Journal of Microbiology

Journal Articles

Licochalcone A Protects Vaginal Epithelial Cells Against Candida albicans Infection Via the TLR4/NF-κB Signaling Pathway.: Wei Li, Yujun Yin, Taoqiong Li, Yiqun Wang, Wenyin Shi; J. Microbiol. 2024;62(7):525-533. Published online May 31, 2024; DOI: https://doi.org/10.1007/s12275-024-00134-z

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Abstract: Vulvovaginal candidiasis (VVC) is a prevalent condition affecting a significant portion of women worldwide. Licochalcone A (LA), a natural compound with diverse biological activities, holds promise as a protective agent against Candida albicans (C. albicans) infection. This study aims to investigate the potential of LA to safeguard vaginal epithelial cells (VECs) from C. albicans infection and elucidate the underlying molecular mechanisms. To simulate VVC in vitro, VK2-E6E7 cells were infected with C. albicans. Candida albicans biofilm formation, C. albicans adhesion to VK2-E6E7 cells, and C. albicans-induced cell damage and inflammatory responses were assessed by XTT reduction assay, fluorescence assay, LDH assay, and ELISA. CCK-8 assay was performed to evaluate the cytotoxic effects of LA on VK2-E6E7 cells. Western blotting assay was performed to detect protein expression. LA dose-dependently hindered C. albicans biofilm formation and adhesion to VK2-E6E7 cells. Furthermore, LA mitigated cell damage, inhibited the Bax/Bcl-2 ratio, and attenuated the secretion of pro-inflammatory cytokines in C. albicans-induced VK2-E6E7 cells. The investigation into LA's impact on the Toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) pathway revealed that LA downregulated TLR4 expression and inhibited NF-κB activation in C. albicans-infected VK2-E6E7 cells. Furthermore, TLR4 overexpression partially abated LA-mediated protection, further highlighting the role of the TLR4/NF-κB pathway. LA holds the potential to safeguard VECs against C. albicans infection, potentially offering therapeutic avenues for VVC management.

Effects of Phosphorus‑dissolving Dark Septate Endophytes on the Growth of Blueberry: Qixin Luo , Rui Hou , Xiaojing Shang , Si Li; J. Microbiol. 2023;61(9):837-851. Published online October 5, 2023; DOI: https://doi.org/10.1007/s12275-023-00080-2

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Abstract: Dark septate endophytes (DSEs) are widely distributed and improve plant growth. DSEs secrete large amounts of enzymes to mineralize insoluble phosphorus in soil and convert it into soluble phosphorus, promoting plant uptake of phosphorus. However, the effects of DSEs with phosphate-solubilizing ability on host plants need further study. In this study, phosphorusdissolving DSEs were screened for growth-promoting effects. We isolated, identified and characterized three DSE species (Thozetella neonivea, Pezicula ericae and Hyaloscyphaceae sp.) showing phosphate-solubilizing ability. The impact of single, dual or triple inoculation of DSEs on blueberry plant characteristics was studied. Their effects on colonization intensity, seedling biomass, nutrients in plants and soil, and activities of plant resistance enzymes and soil enzymes were markedly upregulated relative to the control (P < 0.05). The available phosphorus and acid phosphatase levels in different combinations were significantly increased. These findings indicate that the application of the three DSEs may be valuable in facilitating the cultivation of blueberry with a higher biomass and improved plant quality.

Short-chain fatty acids inhibit the biofilm formation of Streptococcus gordonii through negative regulation of competence-stimulating peptide signaling pathway: Taehwan Park , Jintaek Im , A Reum Kim , Dongwook Lee , Sungho Jeong , Cheol-Heui Yun , Seung Hyun Han; J. Microbiol. 2021;59(12):1142-1149. Published online December 4, 2021; DOI: https://doi.org/10.1007/s12275-021-1576-8

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13 Citations

Abstract: Streptococcus gordonii, a Gram-positive commensal bacterium, is an opportunistic pathogen closely related to initiation and progression of various oral diseases, such as periodontitis and dental caries. Its biofilm formation is linked with the development of such diseases by enhanced resistance against antimicrobial treatment or host immunity. In the present study, we investigated the effect of short-chain fatty acids (SCFAs) on the biofilm formation of S. gordonii. SCFAs, including sodium acetate (NaA), sodium propionate (NaP), and sodium butyrate (NaB), showed an effective inhibitory activity on the biofilm formation of S. gordonii without reduction in bacterial growth. SCFAs suppressed S. gordonii biofilm formation at early time points whereas SCFAs did not affect its preformed biofilm. A quorum-sensing system mediated by competence-stimulating peptide (CSP) is known to regulate biofilm formation of streptococci. Interestingly, SCFAs substantially decreased mRNA expression of comD and comE, which are CSP-sensor and its response regulator responsible for CSP pathway, respectively. Although S. gordonii biofilm formation was enhanced by exogenous synthetic CSP treatment, such effect was not observed in the presence of SCFAs. Collectively, these results suggest that SCFAs have an anti-biofilm activity on S. gordonii through inhibiting comD and comE expression which results in negative regulation of CSP quorum-sensing system. SCFAs could be an effective anti-biofilm agent against S. gordonii for the prevention of oral diseases.

Effects of digested Cheonggukjang on human microbiota assessed by in vitro fecal fermentation: Vineet Singh , Nakwon Hwang , Gwangpyo Ko , Unno Tatsuya; J. Microbiol. 2021;59(2):217-227. Published online February 1, 2021; DOI: https://doi.org/10.1007/s12275-021-0525-x

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13 Citations

Abstract: In vitro fecal fermentation is an assay that uses fecal microbes to ferment foods, the results of which can be used to evaluate the potential of prebiotic candidates. To date, there have been various protocols used for in vitro fecal fermentation- based assessments of food substances. In this study, we investigated how personal gut microbiota differences and external factors affect the results of in vitro fecal fermentation assays. We used Cheonggukjang (CGJ), a Korean traditional fermented soybean soup that is acknowledged as healthy functional diet. CGJ was digested in vitro using acids and enzymes, and then fermented with human feces anaerobically. After fecal fermentation, the microbiota was analyzed using MiSeq, and the amount of short chain fatty acids (SCFAs) were measured using GC-MS. Our results suggest that CGJ was effectively metabolized by fecal bacteria to produce SCFAs, and this process resulted in an increase in the abundance of Coprococcus, Ruminococcus, and Bifidobacterium and a reduction in the growth of Sutterella, an opportunistic pathogen. The metabolic activities predicted from the microbiota shifts indicated enhanced metabolism linked to methionine biosynthesis and depleted chondroitin sulfate degradation. Moreover, the amount of SCFAs and microbiota shifts varied depending on personal microbiota differences. Our findings also suggest that in vitro fecal fermentation of CGJ for longer durations may partially affect certain fecal microbes. Overall, the study discusses the usability of in vitro gastrointestinal digestion and fecal fermentation (GIDFF) to imitate the effects of diet-induced microbiome modulation and its impact on the host.

Review

[MINIREVIEW]Regulation of gene expression by protein lysine acetylation in Salmonella: Hyojeong Koo , Shinae Park , Min-Kyu Kwak , Jung-Shin Lee; J. Microbiol. 2020;58(12):979-987. Published online November 17, 2020; DOI: https://doi.org/10.1007/s12275-020-0483-8

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12 Citations

Abstract: Protein lysine acetylation influences many physiological functions, such as gene regulation, metabolism, and disease in eukaryotes. Although little is known about the role of lysine acetylation in bacteria, several reports have proposed its importance in various cellular processes. Here, we discussed the function of the protein lysine acetylation and the post-translational modifications (PTMs) of histone-like proteins in bacteria focusing on Salmonella pathogenicity. The protein lysine residue in Salmonella is acetylated by the Pat-mediated enzymatic pathway or by the acetyl phosphate-mediated non-enzymatic pathway. In Salmonella, the acetylation of lysine 102 and lysine 201 on PhoP inhibits its protein activity and DNAbinding, respectively. Lysine acetylation of the transcriptional regulator, HilD, also inhibits pathogenic gene expression. Moreover, it has been reported that the protein acetylation patterns significantly differ in the drug-resistant and -sensitive Salmonella strains. In addition, nucleoid-associated proteins such as histone-like nucleoid structuring protein (H-NS) are critical for the gene silencing in bacteria, and PTMs in H-NS also affect the gene expression. In this review, we suggest that protein lysine acetylation and the post-translational modifications of H-NS are important factors in understanding the regulation of gene expression responsible for pathogenicity in Salmonella.

Journal Articles

Differences in the gut microbiota between Cercopithecinae and Colobinae in captivity: Zongjin Huan , Yongfang Yao , Jianqiu Yu , Hongwei Chen , Meirong Li , Chaojun Yang , Bo Zhao , Qingyong Ni , Mingwang Zhang , Meng Xie , Huailiang Xu; J. Microbiol. 2020;58(5):367-376. Published online March 28, 2020; DOI: https://doi.org/10.1007/s12275-020-9493-9

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10 Citations

Abstract: The gut microbiome of captive primates can provide a window into their health and disease status. The diversity and composition of gut microbiota are influenced by not only host phylogeny, but also host diet. Old World monkeys (Cercopithecidae) are divided into two subfamilies: Cercopithecinae and Colobinae. The diet and physiological digestive features differ between these two subfamilies. Accordingly, highthroughput sequencing was used to examine gut microbiota differences between these two subfamilies, using data from 29 Cercopithecinae individuals and 19 Colobinae individuals raised in captivity. Through a comparative analysis of operational taxonomic units (OTUs), significant differences in the diversity and composition of gut microbiota were observed between Cercopithecinae and Colobinae. In particular, the gut microbiota of captive Old World monkeys clustered strongly by the two subfamilies. The Colobinae microbial diversity was higher than that of Cercopithecinae. Additionally, Firmicutes, Lactobacillaceae, Veillonellaceae, and Prevotella abundance were higher in Cercopithecinae, while Bacteroidetes, Ruminococcaceae, Christensenellaceae, Bacteroidaceae, and Acidaminococcaceae abundance were higher in Colobinae. PICRUSt analysis revealed that the predicted metagenomes of metabolic pathways associated with proteins, carbohydrates, and amino acids were significantly higher in Colobinae. In the context of host phylogeny, these differences between Cercopithecinae and Colobinae could reflect adaptations associated with their respective diets. This well-organized dataset is a valuable resource for future related research on primates and gut microbiota. Moreover, this study may provide useful insight into animal management practices and primate conservation.

Jejubacter calystegiae gen. nov., sp. nov., moderately halophilic, a new member of the family Enterobacteriaceae, isolated from beach morning glory: Lingmin Jiang , Dexin Wang , Jung-Sook Lee , Dae-Hyuk Kim , Jae Cheol Jeong , Cha Young Kim , Suk Weon Kim , Jiyoung Lee; J. Microbiol. 2020;58(5):357-366. Published online March 27, 2020; DOI: https://doi.org/10.1007/s12275-020-9294-1

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5 Citations

Abstract: Strain KSNA2T, a Gram-negative, moderately halophilic, facultatively anaerobic, motile, rod-shaped bacterium, was isolated from the surface-sterilized stem tissue of a beach morning glory (Calystegia soldanella) plant in Chuja Island, Jejudo, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene and whole-genome sequences revealed that strain KSNA2T formed a distinct lineage within the family Enterobacteriaceae, with the highest 16S rRNA gene sequence similarity to Izhakiella australiensis KCTC 72143T (96.2%) and Izhakiella capsodis KCTC 72142T (96.0%), exhibited 95.5– 95.9% similarity to other genera in the family Enterobacteriaceae and Erwiniaceae. Conserved signature indels analysis elucidated that strain KSNA2T was delimited into family Enterobacteriaceae. KSNA2T genome comprises a circular chromosome of 5,182,800 bp with 56.1% G + C content. Digital DNA-DNA relatedness levels between strain KSNA2T and 18 closely related species were 19.3 to 21.1%. Average nucleotide identity values were between 72.0 and 76.7%. Growth of strain KSNA2T was observed at 4 to 45°C (optimum, 25°C) and pH 5.0 to 12.0 (optimum, pH 7.0) in the presence of 0 to 11% (w/v) NaCl (optimum, 0–7%). The major cellular fatty acids (> 10%) were C16:0 followed by summed feature 8 (C18:1 ω7c and/or C18:1 ω6c), summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), C17:0 cyclo, and C14:0. The major isoprenoid quinone was ubiquinone-8 (Q-8). With combined phylogenetic, genomic, phenotypic, and chemotaxonomic features, strain KSNA2T represents a novel species of a new genus in the family Enterobacteriaceae, for which the name Jejubacter calystegiae gen. nov., sp. nov. is proposed. The type strain is KSNA2T (= KCTC 72234T = CCTCC AB 2019098T).

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