Journal of Microbiology

Review

The Role of Extracellular Vesicles in Pandemic Viral Infections.: Woosung Shim, Anjae Lee, Jung-Hyun Lee; J. Microbiol. 2024;62(6):419-427. Published online June 25, 2024; DOI: https://doi.org/10.1007/s12275-024-00144-x

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Abstract: Extracellular vesicles (EVs), of diverse origin and content, are membranous structures secreted by a broad range of cell types. Recent advances in molecular biology have highlighted the pivotal role of EVs in mediating intercellular communication, facilitated by their ability to transport a diverse range of biomolecules, including proteins, lipids, DNA, RNA and metabolites. A striking feature of EVs is their ability to exert dual effects during viral infections, involving both proviral and antiviral effects. This review explores the dual roles of EVs, particularly in the context of pandemic viruses such as HIV-1 and SARS-CoV-2. On the one hand, EVs can enhance viral replication and exacerbate pathogenesis by transferring viral components to susceptible cells. On the other hand, they have intrinsic antiviral properties, including activation of immune responses and direct inhibition of viral infection. By exploring these contrasting functions, our review emphasizes the complexity of EV-mediated interactions in viral pathogenesis and highlights their potential as targets for therapeutic intervention. The insights obtained from investigating EVs in the context of HIV-1 and SARS-CoV-2 provide a deeper understanding of viral mechanisms and pathologies, and offer a new perspective on managing and mitigating the impact of these global health challenges.

Journal Articles

The β‑Lactamase Activity at the Community Level Confers β‑Lactam Resistance to Bloom‑Forming Microcystis aeruginosa Ce: Yerim Park , Wonjae Kim , Minkyung Kim , Woojun Park; J. Microbiol. 2023;61(9):807-820. Published online October 18, 2023; DOI: https://doi.org/10.1007/s12275-023-00082-0

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Abstract: Many freshwater cyanobacteria, including Microcystis aeruginosa, lack several known antibiotic resistance genes; however, both axenic and xenic M. aeruginosa strains exhibited high antibiotic resistance against many antibiotics under our tested concentrations, including colistin, trimethoprim, and kanamycin. Interestingly, axenic PCC7806, although not the xenic NIBR18 and NIBR452 strains, displayed susceptibility to ampicillin and amoxicillin, indicating that the associated bacteria in the phycosphere could confer such antibiotic resistance to xenic strains. Fluorescence and scanning electron microscopic observations revealed their tight association, leading to possible community-level β-lactamase activity. Combinatory treatment of ampicillin with a β-lactamase inhibitor, sulbactam, abolished the ampicillin resistance in the xenic stains. The nitrocefin-based assay confirmed the presence of significant community-level β-lactamase activity. Our tested low ampicillin concentration and high β-lactamase activity could potentially balance the competitive advantage of these dominant species and provide opportunities for the less competitive species, thereby resulting in higher bacterial diversity under ampicillin treatment conditions. Non-PCR-based metagenome data from xenic NIBR18 cultures revealed the dominance of blaOXArelated antibiotic resistance genes followed by other class A β-lactamase genes (AST-1 and FAR-1). Alleviation of ampicillin toxicity could be observed only in axenic PCC7806, which had been cocultured with β-lactamase from other freshwater bacteria. Our study suggested M. aeruginosa develops resistance to old-class β-lactam antibiotics through altruism, where associated bacteria protect axenic M. aeruginosa cells.

Chryseobacterium paludis sp. nov. and Chryseobacterium foetidum sp. nov. Isolated from the Aquatic Environment, South Korea: Miryung Kim , Yong&# , Chang&#; J. Microbiol. 2023;61(1):37-47. Published online February 1, 2023; DOI: https://doi.org/10.1007/s12275-022-00008-2

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Abstract: Two novel bacterial species CJ51T and CJ63T belonging to the genus Chryseobacterium were isolated from the Upo wetland and the Han River, South Korea, respectively. Cells of these strains were Gram-stain-negative, aerobic, non-motile, rodshaped, and catalase- and oxidase-positive. Both strains were shown to grow optimally at 30 °C and pH 7 in the absence of NaCl on tryptic soy agar. Phylogenetic analysis based on 16S rRNA gene sequences showed that strains CJ51T and CJ63T belonged to the genus Chryseobacterium and were most closely related to Chryseobacterium piperi CTMT and Chryseobacterium piscicola VQ-6316sT with 98.47% and 98.46% 16S rRNA sequence similarities, respectively. The average nucleotide identity values of strains CJ51T and CJ63T with its closely related type strains Chryseobacterium piperi CTMT and Chryseobacterium piscicola VQ-6316sT were 81.9% and 82.1%, respectively. The major fatty acids of strains CJ51T and CJ63T were iso-C15:0, iso-C17:0 3-OH and summed feature 9 ( C16:0 10-methyl and/or iso-C17:1ω9c). Menaquinone 6 (MK-6) was identified as the primary respiratory quinone in both strains. The major polar lipids of strains CJ51T and CJ63T were phosphatidylethanolamine and several unidentified amino lipids and lipids. Based on polyphasic taxonomy data, strains CJ51T and CJ63T represent novel species of the genus Chryseobacterium, for which names Chryseobacterium paludis sp. nov. and Chryseobacterium foetidum sp. nov. are proposed respectively. The type strains are CJ51T (= KACC 22749T = JCM 35632T) and CJ63T (= KACC 22750T = JCM 35633T).

Diversity and Dynamics of Marine Arenicolous Fungi in Three Seasides of the Korean Peninsula: Jun Won Lee , Chang Wan Seo , Wonjun Lee , Ji Seon Kim , Ki Hyeong Park , Yoonhee Cho , Young Woon Lim; J. Microbiol. 2023;61(1):63-82. Published online January 30, 2023; DOI: https://doi.org/10.1007/s12275-023-00011-1

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3 Citations

Abstract: Various arenicolous fungal species have been detected from the beach sand in the coastal area. However, little has been revealed regarding their distribution and dynamics. To investigate the overall diversity of marine arenicolous fungi (MAFs) in Korea and whether the composition of MAFs is affected by ocean currents, we isolated and analyzed the fungal community from the western, southern, and eastern seasides of the Korean Peninsula. In total, 603 strains were isolated and identified as 259 species based on appropriate molecular markers for each genus (ITS, BenA, CaM, tef1, and act). The composition of MAFs showed differences among the seasides. Our results indicate that many MAFs inhabit the beach sand on the Korean Peninsula, and the composition of MAFs is also affected by ocean currents flowing along each coast.

Flaviflexus equikiangi sp. nov. isolated from faeces of Equus kiang (Tibetan wild ass) and carrying a class 1 integron gene cassette in its genome: Caixin Yang , Xingxing Lian , Yanpeng Cheng , Yifan Jiao , Jing Yang , Kui Dong , Shan Lu , Xin-He Lai , Dong Jin , Han Zheng , Ji Pu , Suping Wang , Liyun Liu , Jianguo Xu; J. Microbiol. 2022;60(6):585-593. Published online April 18, 2022; DOI: https://doi.org/10.1007/s12275-022-1673-3

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Abstract: Two Gram-stain-positive, catalase-negative, non-spore-forming, cocci-shaped strains (dk850T and JY899) were isolated from the feces of Equus kiang in the Qinghai-Tibet Plateau of China. 16S rRNA gene sequence-based phylogenetic analyses showed that strains dk850T and JY899 belong to the genus Flaviflexus, closest to F. salsibiostraticola KCTC 33148T, F. ciconiae KCTC 49253T and F. huanghaiensis H5T. The DNA G + C content of strain dk850T was 62.9%. The digital DNADNA hybridization values of strain dk850T with the closely related species were below the 70% threshold for species demarcation. The two strains grew best at 28°C on brain heart infusion (BHI) agar with 5% sheep blood. All strains had C18:1ω9c and C16:0 as the major cellular fatty acids. MK-9(H4) was the major menaquinone in strain dk850T. The major polar lipids included diphosphatidylglycerol and an unidentified phospholipid. Strains dk850T and JY899 were identified as carrying a class 1 integron containing the aminoglycoside resistance gene aadA11, both strains were resistant to spectinomycin and streptomycin. Based on several lines of evidence from phenotypic and phylogenetic analyses, strains dk850T and JY899 represent a novel species of the genus Flaviflexus, for which the name Flaviflexus equikiangi sp. nov. is proposed. The type strain is dk850T (= CGMCC 1.16593T = JCM 33598T).

Randomized Controlled Trials

A split face study on the effect of an anti-acne product containing fermentation products of Enterococcus faecalis CBT SL-5 on skin microbiome modification and acne improvement: Hye Sung Han , Sun Hye Shin , Bo-Yun Choi , Nayeon Koo , Sanghyun Lim , Dooheon Son , Myung Jun Chung , Kui Young Park , Woo Jun Sul; J. Microbiol. 2022;60(5):488-495. Published online March 14, 2022; DOI: https://doi.org/10.1007/s12275-022-1520-6

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Abstract: Antibiotic-resistant Cutibacterium acnes and dysbiosis of the skin microbiome are of increasing concern in acne treatment. Enterococcus faecalis, a widely used probiotic, has shown benefits for acne treatment by exerting antimicrobial activity against C. acnes. Therefore, this study aimed to investigate the efficacy and safety of an E. faecalis CBT SL-5-extract-containing lotion in patients with mild-to-moderate acne. Twenty patients were enrolled in this randomized, placebo-controlled, split-face comparative study. Patients were treated with E. faecalis lotion on one side of the face and a vehicle lotion on the other side for 4 weeks. The efficacy outcome measures included improvement in the investigators’ assessment of acne severity, patient satisfaction, changes in skin parameters and diversity of the skin microbiome. The investigators’ assessment score was significantly improved on the test side compared to the control side, after 2 weeks (p = 0.009) and 6 weeks (p < 0.0005). However, TEWL and skin hydration were not significantly different between the two groups. The phylogenetic diversity of the skin microbiota decreased over time in the skin samples of test side. In conclusion, E. faecalis CBT SL-5 extract can be a feasible and well-tolerated option for improving acne severity and skin microbiome dysbiosis in mild-to-moderate acne patients.

Ulmus macrocarpa Hance extract modulates intestinal microbiota in healthy adults: a randomized, placebo-controlled clinical trial: Kwangmin Kim , Karpagam Veerappan , Nahyun Woo , Bohyeon Park , Sathishkumar Natarajan , Hoyong Chung , Cheolmin Kim , Junhyung Park; J. Microbiol. 2021;59(12):1150-1156. Published online October 26, 2021; DOI: https://doi.org/10.1007/s12275-021-1329-8

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6 Citations

Abstract: The stem and root bark of Ulmus macrocarpa Hance has been used as traditional pharmacological agent against inflammation related disorders. The objective of this study was to explore the impact of Ulmus macrocarpa Hance extract (UME) on human gut microbiota. A randomized placebo-controlled clinical study was conducted in healthy adults. The study subjects were given 500 mg/day of UME or placebo orally for 4 weeks. Eighty fecal samples were collected at baseline and 4 weeks of UME or placebo intervention. The gut microbiota variation was evaluated by 16S rRNA profiling. The microbial response was highly personalized, and no statistically significant differences was observed in both species richness and abundance. The number of bacterial species identified in study subjects ranged from 86 to 182 species. The analysis for taxonomical changes revealed an increase in Eubacterium ventriosum, Blautia faecis, Ruminococcus gnavus in the UME group. Functional enrichment of bacterial genes showed an increase in primary and secondary bile acid biosynthesis in UME group. Having known from previous studies Eubacterium regulated bile acid homeostasis in protecting gut microbial architecture and immunity, we suggest that UME supplementation might enhance host immunity by modulating gut microbiota. This is the first stage study and forthcoming clinical studies with larger participants are needed to confirm these findings.

Journal Article

Description of Microbacterium luteum sp. nov., Microbacterium cremeum sp. nov., and Microbacterium atlanticum sp. nov., three novel C50 carotenoid producing bacteria: Fuquan Xie , Siwen Niu , Xihuang Lin , Shengxiang Pei , Li Jiang , Yun Tian , Gaiyun Zhang; J. Microbiol. 2021;59(10):886-897. Published online September 7, 2021; DOI: https://doi.org/10.1007/s12275-021-1186-5

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14 Citations

Abstract: We have identified three Microbacterium strains, A18JL200T, NY27T, and WY121T, that produce C50 carotenoids. Taxonomy shows they represent three novel species. These strains shared < 98.5% 16S rRNA gene sequence identity with each other and were closely related to Microbacterium aquimaris JCM 15625T, Microbacterium yannicii JCM 18959T, Microbacterium ureisolvens CFH S00084T, and Microbacterium hibisci CCTCC AB 2016180T. Digital DNA-DNA hybridization (dDDH) values and average nucleotide identity (ANI) showed differences among the three strains and from their closest relatives, with values ranging from 20.4% to 34.6% and 75.5% to 87.6%, respectively. These values are below the threshold for species discrimination. Both morphology and physiology also differed from those of phylogenetically related Microbacterium species, supporting that they are indeed novel species. These strains produce C50 carotenoids (mainly decaprenoxanthin). Among the three novel species, A18JL200T had the highest total yield in carotenoids (6.1 mg/L or 1.2 mg/g dry cell weight). Unusual dual isoprenoid biosynthetic pathways (methylerythritol phosphate and mevalonate pathways) were annotated for strain A18JL200T. In summary, we found strains of the genus Microbacterium that are potential producers of C50 carotenoids, but their genome has to be investigated further.

Review

[MINIREVIEW]The rapid adaptation of SARS-CoV-2–rise of the variants: transmission and resistance: Sandrine M. Soh , Yeongjun Kim , Chanwoo Kim , Ui Soon Jang , Hye-Ra Lee; J. Microbiol. 2021;59(9):807-818. Published online August 27, 2021; DOI: https://doi.org/10.1007/s12275-021-1348-5

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16 Citations

Abstract: The causative factor of COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is continuously mutating. Interestingly, identified mutations mainly occur in the spike (S) protein which interacts with the ACE2 receptor and is cleaved via serine protease TMPRSS2. Some mutated strains are becoming dominant in various parts of the globe because of increased transmissibility as well as cell entry efficacy. Remarkably, the neutralizing activity of monoclonal antibodies, convalescent sera, and vaccines against the variants has been reported to be significantly reduced. Therefore, the efficacy of various monoclonal antibodies therapy and vaccines against these variants is becoming a great global concern. We herein summarize the current status of SARS-CoV- 2 with gears shifted towards the recent and most common genetic variants in relation to transmission, neutralizing activity, and vaccine efficacy.

Journal Articles

UBCG2: Up-to-date bacterial core genes and pipeline for phylogenomic analysis: Jihyeon Kim , Seong-In Na , Dongwook Kim , Jongsik Chun; J. Microbiol. 2021;59(6):609-615. Published online May 29, 2021; DOI: https://doi.org/10.1007/s12275-021-1231-4

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106 Citations

Abstract: Phylogenomic tree reconstruction has recently become a routine and critical task to elucidate the evolutionary relationships among bacterial species. The most widely used method utilizes the concatenated core genes, universally present in a single-copy throughout the bacterial domain. In our previous study, a bioinformatics pipeline termed Up-to-date Bacterial Core Genes (UBCG) was developed with a set of bacterial core genes selected from 1,429 species covering 28 phyla. In this study, we revised a new bacterial core gene set, named UBCG2, that was selected from the more extensive genome sequence set belonging to 3,508 species spanning 43 phyla. UBCG2 comprises 81 genes with nine Clusters of Orthologous Groups of proteins (COGs) functional categories. The new gene set and complete pipeline are available at http://leb.snu.ac.kr/ubcg2.

Effects of multi-species probiotic supplementation on alcohol metabolism in rats: Tae-Joong Lim , Sanghyun Lim , Jong Hyun Yoon , Myung Jun Chung; J. Microbiol. 2021;59(4):417-425. Published online March 29, 2021; DOI: https://doi.org/10.1007/s12275-021-0573-2

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12 Citations

Abstract: Probiotics are known to protect against liver damage induced by the alcohol and acetaldehyde accumulation associated with alcohol intake. However, there have been few studies of the direct effect of probiotics on alcohol metabolism, and the types of probiotics that were previously analyzed were few in number. Here, we investigated the effects of 19 probiotic species on alcohol and acetaldehyde metabolism. Four probiotic species that had a relatively high tolerance to alcohol and metabolized alcohol and acetaldehyde effectively were identified: Lactobacillus gasseri CBT LGA1, Lactobacillus casei CBT LC5, Bifidobacterium lactis CBT BL3, and Bifidobacterium breve CBT BR3. These species also demonstrated high mRNA expression of alcohol and acetaldehyde dehydrogenases. Pro- AP4, a mixture of these four probiotics species and excipient, was then administered to rats for 2 weeks in advance of acute alcohol administration. The serum alcohol and acetaldehyde concentrations were significantly lower in the ProAP4-administered group than in the control and excipient groups. Thus, the administration of ProAP4, containing four probiotic species, quickly lowers blood alcohol and acetaldehyde concentrations in an alcohol and acetaldehyde dehydrogenasedependent manner. Furthermore, the serum alanine aminotransferase activity, which is indicative of liver damage, was significantly lower in the ProAP4 group than in the control group. The present findings suggest that ProAP4 may be an effective means of limiting alcohol-induced liver damage.

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