong, Mi Hee Chang, Bu Yeon Heo, Jaeyul Kwon, Yoona Noh, Jihoon Nah
J. Microbiol. 2026;64(1):e2510017.   Published online January 31, 2026
DOI: https://doi.org/10.71150/jm.2510017
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AbstractAbstract PDFSupplementary Material

Chimeric antigen receptor (CAR)-T cell therapy holds significant potential for the treatment of solid tumors. However, immune suppression and tumor-specific barriers limit its application. Claudin 18.2 (CLDN18.2), a gastric lineage-specific tight junction protein highly expressed in gastric and pancreatic cancers, is a promising therapeutic target. In this study, we aimed to develop a next-generation tri-cistronic CLDN18.2-directed CAR-T cell platform that integrates a programmed cell death protein 1 (PD-1)/CD28 chimeric switch receptor with cyclophilin A (CypA). This platform sought to counteract PD-1–mediated immunosuppression and enhance T-cell activation and persistence. We generated CLDN18.2 CAR-T cells incorporating costimulatory inducible T-cell costimulator (ICOS) domains using lentiviral vector-based recombinant engineering. We further evaluated their cytokine release, cytotoxic activity, and safety profiles. In vitro, tri-cistronic CAR-T cells exhibited markedly increased interferon γ and tumor necrosis factor α secretion and enhanced cytotoxicity against CLDN18.2-positive gastric cancer cells compared with conventional CAR-T constructs. In vivo, these cells showed superior antitumor efficacy and sustained tumor regression without observable toxicity in xenograft gastric cancer models. Collectively, these findings demonstrate that the integration of PD-1/CD28 signaling and CypA within a tri-cistronic framework significantly reinforces CAR-T cell functionality and durability. This suggests strong clinical potential as a next-generation immunotherapy for solid tumors.

Sphingomonas degradans sp. nov. and Sphingomonas paludis sp. nov., isolated from the Han River and a wetland in South Korea
Seung-Tae Kim, Miryung Kim, Chang-Jun Cha
J. Microbiol. 2026;64(1):e2510010.   Published online January 31, 2026
DOI: https://doi.org/10.71150/jm.2510010
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AbstractAbstract PDFSupplementary Material

Two novel bacterial strains, designated CJ20T and CJ99T, belonging to the genus Sphingomonas, were isolated from the Han River in South Korea and a wetland in South Korea, respectively. Cells of both strains were Gram-stain-negative, aerobic, non-motile and yellow-pigmented. Strains were shown to grow optimally at 30˚C and pH 7 in the absence of NaCl on tryptic soy medium. Phylogenetic analysis based on 16S rRNA gene sequences showed that strains CJ20T and CJ99T belonged to the genus Sphingomonas and were most closely related to S. asaccharolytica Y-345T and Sphingomonas koreensis JSS26T with 97.87% and 97.58% 16S rRNA gene sequence similarities, respectively. Average nucleotide identity and digital DNA-DNA hybridization values of strain CJ20T with S. asaccharolytica Y-345T were 74.1% and 15.9%, respectively and those values of strain CJ99T with S. koreensis JSS26T were 73.9% and 15.6%, respectively. Both strains contained ubiquinone (Q-10) as the predominant respiratory quinone. The major polar lipids of strains CJ20T and CJ99T comprised phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, and sphingoglycolipid. The predominant fatty acids of both strains were summed feature 8 (C18:1 ω7c and/or C18:1 ω6c) and C16:0. Based on polyphasic taxonomic analyses, strains CJ20T and CJ99T represent novel species of the genus Sphingomonas, for which names Sphingomonas degradans sp. nov. and Sphingomonas paludis are proposed, respectively. The type strains are CJ20T (= KACC 23909 = JCM 37720) and CJ99T (= KACC 24077 = JCM 37956).

Effects of sequencing platforms on the profiling of root mycorrhizal communities in Pinus densiflora
Ki Hyeong Park, Seung-Yoon Oh, Shinnam Yoo, Yoonhee Cho, Ji Seon Kim, Chang Wan Seo, Chang Sun Kim, Young Woon Lim
J. Microbiol. 2026;64(1):e2509008.   Published online January 31, 2026
DOI: https://doi.org/10.71150/jm.2509008
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AbstractAbstract PDFSupplementary Material

Next-generation sequencing (NGS) has become a powerful and efficient tool for surveying mycorrhizal mycobiome diversity, surpassing classical methods in accuracy and throughput. Long-read NGS techniques are increasingly applied under the assumption that they provide better taxonomic resolution, yet their use often lacks a balanced evaluation against the established strengths and limitations of widely used short-read NGS technologies. This study compares Illumina MiSeq and PacBio Sequel platforms in analyzing the mycorrhizal mycobiome of Pinus densiflora roots, focusing on how sequencing platforms and database choice influence taxonomic resolution and diversity patterns. Both platforms detected mycorrhizal taxa with similar taxonomic resolution, recovering nearly all taxa previously reported from pine roots. Most mycorrhizal taxa were shared between datasets, although several taxa were detected exclusively by one platform. In terms of diversity, the short-read dataset showed higher diversity due to greater sequencing depth, whereas the long-read dataset offered improved identification of rare or closely related taxa owing to longer sequence information. Moreover, supplementing reference databases with locally derived sequences enhanced taxonomic resolution and the detection of native taxa in both approaches, with a stronger effect for the long-read dataset. Overall, our results emphasize that short- and long-read sequencing each have distinct advantages for mycorrhizal community analysis, and that the use of curated local reference databases is essential to maximize taxonomic resolution and improve the detection of regionally unique taxa.

Vitamin D disrupts NS1-TUFM interaction to suppress pathogenic mitophagy in RSV-induced mitochondrial injury of bronchial epithelial cells
Li Peng, Yao Liu, Xiaofang Ding, Tuhong Yang, Lili Zhong, Fangcai Li
J. Microbiol. 2026;64(1):e2508009.   Published online January 31, 2026
DOI: https://doi.org/10.71150/jm.2508009
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AbstractAbstract PDFSupplementary Material

This study aims to examine the mechanism by which vitamin D mitigates bronchiolitis caused by respiratory syncytial virus (RSV) through the regulation of RSV nonstructural protein 1 (NS1)-TUFM-mediated mitophagy in bronchial epithelial cells. Clinical serum and PBMC samples from RSV-infected children and healthy controls were analyzed for vitamin D, mitochondrial DNA, mitophagy markers (LC3, ATG5, VDAC1, TOMM20, and COXIV), TUFM, and inflammatory cytokines (IL-6, IL-8, and TNF-α). In vitro, human bronchial epithelial cells Beas-2B were transfected with RSV-NS1 plasmid and TUFM silencing or overexpression constructs. Vitamin D (0.1–10 μM) was administered to evaluate mitophagy inhibition using Western blot, immunofluorescence, and JC-1 staining. NS1-TUFM interaction was confirmed by co-immunoprecipitation. RSV-positive patients exhibited reduced serum vitamin D, elevated TUFM and mitophagy markers, impaired mitochondrial mass, and increased inflammation. Vitamin D inversely correlated with LC3 and TUFM. RSV-NS1 overexpression induced mitochondrial translocation of NS1, TUFM-dependent mitophagy activation, and mitochondrial dysfunction (JC-1 depolarization). Vitamin D (10 μM) suppressed mitophagy by redistributing NS1 to the cytosol and reducing mitochondrial TUFM. TUFM overexpression abolished the protective effects of vitamin D on mitophagy and inflammation. In conclusion, vitamin D inhibits mitophagy in bronchial epithelial cells infected with RSV by disrupting NS1-TUFM interaction, suggesting that the vitamin D-TUFM axis may serve as a potential therapeutic target.

Review
Obesity, skin disorders, and the microbiota: Unraveling a complex web
Yu Ri Woo, Hei Sung Kim
J. Microbiol. 2026;64(1):e2508007.   Published online January 31, 2026
DOI: https://doi.org/10.71150/jm.2508007
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AbstractAbstract PDF

Obesity is increasingly recognized as a systemic pro-inflammatory condition that influences not only metabolic and cardiovascular health but also the development and exacerbation of cutaneous inflammatory diseases. This review examines the interplay between obesity, microbial dysbiosis, and two archetypal inflammatory skin disorders—hidradenitis suppurativa (HS) and psoriasis. We highlight how obesity-induced changes in immune signaling, gut permeability, and microbiota composition—both in the gut and the skin—contribute to cutaneous inflammation. Special emphasis is placed on shared pathways such as the Th17/IL-23 and IL-22 signaling axes, adipokine imbalance, and microbial metabolites like short-chain fatty acids and lipopolysaccharides. The review critically evaluates the current literature, distinguishing preclinical insights from clinical evidence, and underscores the potential of microbiota-targeted therapies and metabolic interventions as adjunctive treatment strategies. By integrating metabolic, immunologic, and microbiome data, we synthesize emerging evidence to better understand the gut–skin–obesity interplay and guide future therapeutic innovations.

Full articles
The impact of acid mine drainage on nitrogen-fixing microorganisms in rice root zone soil
Shengni Tian, Penghui Zhang, Qin Zhang, Yupeng Chen, Caijuan Sun, Dan Huang, Wenye Zhang, Mingzhu Zhang
J. Microbiol. 2026;64(1):e2505004.   Published online January 31, 2026
DOI: https://doi.org/10.71150/jm.2505004
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AbstractAbstract PDFSupplementary Material

Acid mine drainage (AMD) poses a serious threat to rice paddy ecosystems, yet its impact on the composition and dynamics of soil nitrogen-fixing microorganisms remains poorly understood. In this study, a pot experiment was conducted using paddy soil collected from a mining area under three pollution treatments, to analyze changes in the structure of the nitrogen-fixing microbial community across different growth stages and treatments. The results showed that AMD irrigation led to soil acidification, sulfate accumulation, and a significant reduction in the diversity of nitrogen-fixing microorganisms in the root zone. Compared to the control, the Shannon index decreased by 11.65–24.79% in contaminated soil. LEfSe analysis indicated that AMD enriched metal-tolerant and sulfate-resistant microbial taxa. Irrigation with clean water was insufficient to fully restore the soil environment. The assembly process of the AMD soil community was governed solely by stochastic processes, indicating structural instability of the community. This study suggests that remediation strategies should prioritize neutralizing acidity and restoring nutrient balance to support the stability and recovery of nitrogen-fixing microorganisms. These findings provide new insight into how AMD disrupts diazotrophic community assembly, with direct implications for paddy soil restoration.

Robiginitalea rubriflava sp. nov. and Robiginitalea insularis sp. nov., isolated from coastal seawaters of the Yellow Sea
Seungyeop Oh, Yeonjung Lim, Meora Rajeev, Jang-Cheon Cho
Received December 12, 2025  Accepted January 7, 2026  Published online January 28, 2026  
DOI: https://doi.org/10.71150/jm.2512009    [Epub ahead of print]
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AbstractAbstract PDFSupplementary Material

Two Gram-stain-negative, aerobic, non-motile, rod-shaped bacterial strains, designated IMCC43444T and IMCC44478T, were isolated from surface seawater collected off Deokjeok Island and Jangbong Island, respectively, in the Yellow Sea. The two strains shared 100% 16S rRNA gene sequence similarity with each other but exhibited ≤ 96.2% similarity to validly published species of the genus Robiginitalea. Complete whole-genome sequences of IMCC43444T and IMCC44478T were 3.21 Mb and 3.30 Mb in size, with DNA G + C contents of 46.5% and 46.4%, respectively. Genome-based relatedness analyses revealed average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values of 90.7% and 42.9% between the two strains, which are well below the accepted species-level thresholds. Furthermore, ANI (≤ 70.2%) and dDDH (≤ 17.8%) values relative to type strains of Robiginitalea species supported the conclusion that strains IMCC43444T and IMCC44478T each represent novel species within the genus. Chemotaxonomic characterization showed that iso-C15:0, iso-C17:0 3-OH and iso-C15:1 G were the major fatty acids of both strains; menaquinone-6 (MK-6) was the sole isoprenoid quinone; and the major polar lipids comprised phosphatidylethanolamine, glycolipids, aminolipids, phospholipids, and other unidentified lipids. Based on phylogenetic, genomic, and phenotypic evidence, strains IMCC43444T and IMCC44478T are proposed as two novel species, Robiginitalea rubriflava sp. nov. and Robiginitalea insularis sp. nov., respectively. The type strains are IMCC43444T (= KCTC 102397T = JCM 37893T) and IMCC44478T (= KCTC 102398T = JCM 37894T).

Cinchonidine induces muscle weakness by inhibiting insulin-mediated IRS-1-AKT signaling pathway
Mi Ran Byun, Sang Hoon Joo, Young-Suk Jung, Joon-Seok Choi
J. Microbiol. 2025;63(12):e2511017.   Published online December 31, 2025
DOI: https://doi.org/10.71150/jm.2511017
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AbstractAbstract PDF

Sarcopenia is an age-related condition marked by a reduction in muscle mass and strength, and it is associated with impaired muscle regeneration and differentiation. While diseases like cardiovascular and chronic liver disease can induce sarcopenia, there is limited evidence regarding the specific diseases and mechanisms responsible for its development. In skeletal muscle, the loss of muscle mass is accompanied by a decrease in myofilament proteins and the inhibition of muscle differentiation in satellite cells. Bioactive compounds obtained from natural products have been traditionally used as therapeutics for diverse conditions. In this report, we investigated the effect of cinchonidine (CD) extracted from Cinchona tree on muscle differentiation of mouse satellite cells, and myoblast cell lines. CD significantly inhibited muscle differentiation by suppressing myotube formation and gene expression of myogenesis markers. In addition, CD reduced muscle differentiation by blocking phosphorylation of insulin receptor substrate 1 (IRS-1) during insulin-induced signal transduction. Therefore, the results show that CD, an antimalarial agent, inhibited muscle differentiation through the suppression of IRS-1 phosphorylation, suggesting that sarcopenia can be induced by CD.

Comparative genome analysis of enterohemorrhagic Escherichia coli ATCC 43894 and its pO157-cured strain 277
Se Kye Kim, Yong-Joon Cho, Carolyn J. Hovde, Sunwoo Hwang, Jonghyun Kim, Jang Won Yoon
J. Microbiol. 2025;63(12):e2511015.   Published online December 31, 2025
DOI: https://doi.org/10.71150/jm.2511015
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AbstractAbstract PDFSupplementary Material

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 ATCC 43894 (also known as EDL932) has been widely used as a reference strain for studying the pathophysiology of EHEC. To elucidate the role of a large virulence plasmid pO157 and its relationship with acid resistance, for example, both EHEC ATCC 43894 and its pO157-cured derivative strain 277 were well studied. However, it is unclear whether or not these two strains are isogenic and share the same genetic background. To address this question, we analyzed the whole genome sequences of ATCC 43894 and 277. As expected, three and two closed contigs were identified from ATCC 43894 and 277, respectively; two contigs shared in both strains were a chromosome and a small un-identified plasmid, and one contig found only in ATCC 43894 was pO157. Surprisingly, our pan-genome analyses of the two sequences revealed several genetic variations including frameshift, substitution, and deletion mutations. In particular, the deletion mutation of hdeD and gadE in ATCC 43894 was identified, and further PCR analysis also confirmed their deletion of a 2.5-kb fragment harboring hdeD, gadE, and mdtE in ATCC 43894. Taken together, our findings demonstrate that EHEC ATCC 43894 harbors genetic mutations affecting glutamate-dependent acid resistance system and imply that the pO157-cured EHEC 277 may not be isogenic to ATCC 43894. This is the first report that such genetic differences between both reference strains of EHEC should be considered in future studies on pathogenic E. coli.

Synergistic anti-obesity effects of Bifidobacterium breve BR3 and Lactiplantibacillus plantarum LP3 via coordinated regulation of lipid metabolism and gut microbiota
Misun Yun, Dooheon Son, Namhee Kim, Se Hee Lee, Eunbee Cho, Sanghyun Lim
J. Microbiol. 2025;63(12):e2511001.   Published online December 31, 2025
DOI: https://doi.org/10.71150/jm.2511001
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AbstractAbstract PDFSupplementary Material

The global rise in obesity and its associated metabolic complications underscores the urgent need for safe and effective interventions. This study investigated the anti-obesity efficacy of a probiotic mixture containing Bifidobacterium breve BR3 and Lactiplantibacillus plantarum LP3 in C57BL/6 mice with high-fat diet (HFD)-induced obesity. After obesity was established by feeding a 60% kcal HFD, the probiotic mixture was administered orally for 4 weeks. Compared with the control group, mice receiving the L. plantarum LP3 and B. breve BR3 mixture exhibited significant reductions in body weight and total fat mass, as assessed by Dual-energy X-ray Absorptiometry (DXA) and Echo Magnetic Resonance Imaging (EchoMRI). The probiotic treatment also lowered serum Aspartate Aminotransferase (AST), Alanine Aminotransferase (ALT), and glucose levels, and attenuated lipid accumulation in both hepatic and epididymal adipose tissues. Transcriptomic profiling revealed upregulation of lipolytic genes (Sirt1, Pparα) and downregulation of lipogenic genes (Srebp1c, Fas), suggesting that the probiotic mixture promotes lipid catabolism while suppressing lipid synthesis. Additionally, serum adipokine levels were favorably modulated, indicating improved metabolic homeostasis. Gut microbiota analysis demonstrated an increased relative abundance of beneficial genera, including Akkermansia and Bacteroides, highlighting a microbiome-mediated contribution to the observed metabolic benefits. Overall, our findings indicate that the combined administration of Lactiplantibacillus plantarum LP3 and Bifidobacterium breve BR3 exerts multi-faceted anti-obesity effects by enhancing lipolysis, regulating lipid metabolism, and restoring a healthy gut microbial balance. This probiotic mixture represents a promising therapeutic approach for managing obesity and related metabolic disorders.

Review
Integrative perspectives on glycosylation networks in fungi and oomycetes
Heeji Moon, Hokyoung Son
J. Microbiol. 2025;63(12):e2510003.   Published online December 31, 2025
DOI: https://doi.org/10.71150/jm.2510003
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AbstractAbstract PDF

Pathogenic fungi pose major threats to both global food security and human health, yet the molecular basis of their virulence remains only partially understood. Beyond genetic and transcriptional control, emerging evidence highlights protein glycosylation as a key post-translational modification that governs fungal development, stress adaptation, and host interactions. Glycosylation regulates protein folding, stability, trafficking, and immune evasion, thereby shaping infection processes across diverse pathogens. While extensively studied in model organisms, our understanding of glycosylation in pathogenic fungi remains fragmented and lacks a coherent framework linking glycosylation dynamics to fungal development and pathogenicity. This review synthesizes recent advances from proteomic, transcriptomic, and glycomic studies in pathogenic fungi, focusing on interspecific variation in glycogenes and enzymes, hierarchical regulatory networks, and glycoprotein-mediated mechanisms of virulence. Finally, we outline current challenges and highlight glycosylation-targeted strategies as promising avenues for antifungal intervention.

Full articles
Proteolytic enzymes from Bacillus subtilis AB2 as antibiofilm adjuvants: Bioprocess optimization, mechanistic insights, and synergy with antibiotics
Afra M. Baghdadi
J. Microbiol. 2025;63(12):e2509019.   Published online December 31, 2025
DOI: https://doi.org/10.71150/jm.2509019
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AbstractAbstract PDFSupplementary Material

Collagenase and keratinase are two important proteolytic enzymes with recognized applications in biotechnology and medicine, particularly in the enzymatic removal of necrotic tissue and the control of infection. In the present work, a soil isolate of Bacillus subtilis strain AB2 (PX453297.1) was optimized for enzyme production under different nutritional and physicochemical conditions. The enzymes were recovered by ammonium sulphate precipitation and dialysis, examined by SDS-PAGE and zymography, and further assessed for pH and temperature optima, stability, the influence of metal ions, and kinetic parameters. Maximum collagenase activity (4.41 ± 0.22 U/ml) was observed at 37°C and pH 7.5 in a glucose–peptone medium, whereas keratinase production was enhanced between 37 and 40°C at pH 7.5 in lactose–peptone medium. Protein bands of approximately 55 and 33 kDa were detected, representing 6.2- and 5.5-fold purification. Collagenase showed an alkaline optimum (pH 10.0, 37–45°C) with Km 0.31% and Vmax 1.92 U/ml, while keratinase exhibited dual optima (pH 3.0 and ~7.0) with Km 0.27% and Vmax 0.84 U/ml. Biofilm assays revealed that collagenase reduced pre-formed biomass by 62–68% and viable counts by 1.1–1.7 log10, clearly outperforming keratinase (41–57%, 0.7–1.2 log10). When combined with conventional antibiotics, both enzymes potentiated activity, with notable synergy between collagenase and oxacillin against Staphylococcus aureus (FICI 0.31–0.37), ciprofloxacin against Pseudomonas aeruginosa (FICI 0.37–0.50), and meropenem against Klebsiella pneumoniae (FICI 0.28–0.44). These results indicate that B. subtilis AB2 produces collagenase and keratinase with distinct biochemical characteristics and strong antibiofilm properties, underscoring their promise as adjuncts in chronic wound care as well as in industrial applications.

Mucilaginibacter florum sp. nov., isolated from the flower of Coreopsis grandiflora and Mucilaginibacter oryzagri sp. nov., isolated from rice paddy soil in Korea
Parthiban Subramanian, Jun Heo, Daseul Lee, Seunghwan Kim, Hyorim Choi, Yunhee Choi, Yiseul Kim
J. Microbiol. 2025;63(12):e2509014.   Published online December 31, 2025
DOI: https://doi.org/10.71150/jm.2509014
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AbstractAbstract PDFSupplementary Material

Two aerobic, Gram-stain-negative, non-motile and rod-shaped bacterial strains designated GGG-R5T and M4-18T were isolated from flowers of golden wave (Coreopsis grandiflora) and rice paddy soil, respectively in the Republic of Korea. Both strains were pigmented and produced flexirubin-type pigments. Based on phylogenetic analysis using 16S rRNA gene sequence, both strains were placed within the genus Mucilaginibacter with M. agri R11T and M. jinjuensis YC7004T both being the closest relatives to GGG-R5T (97.7%) and in case of M4-18T, M. ginsenosidivorax KHI28T (98.5%) was the nearest neighbor. Characteristic to genus Mucilaginibacter, the major cellular fatty acids in both strains were iso-C15:0, iso-C17:0 3-OH, summed feature 3 (C16:1 ω7c and/or C16:1 ω6c); menaquinone-7 was the major menaquinone and phosphatidylethanolamine was the major polar lipid observed. Comparison of genome sequences with the other members of Mucilaginibacter indicated orthologous average nucleotide identity (orthoANI) at 73.3–73.5% for GGG-R5T and 78.9–88.5% for M4-18T. Digital DNA-DNA hybridization (dDDH) values ranged at 19.1–19.7% between GGG-R5T and its neighbor species. In case of M4-18T, the observed range was at 21.9–36.6%. Considering the 16S rRNA similarity, orthoANI and dDDH values as well as comparison of phenotypic and chemotaxonomic characteristics indicated that both strains belonged to genus Mucilaginibacter but were distinctly distinguishable from previously described species. The strains GGG-R5T and M4-18T, therefore represent distinct novel species for which names Mucilaginibacter florum GGG-R5T and Mucilaginibacter oryzagri M4-18T are proposed. The type strains are GGG-R5T (= KACC 22063T = JCM 36590T) and M4-18T (= KACC 22773T = JCM 35894T).

Multi-omic profiling reveals the impact of keratinase kerZJ on mouse gut homeostasis
Xueqing Gan, Yijiao Wen, Si Chen, Famin Ke, Siyuan Liu, Zening Wang, Chunhua Zhang, Xuanting Wang, Qin Wang, Xiaowei Gao
J. Microbiol. 2025;63(12):e2509011.   Published online December 31, 2025
DOI: https://doi.org/10.71150/jm.2509011
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AbstractAbstract PDF

Keratinase kerZJ is a multifunctional protease with potential as a feed additive and functional ingredient. Here we performed an integrated multi‑omics evaluation of its biosafety and impact on gut homeostasis in mice. Our findings confirm that kerZJ is well-tolerated, with no evidence of systemic toxicity or intestinal epithelial damage. Integrated transcriptomic and proteomic analyses revealed that kerZJ reinforces intestinal barrier integrity by upregulating extracellular matrix components, including collagen IV, and modulates mucosal immunity by enhancing B-cell activation and antimicrobial peptide defenses without inducing inflammation. Furthermore, kerZJ administration led to a significant upregulation of digestive enzymes and a dose-dependent increase in short-chain fatty acids production. Microbiome analysis showed that while high-dose kerZJ altered community composition, it enriched for beneficial taxa like Lactobacillaceae and did not induce dysbiosis. These results demonstrate that kerZJ safely enhances gut barrier function, promotes a favorable immune and metabolic environment, and fosters a resilient gut ecosystem, supporting its development as a safe feed additive and nutraceutical component.

Review
Metabolite-mediated mechanisms linking the urinary microbiome to bladder cancer
Thu Anh Trần, Ho Young Lee, Hae Woong Choi
J. Microbiol. 2025;63(11):e2509001.   Published online November 30, 2025
DOI: https://doi.org/10.71150/jm.2509001
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AbstractAbstract PDF

Bladder cancer is the most common malignancy of the urinary tract and is a major health burden globally. Recent advances in microbiome research have revealed that the urinary tract harbors a resident microbial community, overturning the long-held belief in its sterility. Increasing evidence suggests that microbial dysbiosis and microbially derived metabolites contribute to bladder cancer carcinogenesis, progression, and therapeutic responses. Distinct microbial signatures have been observed in bladder cancer patients, with notable differences across disease stages and between primary and recurrent cases. Mechanistic studies have demonstrated that microbe-associated metabolites and toxins can drive DNA damage, chronic inflammation, extracellular matrix remodeling, and epithelial–mesenchymal transition. In addition, biofilm formation allows bacteria to evade immune responses and promotes persistent inflammation, creating a tumor-permissive niche. Beyond pathogenesis, microbial activity also influences therapeutic outcomes; for instance, some microbial pathways can inactivate frontline chemotherapy, while others generate metabolites with anti-tumor properties. Collectively, these patterns define a microbiota–metabolite–immunity axis, presenting opportunities for precision oncology. Targeting microbial pathways, profiling urinary microbiota, and harnessing beneficial metabolites offer promising advancements in biomarker discovery, prognostic refinement, and the development of novel therapeutic strategies for bladder cancer.

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  • The infection–microbiome–immunity axis in bladder cancer: mechanistic insights and therapeutic perspectives
    Shen Pan, Wanlin Cui, Jiaman Lin, Zhujun Wang, Zhenhua Li, Bitian Liu
    Frontiers in Immunology.2026;[Epub]     CrossRef
Full articles
Lactiplantibacillus koreensis sp. nov. and Lactiplantibacillus kimchii sp. nov., isolated from kimchi, a traditional Korean fermented food
Min Ji Lee, Jisu Lee, Sohee Nam, Mi-Ja Jung, Yeon Bee Kim, Yujin Kim, Jeong Ui Yun, Seong Woon Roh, Tae Woong Whon, Che Ok Jeon, Se Hee Lee
J. Microbiol. 2025;63(11):e2507007.   Published online November 30, 2025
DOI: https://doi.org/10.71150/jm.2507007
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AbstractAbstract PDFSupplementary Material

Two Gram-stain-positive, facultatively anaerobic, rod-shaped, and non-motile lactic acid bacterial strains, designated as strains CBA3605T and CBA3606T, were isolated from kimchi, a traditional Korean fermented food. Both strains were oxidase- and catalase-negative, non-spore-forming, non-hemolytic, and non-gas-producing. Optimal growth conditions for the two strains were observed at 30°C, pH 5.0, and 0% NaCl. The two genomes were composed of a circular chromosome and three plasmids and the DNA G + C content of 43.0%, respectively. Strains CBA3605T and CBA3606T were most closely related to Lactiplantibacillus (Lp.) pingfangensis 382-1T with 16S rRNA sequence similarity of 99.4% and 99.1%, respectively. However, the orthologous average nucleotide identities between CBA3605T and CBA3606T were 91.7%, and those with strain 382-1T were 76.9% and 76.5%, respectively. Digital DNA–DNA hybridization values between CBA3605T and CBA3606T were 45.0%, and those with strain 382-1T were 21.4% and 21.0%, respectively. The major fatty acids detected in both strains included C16:0, C18:1 ω9c, and summed features 7 (C19:1 ω7c, C19:1 ω6c, C19:0 cyclo ω10c, and/or C19:0 ω6c). The peptidoglycan of both strains CBA3605T and CBA3606T contained meso-diaminopimelic acid and was classified as A4α type (L-Lys–D-Asp). In polar lipid analyses, only strain CBA3605T contained aminophosphoglycolipid, which was absent in CBA3606T, although both strains harbored same major polar lipids (diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine). Based on phenotypic, phylogenetic, genomic, biochemical, and chemotaxonomic analyses, strains CBA3605T and CBA3606T represent two novel species of the genus Lactiplantibacillus, for which the names Lactiplantibacillus koreensis sp. nov. and Lactiplantibacillus kimchii sp. nov. are proposed, with CBA3605T (= KACC 81073BPT = JCM 37965T), and CBA3606T (= KACC 81074BPT = JCM 37966T) as the type strains.

Inhibition of cardiolipin biosynthesis partially suppresses the sensitivity of an Escherichia coli mutant lacking OmpC to envelope stress
Dae-Beom Ryu, Umji Choi, Gyubin Han, Chang-Ro Lee
J. Microbiol. 2025;63(11):e2507004.   Published online November 30, 2025
DOI: https://doi.org/10.71150/jm.2507004
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AbstractAbstract PDFSupplementary Material

Porins in the outer membrane (OM) of Gram-negative bacteria play two main functions: passage of various extracellular molecules and maintenance of membrane integrity. OmpC, a non-specific porin, is involved in both functions; however, the exact mechanism of maintenance of membrane integrity remains unknown. In this study, we found that inhibiting cardiolipin biosynthesis partially restored the growth defect of the ompC mutant under envelope stress. Among the three enzymes involved in cardiolipin biosynthesis, ClsABC, this effect is primarily associated with ClsA. Notably, the deletion of ClsA also suppressed the similar phenotypes of an Escherichia coli mutant lacking YhdP, a transmembrane protein involved in phospholipid transport from the inner membrane to the OM. Collectively, these results imply that OmpC may contribute to membrane integrity, partially through mechanisms linked to transport or biosynthesis of phospholipids such as cardiolipin.

Development of an RT-LAMP−CRISPR/Cas12a assay for rapid and specific detection of Bandavirus dabieense
Bo Seung Song, Yun Hee Baek, Eun-Ha Kim, Hyeok-Il Kwon, Ah-Hyeon Kim, Si-Hyun Lee, Yu-Bin Son, Soo-Hyeon Kim, Min-Suk Song, Young Ki Choi, Su-Jin Park
J. Microbiol. 2025;63(11):e2506013.   Published online November 30, 2025
DOI: https://doi.org/10.71150/jm.2506013
  • 1,436 View
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AbstractAbstract PDF

Bandavirus dabieense, a single-stranded RNA virus, is the causative agent of severe fever with thrombocytopenia syndrome (SFTS), a disease associated with high fatality rates. Early and accurate diagnosis is essential for improving clinical outcomes, particularly given the limited therapeutic options and high mortality rates associated with SFTS. However, while highly sensitive, conventional diagnostic methods such as PCR and qRT-PCR require specialized laboratory facilities and trained personnel, making them impractical for rapid detection in resource-limited settings. To address these challenges, we developed a rapid and highly sensitive assay for Bandavirus dabieense detection by integrating reverse transcription loop-mediated isothermal amplification (RT-LAMP) with CRISPR/Cas12a technology. LAMP primers and guide RNA sequences were designed to target the L gene, ensuring broad detection across viral genotypes. The optimized assay demonstrated a detection limit of 5 RNA copies per reaction, showing more sensitivity than qRT-PCR, and exhibited 100% concordance with qRT-PCR results in clinical samples. Given its speed, accuracy, and field applicability, this LAMP-CRISPR/Cas12a-based assay represents a promising diagnostic tool for early SFTSV detection, particularly in resource-constrained environments where conventional molecular diagnostics are not readily available.

Encapsulin protein MAV2054 enhances Mycobacterium avium virulence by promoting Cdc42-dependent epithelial cell invasion
Dong Ho Kim, I Jeong Jo, Min Ju Kang, Yi Seol Kim, Duyen Do Tran Huong, Kyungho Woo, Ho-Sung Park, Hwa-Jung Kim, Chul Hee Choi
J. Microbiol. 2025;63(11):e2506008.   Published online November 30, 2025
DOI: https://doi.org/10.71150/jm.2506008
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AbstractAbstract PDF

Mycobacterium avium complex (MAC) organisms are widespread environmental pathogens associated with chronic pulmonary infections. Although M. avium is known to invade epithelial cells, the molecular mechanisms underlying this process remain incompletely understood. In this study, we identified a novel role for MAVRS09815 (formerly MAV2054), a family 2A encapsulin nanocompartment shell protein, in mediating bacterial adhesion, epithelial cell invasion, and in vivo virulence. We engineered a recombinant M. smegmatis strain expressing MAV2054 (Ms_2054) and an M. avium MAV2054 deletion mutant (Δ2054). Ms_2054 exhibited enhanced epithelial invasion, whereas Δ2054 showed reduced intracellular survival. Recombinant MAV2054 protein was bound directly to human epithelial cells in a dose-dependent manner. Pretreatment of host cells with cytochalasin D or vinblastine significantly inhibited bacterial internalization, indicating that MAV2054-mediated invasion is cytoskeleton-dependent. Confocal and scanning electron microscopy revealed MAV2054-dependent membrane rearrangements during infection. Pull-down assays demonstrated that MAV2054 activates Cdc42, a key regulator of actin polymerization, with reduced activation observed in Δ2054-infected cells. In a murine intratracheal infection model, the Δ2054 exhibited significantly reduced bacterial burdens and lung inflammation compared to the wild type. These findings demonstrate that MAV2054 enhances M. avium virulence by promoting epithelial cell invasion through Cdc42-dependent cytoskeletal remodeling. This study reveals a previously unrecognized role for an encapsulin-like protein in host-pathogen interactions and highlights its potential as a therapeutic target in MAC infections.

Safety evaluation and hypolipidemic ability of water-soluble blue pigment extracted by HPD-400 resin from Quambalaria cyanescens
Ruobing Shi, Chengzhong Wang, Nianping Xue, Zhiguo Zhang
J. Microbiol. 2025;63(11):e2412011.   Published online November 30, 2025
DOI: https://doi.org/10.71150/jm.2412011
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AbstractAbstract PDF

The oral administration of synthetic drugs can effectively reduce blood lipid levels, but adverse reactions may occur. Because of this, the hypolipidemic ability of natural products has been increasingly investigated. We evaluate the safety and hypolipidemic characteristics of a water-soluble blue pigment extracted using HPD-400 resin from the fungus Quambalaria cyanescens. Hypolipidemic ability was examined by constructing a hyperlipidemia model with different doses of blue pigment (50, 100, and 200 mg/kg. mouse body weight) for 28 d. Blue pigment purity increased from 20.32% to 70.70% following treatment with HPD-400 resin. Acute toxicity tests revealed blue pigment sourced from Q. cyanescens to have no toxic effects on mouse body weight, mortality, or behavioral characteristics. Subacute toxicity tests revealed no significant differences in food intake, body weight, or organ weights between treatment groups and controls. Histopathological examination of the liver and kidney tissues of mice administered blue pigment were normal, and serum enzyme activities and blood constituents were also within normal ranges. Blue pigment can significantly reduce the weight of mice, reduce liver and kidney damage and fat accumulation. It can also reduce total cholesterol, triglyceride and low density lipoprotein cholesterol in serum and liver tissue, and increase the level of high density lipoprotein cholesterol. Reduce the levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, creatinine, urea and uric acid in serum. Increase the activities of total superoxide dismutase, glutathione peroxidase and catalase in serum and liver tissue, reduce the content of malondialdehyde, and up-regulate liver lipase and lipoprotein lipase. Our work proves that blue pigment is nontoxic, has the function of reducing blood lipid, and can alleviate obesity-related symptoms by regulating lipid metabolism and oxidative stress.

Lactobacillus crispatus KBL693 alleviates atopic dermatitis symptoms through immune modulation
Seokcheon Song, Jun-Hyeong Kim, Sung Jae Jang, Eun Jung Jo, Sang Kyun Lim, GwangPyo Ko
J. Microbiol. 2025;63(10):e2509005.   Published online October 31, 2025
DOI: https://doi.org/10.71150/jm.2509005
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AbstractAbstract PDFSupplementary Material

Atopic dermatitis (AD) is a widespread inflammatory skin condition that affects the population worldwide. Given the implication of microbiota in AD pathogenesis, we investigated whether human-derived Lactobacillus strains could modulate AD. In this study, we identified Lactobacillus crispatus KBL693 as a probiotic candidate for AD treatment. In vitro, KBL693 suppressed mast cell degranulation and IL-4 production by T cells, suggesting its ability to attenuate key type 2 immune responses. Consistent outcomes were observed in a murine AD model, where oral administration of KBL693 alleviated disease symptoms and reduced hallmark type 2 immune markers, including plasma IgE as well as IL-4, IL-5, and IL-13 levels in skin lesions. In addition to downregulating these AD-associated immune responses, KBL693 promoted regulatory T cell (Treg) expansion in mesenteric lymph nodes, indicating its potential to restore immune balance. Collectively, these findings highlight the therapeutic potential of KBL693 for AD through enhancement of Tregs and suppression of type 2 immune responses.

Review
Structural analysis of dual specificity phosphatases, the only type of protein tyrosine phosphatases found in humans and across diverse microorganisms
Bonsu Ku
J. Microbiol. 2025;63(10):e2506006.   Published online October 31, 2025
DOI: https://doi.org/10.71150/jm.2506006
  • 1,683 View
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AbstractAbstract PDFSupplementary Material

Dual specificity phosphatases (DUSPs), a subfamily of the protein tyrosine phosphatase (PTP) family, dephosphorylate not only phosphotyrosine but also phosphoserine and phosphothreonine residues. Beyond the 26 members of this family in humans, DUSPs represent the only type of PTPs found across a wide range of microorganisms, including bacteria, archaea, and viruses. This review presents a comprehensive structural analysis of human and microbial DUSPs. These proteins commonly share core features, such as a typical DUSP fold, shallow active site pocket, signature active site motif known as the P-loop, and conserved aspartate residue that acts as a general acid/base. However, DUSPs from diverse microorganisms also display unique structural and functional characteristics. Pseudomonas aeruginosa TpbA is the only bacterial DUSP identified to date, while a second candidate was proposed in this review. Archaeal DUSPs are hyperthermostable, contain a unique motif in their P-loops, and employ dual general acid/base residues. Poxviral DUSPs are characterized by the formation of domain-swapped homodimers. The presence of DUSPs across all domains of life and viruses, along with their low specificity for phosphorylated amino acids and structural similarity to classical PTPs, suggests that DUSPs represent the ancestral form of PTPs.

Full articles
Mannose phosphotransferase system subunit IID of Streptococcus mutans elicits maturation and activation of dendritic cells
Sungho Jeong, Chaeyeon Park, Dongwook Lee, Hyun Jung Ji, Ho Seong Seo, Cheol-Heui Yun, Jintaek Im, Seung Hyun Han
J. Microbiol. 2025;63(10):e2505014.   Published online October 31, 2025
DOI: https://doi.org/10.71150/jm.2505014
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AbstractAbstract PDF

Streptococcus mutans is a Gram-positive pathogen that causes dental caries and subsequent pulpal infection leading to pulpitis. Although dendritic cells (DCs) are known to be involved in disease progression and immune responses during S. mutans infection, little is known about which component of S. mutans is responsible for the DC responses. Although the mannose phosphotransferase system (Man-PTS) is the primary sugar transporter of S. mutans, it is also a potential virulence factor. Since Man-PTS subunit IID (ManIID) embedded on the bacterial membrane is indispensable for Man-PTS function, we investigated its role in the maturation and activation of DCs stimulated with a ManIID-deficient strain (Δpts) of S. mutans and recombinant ManIID (rManIID) protein. When mouse bone marrow-derived DCs were treated with heat-killed S. mutans wild-type (WT) or Δpts, bacterial adherence and internalization of Δpts were lower than those of WT. Moreover, the heat-killed S. mutans Δpts strain was inferior to the wild-type in inducing expression of phenotypic maturation markers, such as CD80, CD86, MHC-I, and MHC-II, and proinflammatory cytokine, IL-6. In line with the trends in marker expression, the endocytic capacity of DCs treated with the Δpts strain was comparable to that of untreated DCs whereas DCs treated with the WT strain dose-dependently lost their endocytic capacity. Furthermore, rManIID dose-dependently promoted both phenotypic maturation marker expression and IL-6 production by DCs. Collectively, these results demonstrate that ManIID plays a crucial role in the adhesion and internalization of S. mutans into DCs and is one of the major immune-stimulating agents responsible for maturation and activation of DCs during S. mutans infection.

Genome-based classification of Paraniabella aurantiaca gen. nov., sp. nov., isolated from soil and taxonomic reclassification of five species within the genus Niabella
Yong-Seok Kim, Yerang Yang, Miryung Kim, Do-Hoon Lee, Chang-Jun Cha
J. Microbiol. 2025;63(10):e2505005.   Published online October 31, 2025
DOI: https://doi.org/10.71150/jm.2505005
  • 2,054 View
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AbstractAbstract PDFSupplementary Material

A Gram-stain-negative, aerobic, non-motile, rod-shaped, and orange-pigmented bacterium, designated CJ426T, was isolated from ginseng soil in Anseong, Korea. Strain CJ426T grew optimally on Reasoner’s 2A agar at 30°C and pH 7.0 in the absence of NaCl. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain CJ426T belonged to the family Chitinophagaceae and had the highest sequence similarity with Niabella hibiscisoli KACC 18857T (98.7%). The 16S rRNA gene sequence similarities with other members of the genus Niabella ranged from 92.3% to 98.1%. Phylogenomic analyses and overall genomic relatedness indices, including average nucleotide identity, average amino acid identity, and the percentage of conserved proteins values, supported the classification of strain CJ426T as a representative of a novel genus within the family Chitinophagaceae. Furthermore, genome-based analyses suggested that five members of the genus Niabella, including N. aquatica, N. defluvii, N. ginsengisoli, N. hibiscisoli, and, N. yanshanensis, should be separated from other Niabella species and be assigned as a novel genus. The major isoprenoid quinone of strain CJ426T was menaquinone-7 (MK-7). The predominant polar lipids were phosphatidylethanolamine and six unidentified aminolipids. The major fatty acids were iso-C15:0, iso-C15:1 G, and iso-C17:0 3-OH. The genome of strain CJ426T was 6.3 Mbp in size, consisting of three contigs, with a G + C content of 41.9%. Based on a polyphasic taxonomic approach, strain CJ426T represents a novel genus and species within the family Chitinophagaceae, for which the name Paraniabella aurantiaca gen. nov., sp. nov. is proposed. The type strain is CJ426T (= KACC 23908T = JCM 37728T).

Cryo-EM structure of the glycosylated protein CgeA in the crust of Bacillus subtilis endospores
Migak Park, Doyeon Kim, Yeongjin Baek, Eunbyul Jo, Jaekyung Hyun, Nam-Chul Ha
J. Microbiol. 2025;63(10):e2504013.   Published online October 31, 2025
DOI: https://doi.org/10.71150/jm.2504013
  • 1,233 View
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AbstractAbstract PDFSupplementary Material

The Bacillus subtilis spore crust is an exceptionally robust proteinaceous layer that protects spores under extreme environmental conditions. Among its key components, CgeA, a glycosylation-associated protein, plays a critical role in modifying crust properties through its glycosylated moiety, enhancing spore dispersal in aqueous environments. In this study, we present the high-resolution cryo-electron microscopy structure of the core region of CgeA at 3.05 Å resolution, revealing a doughnut-like hexameric assembly. The N-terminal regions are disordered, whereas the C-terminal region forms the core of the hexamer. Although the loop containing Thr112 was not resolved in the density map, its location can be inferred from surrounding residues, suggesting that Thr112 is situated on the exposed surface of the hexamer. On the opposite face, a distinct electrostatic pattern is observed, featuring a negatively charged central pore and a positively charged outer surface. Modeling and biochemical studies with the putative glycosyltransferase CgeB provide insights into how the glycosyl group is transferred to Thr112. This study offers a molecular-level understanding of the assembly, glycosylation, and environmental adaptability of the B. subtilis spore crust, with valuable implications for controlling spore formation in industrial applications.

Bak and Bax are crucial for Gbp2-mediated pyroptosis during Vibrio and Salmonella infections
Yongyang Luo, Jeehyeon Bae
J. Microbiol. 2025;63(9):e2508004.   Published online September 30, 2025
DOI: https://doi.org/10.71150/jm.2508004
  • 1,336 View
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AbstractAbstract PDFSupplementary Material

Pyroptosis a lytic form of programmed cell death, is a crucial host defense mechanism against bacterial pathogens. While caspase-mediated pathways are central to pyroptosis, the involvement of apoptotic regulators such as Bak, Bax, and MCL-1 in bacterial infection-induced pyroptosis remains unclear. Here, we investigated how these BCL-2 family proteins modulate pyroptosis induced by Vibrio vulnificus and Salmonella enterica serovar Typhimurium in murine cells. In mouse embryonic fibroblasts (MEFs), both pathogens strongly induced Gbp2 expression and activated caspase‑11, whereas activation of caspase‑1 occurred only in macrophages, indicating engagement of both non-canonical and canonical pyroptosis pathways. Importantly, Bak-/- and Bax-/- MEFs exhibited significantly reduced Gbp2 upregulation and caspase-11 activation-an effect most pronounced in Bak-deficient cells leading to attenuated pyroptotic cell death. These data suggest that pro-apoptotic proteins, Bak and Bax, act as positive regulators that amplify the Gbp2-caspase-11 axis. Conversely, overexpression of the anti-apoptotic protein MCL‑1 had no significant impact on Gbp2 expression, caspase activation, membrane integrity, or LDH release, indicating that pyroptosis proceeds independently of MCL‑1 regulation. Collectively, our findings uncover a novel role for Bak and Bax in promoting Gbp2-driven pyroptosis during Gram-negative bacterial infections, while MCL‑1 does not impede this process. This work expands our understanding of the crosstalk between apoptotic and pyroptotic pathways in innate immune responses.

Protocol
Protocol for efficient recovery of high-quality DNA from microbiome of marine invertebrates
Yeong-Jun Park, Jae Kyu Lim, Yeon-Ju Lee, Kae Kyoung Kwon
J. Microbiol. 2025;63(9):e2507003.   Published online September 30, 2025
DOI: https://doi.org/10.71150/jm.2507003
  • 2,140 View
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AbstractAbstract PDF

Marine organisms often form symbiotic relationships with various microorganisms to adapt and thrive in harsh environments. These symbiotic microbes contribute to host survival by providing nutrition, modulating the hosts’ immune system, and supporting overall physiological stability. Advances in high-throughput sequencing technologies have enabled a deeper understanding of the structure and function of symbiotic microbial communities, as well as host-microbe interactions. Notably, symbiotic bacteria associated with marine invertebrates such as corals and sponges are recognized as a potential source of useful bioactive compounds, including antibiotics and enzymes. However, obtaining high-quality microbial DNA from host tissues still remains a technical challenge due to the presence of unknown substances. This study focuses on optimizing sample preparation and DNA extraction procedures and additional purification to improve the recovery of microbial DNA while minimizing host DNA contamination. Comparison between several methods was conducted using sponge samples to evaluate DNA quality and microbial recovery. A sample designated as 2110BU-001 was collected from the east coast of the Republic of Korea and used for culture-independent microbial cell isolation. Total bacterial DNA was extracted by using a manual Phenol-Chloroform protocol and three commercial kits. DNA extracted using the standard manual method showed both the highest yield and the largest fragment size. However, PCR (Polymerase chain reaction) test showed that quality of manually extracted DNA was not enough for sequencing. Therefore, the quality of DNA was improved through additional purification steps. Briefly, host eukaryotic cells were removed by mechanical process and almost only bacterial DNA was successfully obtained by combination of manual extraction method and further purification processes. The established protocol was successfully introduced to extraction of metagenomic DNA from mussel and jellyfish microbiomes, indicating that it can be widely applied to various marine organisms.

Full articles
PhoU interaction with the PhoR PAS domain is required for repression of the pho regulon and Salmonella virulence, but not for polyphosphate accumulation
Seungwoo Baek, Soomin Choi, Yoontak Han, Eunna Choi, Shinae Park, Jung-Shin Lee, Eun-Jin Lee
J. Microbiol. 2025;63(9):e2505013.   Published online September 30, 2025
DOI: https://doi.org/10.71150/jm.2505013
  • 1,688 View
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AbstractAbstract PDFSupplementary Material

The pho regulon plays a critical role in maintaining phosphate homeostasis in bacteria, with the PhoU protein functioning as a regulator that bridges the PhoB/PhoR two-component system and the PstSCAB2 phosphate transporter. While PhoU is known to suppress PhoR autophosphorylation under high phosphate conditions via interaction with its PAS domain, its broader regulatory functions remain elusive. Here, we investigated the role of the PhoU Ala147 residue in Salmonella enterica serovar Typhimurium using a phoUA147E substitution mutant. Bacterial two-hybrid and immunoprecipitation assays confirmed that Ala147 is essential for PhoU-PhoR PAS domain interaction, and its substitution leads to derepression of pho regulon genes, even in high phosphate conditions. This disruption impaired Salmonella survival inside macrophages and mouse virulence, demonstrating the importance of PhoU-PhoR interaction in Salmonella pathogenesis. However, unlike the phoU deletion mutant, the phoUA147E mutant does not exhibit growth defects or polyphosphate accumulation, indicating that the PhoU-PhoR interaction is not involved in these phenotypes. Our findings reveal PhoU as a multifaceted regulator, coordinating phosphate uptake and pho regulon expression through distinct molecular interactions, and provide new insights into its role in bacterial physiology and virulence.

Exploring the biosynthetic potential of Korean Actinobacteria for antibacterial metabolite discovery
Sehong Park, Hyun-Woo Je, Yujin Cha, Boncheol Gu, Yeojeong Cho, Jin-Il Kim, Ji Won Seo, Seung Bum Kim, Jino Son, Moonsuk Hur, Changmin Sung, Min-Kyu Oh, Hahk-Soo Kang
J. Microbiol. 2025;63(9):e2504002.   Published online September 30, 2025
DOI: https://doi.org/10.71150/jm.2504002
  • 1,356 View
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AbstractAbstract PDFSupplementary Material

Actinobacteria, a phylum of Gram-positive bacteria, are renowned for their remarkable ability to produce antibacterial natural products. The National Institute of Biological Resources (NIBR) of Korea maintains a collection of Korean native actinobacteria. In this study, we explored the phylogenetic and biosynthetic diversity of the NIBR actinobacteria collection to assess its potential as a source of new antibacterial natural products. A 16S rDNA-based phylogenetic analysis revealed a high level of genetic diversity within the collection, with a predominance of Streptomyces, along with rare actinobacterial genera such as Kitasatospora and Micromonospora. Additionally, genetic network analysis of biosynthetic gene clusters (BGCs) from 15 sequenced NIBR actinobacterial strains demonstrated extensive BGC diversity, with many clusters identified as cryptic. Screening of culture extracts for antibacterial activity, followed by dereplication of active extracts, suggested the presence of potentially novel antibacterial natural products. Activity-guided isolation and whole-genome sequencing of the active strain KU57 led to the isolation of one new and three known svetamycin congeners along with their BGC. Overall, our findings highlight the NIBR actinobacteria collection as a valuable source for the discovery of new antibacterial natural products.

Pycnogenol reduces the expression of P. aeruginosa T3SS and inflammatory response in NCI-H292 cells
Seung-Ho Kim, Da Yun Seo, Sang-Bae Han, Un-Hwan Ha, Ji-Won Park, Kyung-Seop Ahn
J. Microbiol. 2025;63(10):2503004.   Published online September 19, 2025
DOI: https://doi.org/10.71150/jm.2503004
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AbstractAbstract PDFSupplementary Material

Nosocomial infections caused by Pseudomonas aeruginosa (P. aeruginosa) have become increasingly common, particularly among immunocompromised individuals, who experience high mortality rates and prolonged treatment durations due to the limited availability of effective therapies. In this study, we screened for anti-ExoS compounds targeting P. aeruginosa and identified pycnogenol (PYC) as a potent inhibitor of the type III secretion system (T3SS), a major virulence mechanism responsible for the translocation of effectors such as ExoS. Using ELISA, western blotting, and real-time PCR analyses in both P. aeruginosa and infected H292 cells, we found that PYC significantly reduced T3SS activity. Mechanistically, PYC suppressed the transcription of T3SS-related genes by downregulating exsA expression in P. aeruginosa. Furthermore, pretreatment with PYC attenuated the cytotoxic effects and reduced the expression of proinflammatory cytokines, including interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-18 (IL-18), in P. aeruginosa-infected H292 cells. These effects were associated with the inhibition of NF-κB signaling and inflammasome activation. Taken together, our findings suggest that PYC may serve as a promising therapeutic candidate against P. aeruginosa infections by targeting T3SS-mediated virulence and modulating host inflammatory responses.

Detection system− and strain−dependent diversity of de novo [PSI+] prion generation and phenotypes in Saccharomyces cerevisiae
Moonil Son
J. Microbiol. 2025;63(10):e2506009.   Published online September 18, 2025
DOI: https://doi.org/10.71150/jm.2506009
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AbstractAbstract PDF

Yeast prion [PSI+], an amyloid form of the translation termination factor Sup35p/eRF3, causes translational stop codon readthrough by sequestering functional Sup35p. This unique phenotype may be analyzed via [PSI+]−suppressible nonsense alleles, and has greatly contributed to the advancement in yeast prion research. For comparing canonical reporters, like chromosomal ade1−14 or ade2−1, and plasmid-borne ura3−14, the de novo generation and characteristics of [PSI+] was investigated across common yeast laboratory strains (BY4741, 74D−694, and 779−6A). The results showed significant variability in [PSI+] induction frequency among strains. [PSI+] was successfully induced in BY4741 and frequently in 74D−694 (via Ade+ selection), but not in 779−6A. Notably, [PSI+] clones, even from identical genetic backgrounds, displayed vastly different nonsense suppression phenotypes depending on the reporter allele used; resulting in diverse growth patterns and suppression levels. Quantitative analyses revealed that prion seed counts fluctuated significantly based on the detection allele and observed phenotype. Furthermore, Sup35p aggregate visualization revealed distinct structural patterns between BY4741 and 74D−694, indicating strain-specific differences. Transferring [PIN+] prion variants from different strains into a common [psi−][pin−] background yielded similar [PSI+] inducibility and seed numbers, suggesting that the observed phenotypic and quantitative diversities of [PSI+] prions stem primarily from the interplay between the specific reporter detection system and the host strain's genetic background rather than solely from inherent differences in the initial [PIN+] prion or fundamental changes in the [PSI+] protein itself. This study underscores the crucial need to consider both the detection methodology and host genetic context for accurate prion variant characterization.

Crystal structures of the μ2 subunit of clathrin-adaptor protein 2 in complex with peptides derived from human papillomavirus 16 E7
Sujin Jung, Dahwan Lim, Joon Sig Choi, Ho-Chul Shin, Seung Jun Kim, Bonsu Ku
J. Microbiol. 2025;63(8):e2505003.   Published online August 31, 2025
DOI: https://doi.org/10.71150/jm.2505003
  • 1,251 View
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AbstractAbstract PDF

Human papillomaviruses (HPVs) cause abnormal cellular proliferation, leading to malignant or benign lesions, such as cervical cancer and warts. The genome of HPV16, the most prevalent high-risk oncogenic genotype within the Alphapapillomavirus genus, encodes two oncoproteins. One of these proteins, E7, interacts with multiple host proteins and modulates their functions through distinct pathways. The CR2 domain of HPV16 E7 was recently reported to interact with the μ2 subunit of clathrin-adaptor protein 2 (AP2-μ2), an adaptor complex involved in cargo internalization during clathrin-mediated endocytosis. In this study, to provide molecular insights into their intermolecular interactions, we determined the crystal structures of AP2-μ2 in complex with the HPV16 E7-derived peptides. Subsequent biochemical analyses revealed that this interaction is primarily maintained by the Y-x-x-Φ motif and further supported by acidic cluster residues of HPV16 E7. Finally, sequence alignment of the E7 CR2 domains from various HPV genotypes showed that the AP2-μ2-binding motif is largely conserved in Alpha-, Beta-, and Mupapillomaviruses, but not in Nu- and Gammapapillomaviruses.

Review
CRISPR-Cas technologies: Emerging tools from research to clinical application
Hana Hyeon, Soonhye Hwang, Yongyang Luo, Eunkyoung Shin, Ji-Hyun Yeom, Hong-Man Kim, Minkyung Ryu, Kangseok Lee
J. Microbiol. 2025;63(8):e2504012.   Published online August 31, 2025
DOI: https://doi.org/10.71150/jm.2504012
  • 11,999 View
  • 172 Download
  • 1 Web of Science
  • 1 Crossref
AbstractAbstract PDF

CRISPR-Cas technologies have emerged as powerful and versatile tools in gene therapy. In addition to the widely used SpCas9 system, alternative platforms including modified amino acid sequences, size-optimized variants, and other Cas enzymes from diverse bacterial species have been developed to apply this technology in various genetic contexts. In addition, base editors and prime editors for precise gene editing, the Cas13 system targeting RNA, and CRISPRa/i systems have enabled diverse and adaptable approaches for genome and RNA editing, as well as for regulating gene expression. Typically, CRISPR-Cas components are transported to the target in the form of DNA, RNA, or ribonucleoprotein complexes using various delivery methods, such as electroporation, adeno-associated viruses, and lipid nanoparticles. To amplify therapeutic efficiency, continued developments in targeted delivery technologies are required, with increased safety and stability of therapeutic biomolecules. CRISPR-based therapeutics hold an inexhaustible potential for the treatment of many diseases, including rare congenital diseases, by making permanent corrections at the genomic DNA level. In this review, we present various CRISPR-based tools, their delivery systems, and clinical progress in the CRISPR-Cas technology, highlighting its innovative prospects for gene therapy.

Citations

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Full articles
Mouse strain-dependent neutralizing antibody responses to Zika virus vaccines
Sang Hwan Seo, Jung-ah Choi, Eunji Yang, Hayan Park, Dae-Im Jung, Jae-Ouk Kim, Jae Seung Yang, Manki Song
J. Microbiol. 2025;63(8):e2504005.   Published online August 31, 2025
DOI: https://doi.org/10.71150/jm.2504005
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  • 2 Crossref
AbstractAbstract PDF

The 2015 Zika virus (ZIKV) outbreak in Brazil and its global spread underscored the urgent need for effective and broadly protective vaccines. While C57BL/6 and BALB/c mice are widely used in preclinical vaccine research, direct comparisons of their ability to elicit ZIKV-specific neutralizing antibodies (nAbs) remain limited. This study aimed to systematically evaluate and compare the immunogenic potential of these two common mouse strains across diverse vaccine platforms, focusing on their capacity to generate functional neutralizing antibody responses. We assessed nAb and IgG responses following four vaccination strategies: (1) DNA vaccine encoding prMEΔTM followed by E protein domain III boost, (2) recombinant EΔTM protein expressed using baculovirus system, (3) formalin-inactivated ZIKV, and (4) live ZIKV. Although both strains generated detectable ZIKV- and E protein-specific IgG, the magnitude and quality of responses varied by vaccine platform and strain. Notably, C57BL/6 mice consistently mounted significantly higher nAb titers than BALB/c mice across all immunization groups, including subunit- and whole-virus-based vaccines. In contrast, BALB/c mice showed lower or undetectable nAb responses, despite comparable or higher total IgG levels in some cases. These findings show that host genetic background is a critical determinant of vaccine-induced neutralization and underscore the importance of selecting appropriate animal models in ZIKV vaccine development. C57BL/6 mice, due to their robust nAb responses, represent a reliable model for evaluating vaccine immunogenicity. Conversely, the limited nAb responses in BALB/c mice position them as a potential low-responder model, offering a stringent system to test the potency and breadth of protective immunity under suboptimal conditions.

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  • The Pathogenesis and Virulence of the Major Enterovirus Pathogens Associated with Severe Clinical Manifestations: A Comprehensive Review
    Yuwei Liu, Maiheliya Maisimu, Zhihang Ge, Suling Xiao, Haoran Wang
    Cells.2025; 14(20): 1617.     CrossRef
  • Development and Immunogenicity Assessment of a Multi-Epitope Antigen Against Zika Virus: An In Silico and In Vivo Approach
    Lígia Rosa Sales Leal, Matheus Gardini Amâncio Marques de Sena, Maria da Conceição Viana Invenção, Ingrid Andrêssa de Moura, André Luiz Santos de Jesus, Georon Ferreira de Sousa, Bárbara Rafaela da Silva Barros, Cristiane Moutinho Lagos de Melo, Lindomar
    Vaccines.2025; 14(1): 31.     CrossRef
Staphylococcus parequorum sp. nov. and Staphylococcus halotolerans sp. nov., isolated from traditional Korean soybean foods
Ju Hye Baek, Dong Min Han, Dae Gyu Choi, Chae Yeong Moon, Jae Kyeong Lee, Chul-Hong Kim, Jung-Woong Kim, Che Ok Jeon
J. Microbiol. 2025;63(8):e2503003.   Published online August 31, 2025
DOI: https://doi.org/10.71150/jm.2503003
Correction in: J. Microbiol 2025;63(9):e2509100 Correction in: J. Microbiol 2025;63(10):e2510101
  • 2,354 View
  • 100 Download
  • 2 Web of Science
AbstractAbstract PDFSupplementary Material

Strains Mo2-6T, S9, KG4-3T, and 50Mo3-2, identified as coagulase-negative, Gram-stain-positive, halotolerant, non-motile coccoid bacteria, were isolated from traditional Korean soybean foods. Strains Mo2-6T and S9 were both catalase- and oxidase-negative, whereas KG4-3T and 50Mo3-2 were catalase-positive but oxidase-negative. The optimal growth conditions for Mo2-6T and S9 were 30°C, 2% NaCl, and pH 7.0, while KG4-3T and 50Mo3-2 grew best at 35°C, 2% NaCl, and pH 7.0. All strains contained menaquinone-7 as the predominant isoprenoid quinone, with anteiso-C15:0 and iso-C15:0 as the major cellular fatty acids (> 10%). Additionally, anteiso-C13:0 was a major fatty acid in strain KG4-3T. The DNA G + C contents of strains Mo2-6T, S9, KG4-3T, and 50Mo3-2 were 33.4%, 33.3%, 32.5%, and 32.7%, respectively. Phylogenetic analyses based on the 16S rRNA gene and whole-genome sequences revealed that strains Mo2-6T and S9, as well as KG4-3T and 50Mo3-2, formed distinct lineages within the genus Staphylococcus. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) analyses confirmed that strains Mo2-6T and S9, as well as KG4-3T and 50Mo3-2, belonged to the same species. Meanwhile, dDDH and ANI values between strains Mo2-6T and KG4-3T, as well as comparisons with other Staphylococcus type strains, were below the species delineation thresholds, indicating they represent novel species. Based on phenotypic, chemotaxonomic, and molecular data, we propose strain Mo2-6T as the type strain of Staphylococcus parequorum sp. nov. (=KACC 23685T =JCM 37038T) and strain KG4-3T as the type strain of Staphylococcus halotolerans sp. nov. (=KACC 23684T =JCM 37037T).

Multi-omics to evaluate the protective mechanisms during Akkermansia muciniphila treatment of Candida albicans colonization and subsequent infection
Qiulin Luo, Huan Zhang, Youming Pu, Yingpu Wei, Jiangkun Yu, Xiaoshen Wang, Qin Cai, Ying Hu, Wenli Yuan
J. Microbiol. 2025;63(8):e2502007.   Published online August 31, 2025
DOI: https://doi.org/10.71150/jm.2502007
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AbstractAbstract PDFSupplementary Material

Akkermansia muciniphila (AKK, A. muciniphila) fortifies the intestinal barrier, inhibits the colonization of pathogenic bacteria, and protects the host’s health. Nevertheless, the existing literature offers inadequate evidence to ascertain whether A. muciniphila can effectively treat Candida albicans (C. albicans) infections in vitro, and the underlying mechanisms remain ambiguous. This study, animal models were established through gavage with clinical isolates of C. albicans to induce gastrointestinal tract colonization and subsequent translocation infection. The models were subsequently administered A. muciniphila. We examined the analysis of 16S rRNA gene sequencing, metabolomics of colonic contents, and transcriptomics of colonic tissue. The intestinal barrier, inflammatory responses, and immune cell infiltration are analyzed. This study revealed that A. muciniphila markedly mitigated C. albicans translocation infection and modified the intestinal microbial community structure and metabolic attributes in model mice. After administering A. muciniphila to the translocation infection group, there was a notable increase in the prevalence of bacteria that produce short-chain fatty acids, including Eubacterium_F. Moreover, there was a significant increase in the levels of specific pathogens, including Faecalibaculum, Turicibacter, and Turicimonas. The study demonstrated that A. muciniphila treatment can improve the composition of intestinal microbiota and metabolites, augment the tight junctions of colonic tissue and diminish systemic inflammatory response. This presents an innovative therapeutic approach for the potential treatment of intestinal C. albicans infection using A. muciniphila.

Metal ion homeostasis regulates condensin-dependent chromatin architecture and chromosome segregation in Schizosaccharomyces pombe
Seong Ho An, Kyoung-Dong Kim
J. Microbiol. 2025;63(9):e2505008.   Published online August 29, 2025
DOI: https://doi.org/10.71150/jm.2505008
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AbstractAbstract PDFSupplementary Material

Condensin plays a central role in mitotic chromosome organization and segregation by mediating long-range chromatin interactions. However, the extent to which cellular metabolic status influences condensin function remains unclear. To gain insights into the relationship of metal ion homeostasis and the function of condensin, we conducted genome-wide chromatin immunoprecipitation sequencing (ChIP-seq) using Schizosaccharomyces pombe under iron- or zinc-deficient conditions. Under iron- or zinc-deficient conditions, ChIP-seq results revealed a selective reduction in condensin binding at high-affinity target loci, particularly genes regulated by Ace2 and Ams2, while cohesin binding remained largely unaffected. Hi-C analysis showed that iron depletion weakened chromatin interactions at these condensin targets and centromeres, without disrupting global genome architecture. DNA fluorescence in situ hybridization (FISH) confirmed that iron deficiency impaired long-range associations between centromeres and Ace2 target loci at the single-cell level. Notably, iron deficiency led to chromosome segregation defects during mitosis, suggesting that diminished condensin occupancy compromised genome stability. These changes occurred without significant alterations in condensin protein levels or global transcription, indicating a direct effect of metal ion availability on condensin activity. Collectively, our findings revealed a previously unrecognized regulatory axis in which cellular metal ion homeostasis modulated condensin-dependent chromatin organization and mitotic chromosome segregation, offering new insights into the integration of metabolic state with genome maintenance.

Efficient CRISPR-based genome editing for inducible degron systems to enable temporal control of protein function in large double-stranded DNA virus genomes
Kihye Shin, Eui Tae Kim
J. Microbiol. 2025;63(9):e2504008.   Published online August 29, 2025
DOI: https://doi.org/10.71150/jm.2504008
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  • 102 Download
AbstractAbstract PDF

CRISPR-Cas9-based gene editing enables precise genetic modifications. However, its application to human cytomegalovirus (HCMV) remains challenging due to the large size of the viral genome and the essential roles of key regulatory genes. Here, we establish an optimized CRISPR-Cas9 system for precise labeling and functional analysis of HCMV immediate early (IE) genes. By integrating a multifunctional cassette encoding an auxin-inducible degron (AID), a self-cleaving peptide (P2A), and GFP into the viral genome via homology-directed repair (HDR), we achieved efficient knock-ins without reliance on bacterial artificial chromosome (BAC) cloning, a labor-intensive and time-consuming approach. We optimized delivery strategies, donor template designs, and component ratios to enhance HDR efficiency, significantly improving knock-in success rates. This system enables real-time fluorescent tracking and inducible protein degradation, allowing temporal control of essential viral proteins through auxin-mediated depletion. Our approach provides a powerful tool for dissecting the dynamic roles of viral proteins throughout the HCMV life cycle, facilitating a deeper understanding of viral pathogenesis and potential therapeutic targets.

Rubrivirga aquatilis sp. nov. and Rubrivirga halophila sp. nov., isolated from Korean coastal surface seawater
Jisoo Han, Yeonjung Lim, Mirae Kim, Jang-Cheon Cho
J. Microbiol. 2025;63(8):e2504017.   Published online August 13, 2025
DOI: https://doi.org/10.71150/jm.2504017
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AbstractAbstract PDFSupplementary Material

Two Gram-stain-negative, obligately aerobic, non-motile, short rod-shaped bacteria, designated IMCC43871T and IMCC45206T, were isolated from coastal surface seawater collected from the Yellow Sea and the South Sea of Korea, respectively. The two strains shared 99.2% 16S rRNA gene sequence similarity with each other and exhibited ≤ 98.4% similarity to three described Rubrivirga species. Average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between IMCC43871T and IMCC45206T were 88.5% and 36.3%, respectively, confirming that they represent two distinct species. Their ANI (≤ 77.7%) and dDDH (≤ 21.4%) values relative to the type strains of the genus Rubrivirga further supported the recognition of strains IMCC43871T and IMCC45206T as two novel species within the genus. The complete genomes of IMCC43871T (4.17 Mb, 71.8% G + C content) and IMCC45206T (4.17 Mb, 72.8% G + C content) fall within the known genomic range of the genus. Cellular fatty acid, quinone, and polar lipid profiles were consistent with the chemotaxonomic features of the genus Rubrivirga, supporting their affiliation with the genus. Based on phylogenetic, genomic, and phenotypic evidence, strains IMCC43871T and IMCC45206T are proposed as two novel species, Rubrivirga aquatilis sp. nov. and Rubrivirga halophila sp. nov., respectively. The type strains are IMCC43871T (= KCTC 102072T = NBRC 116463T) and IMCC45206T (= KCTC 92925T = NBRC 116172T = CCTCC AB 2023136T).

Review
Extracellular vesicles of Gram-negative and Gram-positive probiotics
Yangyunqi Wang, Chongxu Duan, Xiaomin Yu
J. Microbiol. 2025;63(7):e2506005.   Published online July 31, 2025
DOI: https://doi.org/10.71150/jm.2506005
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  • 160 Download
  • 3 Web of Science
  • 4 Crossref
AbstractAbstract PDF

Extracellular vesicles derived from probiotics have received considerable attention for their pivotal role in bacterial‒host communication. These nanosized, bilayer-encapsulated vesicles carry diverse bioactive molecules, such as proteins, lipids, nucleic acids, and metabolites. Currently, ample evidence has emerged that probiotic extracellular vesicles may modulate several processes of host physiological hemostasis and offer therapeutic benefits. This review examines the biogenesis, composition, and immunomodulatory functions of probiotic-derived extracellular vesicles in probiotic–host interactions, highlighting the therapeutic potential of probiotic extracellular vesicles in the diagnosis and treatment of conditions such as cancer and inflammatory bowel disease. We further summarize the techniques for the separation and purification of extracellular vesicles, providing a methodological foundation for future research and applications. Although the field of probiotic extracellular vesicle research is still in its infancy, the prospects for their application in the biomedical field are broad, potentially emerging as a novel therapeutic approach.

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  • Decoding bacterial extracellular vesicles: A review on isolation and characterization techniques
    Malatesh S. Devati, Apoorva Jnana, Stephen P. Kidd, Slade O. Jensen, T. G. Satheesh Babu, Dinesh Upadhya, Thokur S. Murali
    Archives of Microbiology.2026;[Epub]     CrossRef
  • The supernatant of Lactiplantibacillus plantarum 25 is more effective than extracellular vesicles in alleviating ulcerative colitis and improving intestinal barrier function
    Shuang Gong, Xin Li, Qiong Zhang, Rui Wang, Ruixia Zeng, Yibo Zhang
    Frontiers in Microbiology.2026;[Epub]     CrossRef
  • Standardizing Bacterial Extracellular Vesicle Purification: A Call for Consensus
    Dongsic Choi, Eun-Young Lee
    Journal of Microbiology and Biotechnology.2025;[Epub]     CrossRef
  • Advances in Biological Functions and Applications of Feeding Microorganism-derived Extracellular Vesicles
    Yuanyuan Zhu, Xiaofang Zhang, Xin Feng, Yanyan Huang, Langhong Wang, Huihua Zhang, Xinan Zeng, Zhonglin Tang, Qien Qi
    Probiotics and Antimicrobial Proteins.2025;[Epub]     CrossRef
Full articles
Haloimpatiens sporogenes sp. nov. and Haloimpatiens myeolchijeotgali sp. nov., anaerobic bacteria isolated from Myeolchi-jeot, a traditional Korean fermented anchovy
Yu Jeong Lee, Byung Hee Chun
J. Microbiol. 2025;63(7):e2504009.   Published online July 31, 2025
DOI: https://doi.org/10.71150/jm.2504009
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  • 56 Download
AbstractAbstract PDFSupplementary Material

Two rod-shaped, Gram-positive, spore-forming, motile, and strictly anaerobic bacteria, FM7315T and FM7330T were isolated from Myeolchi-jeot, a traditional Korean fermented anchovy. Phylogenetic and phylogenomic analyses based on the 16S rRNA gene and genome sequences revealed that strains FM7315T and FM7330T represent novel species within the genus Haloimpatiens. The genome sizes of strains FM7315T and FM7330T were 3,052,517 bp and 4,194,114 bp, respectively, with G + C contents of 29.7 mol% and 28.0 mol%, respectively. Strain FM7315T exhibited growth at 20–37°C, 0–2% NaCl, and pH range of 5.0–8.0, whereas strain FM7330T grew at 25–45°C, 0–4% NaCl, and pH range of 5.0–9.0. Strain FM7315T contains C14:0, C16:0, C18:1 ω9c, Summed Feature 3 (C16:1 ω7c/C16:1 ω6c), and Summed Feature 8 (C18:1 ω7c/C18:1 ω6c) as major fatty acids, along with diphosphatidylglycerol, phosphatidylglycerol, glycolipid, two aminophospholipids, and five unidentified lipids. Strain FM7330T contains C16:0, C17:1 ω8c, and C18:1 ω9c as major fatty acids, along with diphosphatidylglycerol, two phosphatidylglycerols, four aminophospholipids, and six unidentified lipids. Based on their phenotypic, chemotaxonomic, and molecular characteristics, strains FM7315T and FM7330T represent two novel species of the genus Haloimpatiens, for which the names Haloimpatiens sporogenes sp. nov. (FM7315T = KCTC 25939T = JCM 37574T) and Haloimpatiens myeolchijeotgali sp. nov. (FM7330T = KCTC 25938T = JCM 37575T) have been proposed.

Prebiotic potential of proso millet and quinoa: Effects on gut microbiota composition and functional metabolic pathways
Jinwoo Kim, Jiwoon Kim, Yewon Jung, Gyungcheon Kim, Seongok Kim, Hakdong Shin
J. Microbiol. 2025;63(7):e2503002.   Published online July 31, 2025
DOI: https://doi.org/10.71150/jm.2503002
  • 2,831 View
  • 104 Download
AbstractAbstract PDFSupplementary Material

Prebiotics are indigestible dietary components that improve host health by stimulating the growth and metabolic activity of beneficial intestinal microbes. The whole grains are rich in non-digestible carbohydrates, which may confer prebiotic potential. Among them, millet and quinoa have gained attention as dietary alternatives due to the growing popularity of gluten-free diets. In this study, we examined the effects of proso millet and quinoa on the human gut microbiota using an in vitro fecal incubation model. Both grains altered alpha diversity metrics, including microbial richness, evenness, and phylogenetic diversity. Beta diversity analysis showed that the proso millet and quinoa treatment groups exhibited distinct clustering patterns compared to the control, highlighting their impact on microbial community structure. Taxonomic analysis showed an increase in beneficial genera, including Bifidobacterium, and a decrease in taxa such as Enterobacteriaceae and Flavonifractor. To assess metabolic changes associated with microbial fermentation, short-chain fatty acid (SCFA) intensities were measured. The intensities of acetic acid, propionic acid, and butyric acid were significantly higher in the proso millet- and quinoa-treated groups compared to the control group. Spearman correlation analysis showed that the abundances of Bifidobacterium and Blautia were significantly positively associated with SCFA intensities. Furthermore, predicted functional pathway analysis identified enrichment of carbohydrate-related pathways in proso millet and quinoa treatments. Quinoa supplementation led to a broader enhancement of metabolic pathways, including glycolysis/gluconeogenesis, starch and sucrose metabolism, and pentose phosphate pathways, whereas proso millet enriched galactose metabolism, and starch and sucrose metabolism. These findings suggest that proso millet and quinoa influence gut microbial diversity, composition, and function.

Review
Metabolic engineering of Saccharomyces cerevisiae for efficient utilization of pectin-rich biomass
Dahye Lee, Fransheska Semidey, Luping Xu, Eun Joong Oh
J. Microbiol. 2025;63(7):e2503001.   Published online July 31, 2025
DOI: https://doi.org/10.71150/jm.2503001
  • 3,664 View
  • 107 Download
AbstractAbstract PDF

Pectin-rich biomass, derived from fruit and citrus processing waste, presents a promising yet underutilized resource for sustainable biofuel and biochemical production. Its low lignin content and high concentrations of fermentable sugars, including D-galacturonic acid, L-arabinose, and D-xylose, make it an attractive feedstock. Unlike lignocellulosic biomass, pectin-rich hydrolysates require milder pretreatment, improving sugar recovery efficiency. However, industrial strains such as Saccharomyces cerevisiae exhibit strong glucose preference, limiting the efficient co-fermentation of mixed sugars. While prior reviews have broadly addressed lignocellulosic biomass utilization, this mini-review uniquely centers on the specific metabolic challenges and opportunities associated with pectin-rich feedstocks. In addition to incorporating established strategies for the co-utilization of cellobiose and xylose, we highlight recent advances that allow S. cerevisiae to metabolize carbon sources specifically from pectin-rich biomass, such as L-arabinose and D-galacturonic acid—monomers not prevalent in traditional lignocellulosic biomass. By integrating discussions on sugar transport engineering, redox balancing, and pathway optimization, this review offers a comprehensive framework to overcome glucose repression and support efficient co-fermentation of carbon sources from conventional and pectin-rich biomass. Drawing on these advances, we outline practical strategies to enhance fermentation performance and expand the valorization of food processing residues in biomanufacturing.

Full articles
Efficient and modular reverse genetics system for rapid generation of recombinant severe acute respiratory syndrome coronavirus 2
Sojung Bae, Jinjong Myoung
J. Microbiol. 2025;63(7):e2504015.   Published online July 21, 2025
DOI: https://doi.org/10.71150/jm.2504015
  • 3,585 View
  • 403 Download
AbstractAbstract PDF

The global spread of COVID-19 has underscored the urgent need for advanced tools to study emerging coronaviruses. Reverse genetics systems have become indispensable for dissecting viral gene functions, developing live-attenuated vaccine candidates, and identifying antiviral targets. In this study, we describe a robust and efficient reverse genetics platform for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The system is based on the assembly of a full-length infectious cDNA clone from seven overlapping fragments, each flanked by homologous sequences to facilitate seamless assembly using the Gibson assembly method. Individual cloning of each fragment into plasmids enables modular manipulation of the viral genome, allowing rapid site-directed mutagenesis by fragment exchange. Infectious recombinant virus was successfully recovered from the assembled cDNA, exhibiting uniform plaque morphology and genetic homogeneity compared to clinical isolates. Additionally, fluorescent reporter viruses were generated to enable real-time visualization of infection, and the effects of different mammalian promoters on viral rescue were evaluated. This reverse genetics platform enables efficient generation and manipulation of recombinant SARS-CoV-2, providing a valuable resource for virological research and the development of preventive and therapeutic antiviral measures.

Inhibition of candidalysin production by methoxy-apo-enterobactin from Streptomyces ambofaciens CJD34 as a novel antifungal strategy against Candida albicans
Eui-Seong Kim, Hyeongju Jeong, Mustansir Abbas, Soohyun Um, Juntack Oh, Kyuho Moon, Kyung-Tae Lee
J. Microbiol. 2025;63(6):e2504019.   Published online June 30, 2025
DOI: https://doi.org/10.71150/jm.2504019
  • 1,472 View
  • 69 Download
AbstractAbstract PDF

Opportunistic fungal pathogens, responsible for over 300 million severe cases and 1.5 million deaths annually, pose a serious global health threat, especially in immunocompromised individuals. Among these, Candida albicans is a major cause of both superficial and invasive infections, which can progress to systemic candidiasis. One of the critical factors in C. albicans pathogenicity is the yeast-to-hyphal transition, which enables biofilm formation and promotes tissue invasion through the secretion of candidalysin, a cytolytic peptide toxin encoded by the ECE1 gene. In this study, metabolites produced by Streptomyces ambofaciens CJD34, isolated from soil samples, were screened for antifungal activity. Methoxy-apo-enterobactin (compound 1) was identified as a potential inhibitor of C. albicans virulence. Treatment with compound 1 significantly suppressed ECE1 expression and candidalysin production. In a murine subcutaneous infection model, topical application of compound 1 reduced subcutaneous colonization by C. albicans. Molecular docking analysis suggested that the inhibition of ECE1 expression was not mediated by direct binding to known upstream transcription factors, indicating an indirect mechanism of action. Collectively, these findings highlight compound 1 as a promising antivirulence agent targeting candidalysin-mediated pathogenicity in C. albicans.

Phycobium rhodophyticola gen. nov., sp. nov. and Aliiphycobium algicola gen. nov., sp. nov., isolated from the phycosphere of marine red algae
Jeong Min Kim, Woonhee Baek, Byeong Jun Choi, Hülya Bayburt, Jae Kyeong Lee, Sung Chul Lee, Che Ok Jeon
J. Microbiol. 2025;63(6):e2503014.   Published online June 30, 2025
DOI: https://doi.org/10.71150/jm.2503014
  • 3,245 View
  • 80 Download
  • 4 Web of Science
  • 6 Crossref
AbstractAbstract PDFSupplementary Material

Two Gram-stain-negative, strictly aerobic, non-motile, rod-shaped bacteria, designated D3-12ᵀ and G2-2ᵀ, were isolated from the phycosphere of marine red algae. Both strains exhibited catalase- and oxidase-positive activities. Strain D3-12ᵀ grew optimally at 30°C, pH 7.0, and 2.0–3.0% (w/v) NaCl, while strain G2-2ᵀ showed optimal growth at 30°C, pH 7.0, and 2.0% NaCl. Ubiquinone-10 was the sole respiratory quinone in both strains. The major fatty acids (> 5%) in strain D3-12ᵀ were feature 8 (C18:1 ω7c and/or C18:1 ω6c), 11-methyl-C18:1 ω7c, and C16:0, while strain G2-2ᵀ contained summed feature 8 and C16:0. The predominant polar lipids in strain D3-12ᵀ were phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine, whereas strain G2-2ᵀ contained phosphatidylglycerol and diphosphatidylglycerol. The genomic DNA G + C content was 59.9% for strain D3-12ᵀ and 60.2% for strain G2-2ᵀ. Phylogenetic analyses based on 16S rRNA and whole-genome sequences placed both strains into distinct lineages within the family Roseobacteraceae, separate from previously described genera. Genome-based relatedness metrics, including average nucleotide identity, digital DNA-DNA hybridization, average amino acid identity, and percentage of conserved proteins, further confirmed that these strains represent novel genera. Based on phenotypic, chemotaxonomic, and molecular characteristics, strains D3-12ᵀ and G2-2ᵀ are proposed as novel genera: Phycobium rhodophyticola gen. nov., sp. nov. (D3-12ᵀ = KACC 22712ᵀ = JCM 35528ᵀ) and Aliiphycobium algicola gen. nov., sp. nov. (G2-2ᵀ = KACC 22602ᵀ = JCM 35752ᵀ). Additionally, metabolic features relevant to interactions with marine algae, including genes associated with carbohydrate-active enzymes, vitamin biosynthesis, phenylacetic acid production, and bacterioferritin synthesis, were bioinformatically investigated.

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  • Ningiella algicola sp. nov. and Marinicella algicola sp. nov., proposal of Paralteromonas gen. Nov. and Neoalteromonas gen. Nov. with reclassification of Alteromonas species, and reclassification of Methylophaga aminisulfidivorans as a later heterotypic s
    Hülya Bayburt, Jeong Min Kim, Byeong Jun Choi, Jae Kyeong Lee, Che Ok Jeon
    Systematic and Applied Microbiology.2026; 49(1): 126685.     CrossRef
  • Mucilaginibacter aureus sp. nov. and Mucilaginibacter sediminis sp. nov., isolated from wetland soil
    Chae Yeong Moon, Jae Kyeong Lee, Dong Min Han, Dae Seung Lee, Byeong Jun Choi, Ju Hye Baek, Che Ok Jeon
    International Journal of Systematic and Evolutionary Microbiology .2026;[Epub]     CrossRef
  • Aquimarina rhodophyticola sp. nov. and Aquimarina besae sp. nov., Isolated from Marine Red Algae
    Jeong Min Kim, Byeong Jun Choi, Hülya Bayburt, Dong Min Han, Che Ok Jeon
    Current Microbiology.2025;[Epub]     CrossRef
  • Carotenoid-Producing Qipengyuania algicola sp. nov. and Qipengyuania rhodophyticola sp. nov., Isolated from Marine Algae, and Emended Description of the Genus Qipengyuania Xu et al. 2020
    Jae Kyeong Lee, Min Woo Lee, Chae Yeong Moon, Jeong Min Kim, Hülya Bayburt, Byeong Jun Choi, Che Ok Jeon
    Journal of Microbiology and Biotechnology.2025;[Epub]     CrossRef
  • Flagellimonas ulvae sp. nov. and Flagellimonas rhodophyticola sp. nov., isolated from marine algae
    Hui Seong Won, Dong Min Han, Jeong Min Kim, Hülya Bayburt, Byeong Jun Choi, Zhe-Xue Quan, Che Ok Jeon
    International Journal of Systematic and Evolutionary Microbiology .2025;[Epub]     CrossRef
  • Validation List no. 226: valid publication of new names and new combinations effectively published outside the IJSEM
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    International Journal of Systematic and Evolutionary Microbiology .2025;[Epub]     CrossRef
Review
Targeting innate immune sensors for therapeutic strategies in infectious diseases
Seyun Shin, Young Ki Choi, SangJoon Lee
J. Microbiol. 2025;63(6):e2503009.   Published online June 30, 2025
DOI: https://doi.org/10.71150/jm.2503009
  • 3,701 View
  • 99 Download
  • 3 Web of Science
  • 3 Crossref
AbstractAbstract PDF

The innate immune system relies on innate immune sensors, such as pattern recognition receptors (PRRs), to detect pathogens and initiate immune responses, crucial for controlling infections but also implicated in inflammatory diseases. These innate immune sensors, including Toll-like receptors (TLRs), nod-like receptors (NLRs), RIG-I-like receptors (RLRs), absent in melanoma 2 (AIM2), and Z-DNA binding protein 1 (ZBP1) trigger signaling pathways that produce cytokines, modulating inflammation and cell death. Traditional therapies focus on directly targeting pathogens; however, host-targeting therapeutic strategies have emerged as innovative approaches to modulate innate immune sensor activity. These strategies aim to fine-tune the immune response, either enhancing antiviral defenses or mitigating hyperinflammation to prevent tissue damage. This review explores innate immune sensor-based therapeutic approaches, including inhibitors, agonists, and antagonists, that enhance antiviral defense or suppress harmful inflammation, highlighting innate immune sensors as promising targets in infectious and inflammatory disease treatment.

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    Carbohydrate Polymers.2026; 373: 124660.     CrossRef
  • Z-DNA interaction proteins - insights from ChIP-seq data
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    Cellular & Molecular Immunology.2025; 22(12): 1615.     CrossRef
Full articles
Inhibiting kinesin family member 20A disrupts Zika virus entry by blocking internalization
Jeonghyeon Lee, Younghyun Lim, Hyeong-Rae Kim, Yong-Bin Cho, In-Gu Lee, Young-Jin Seo
J. Microbiol. 2025;63(6):e2503008.   Published online June 30, 2025
DOI: https://doi.org/10.71150/jm.2503008
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Zika virus, a mosquito-borne virus, is associated with congenital birth defects and neurological complications. However, despite its significant public health threat, no approved vaccines or antiviral treatments are currently available. Therefore, this study aims to identify kinesin family member 20A as a key host factor promoting Zika virus life cycle. The elevated expression of kinesin family member 20A following Zika virus infection suggests its role in the viral life cycle. Suppressing its expression through gene silencing or inhibiting its function with a small-molecule inhibitor significantly reduced viral infectivity in host cells. Furthermore, kinesin family member 20A is essential for facilitating viral internalization, a key step in the entry step. These findings suggest its significance in the Zika virus life cycle and highlight its potential as a novel therapeutic target for the Zika virus.

Development of a CRISPR/Cas9 RNP-mediated genetic engineering system in Paecilomyces variotii
Hui-Gang Han, Rutuja Nandre, Hyerang Eom, Yeon-Jae Choi, Hyeon-Su Ro
J. Microbiol. 2025;63(6):e2502011.   Published online June 30, 2025
DOI: https://doi.org/10.71150/jm.2502011
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A thermophilic strain of Paecilomyces variotii (MR1), capable of surviving temperatures above 40°C, was isolated from a paper mill and investigated as a host for heterologous protein production. To prevent environmental dissemination of spores, UV mutagenesis was employed to create a conidia-deficient strain, UM7. This strain underwent gene editing using Cas9-gRNA ribonucleoprotein (RNP) with HR donor DNA fragments, incorporating promoter sequences amplified from the genomic DNA of P. variotii (PH4, PP2, PS8, Ptub, Ptef1, and PgpdA), along with a signal sequence-tagged eGFP, flanked by 5’-upstream (336 bp) and 3’-downstream (363 bp) regions of pyrG. Co-transformation of HR donor DNA with RNP into protoplasts yielded 48 mutant pyrG transformants capable of surviving in the presence of 5-fluoroorotic acid (5-FOA). Sequence analysis identified 16 of the 48 pyrG-disrupted mutants carrying complete HR donor DNAs with the six different promoter sequences, indicating successful homology-directed repair (HDR). Evaluation of promoter strength revealed that PgpdA was the most effective for intracellular GFP production; however, it resulted in negligible extracellular GFP signal under all promoter conditions. A newly edited strain with an HDR integration module connecting PgpdA directly to eGFP, without the signal sequence, exhibited enhanced GFP expression in both mycelial cells and culture broth, suggesting that the signal peptide negatively affect protein expression and secretion. This work represents the first successful RNP-mediated gene editing in P. variotii, contributing to the application of this thermophilic fungus in protein production.


Journal of Microbiology : Journal of Microbiology
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