Journal of Microbiology

Journal Articles

Coumarin-based combined computational study to design novel drugs against Candida albicans: Akhilesh Kumar Maurya , Nidhi Mishra; J. Microbiol. 2022;60(12):1201-1207. Published online November 10, 2022; DOI: https://doi.org/10.1007/s12275-022-2279-5

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Abstract: Candida species cause the most prevalent fungal illness, candidiasis. Candida albicans is known to cause bloodstream infections. This species is a commensal bacterium, but it can cause hospital–acquired diseases, particularly in COVID-19 patients with impaired immune systems. Candida infections have increased in patients with acute respiratory distress syndrome. Coumarins are both naturally occurring and synthetically produced. In this study, the biological activity of 40 coumarin derivatives was used to create a three-dimensional quantitative structure activity relationship (3D-QSAR) model. The training and test minimum inhibitory concentration values of C. albicans active compounds were split, and a regression model based on statistical data was established. This model served as a foundation for the creation of coumarin derivative QSARs. This is a unique way to create new therapeutic compounds for various ailments. We constructed novel structural coumarin derivatives using the derived QSAR model, and the models were confirmed using molecular docking and molecular dynamics simulation.

Enhancement of the solubility of recombinant proteins by fusion with a short-disordered peptide: Jun Ren , Suhee Hwang , Junhao Shen , Hyeongwoo Kim , Hyunjoo Kim , Jieun Kim , Soyoung Ahn , Min-gyun Kim , Seung Ho Lee , Dokyun Na; J. Microbiol. 2022;60(9):960-967. Published online July 14, 2022; DOI: https://doi.org/10.1007/s12275-022-2122-z

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Abstract: In protein biotechnology, large soluble fusion partners are widely utilized for increased yield and solubility of recombinant proteins. However, the production of additional large fusion partners poses an additional burden to the host, leading to a decreased protein yield. In this study, we identified two highly disordered short peptides that were able to increase the solubility of an artificially engineered aggregationprone protein, GFP-GFIL4, from 0.6% to 61% (D3-DP00592) and 46% (D4-DP01038) selected from DisProt database. For further confirmation, the peptides were applied to two insoluble E. coli proteins (YagA and YdiU). The peptides also enhanced solubility from 52% to 90% (YagA) and from 27% to 93% (YdiU). Their ability to solubilize recombinant proteins was comparable with strong solubilizing tags, maltosebinding protein (40 kDa) and TrxA (12 kDa), but much smaller (< 7 kDa) in size. For practical application, the two peptides were fused with a restriction enzyme, I-SceI, and they increased I-SceI solubility from 24% up to 75%. The highly disordered peptides did not affect the activity of I-SceI while I-SceI fused with MBP or TrxA displayed no restriction activity. Despite the small size, the highly disordered peptides were able to solubilize recombinant proteins as efficiently as conventional fusion tags and did not interfere with the function of recombinant proteins. Consequently, the identified two highly disordered peptides would have practical utility in protein biotechnology and industry.

A mucin-responsive hybrid two-component system controls Bacteroides thetaiotaomicron colonization and gut homeostasis: Ju-Hyung Lee , Soo-Jeong Kwon , Ji-Yoon Han , Sang-Hyun Cho , Yong-Joon Cho , Joo-Hong Park; J. Microbiol. 2022;60(2):215-223. Published online February 1, 2022; DOI: https://doi.org/10.1007/s12275-022-1649-3

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Abstract: The mammalian intestinal tract contains trillions of bacteria. However, the genetic factors that allow gut symbiotic bacteria to occupy intestinal niches remain poorly understood. Here, we identified genetic determinants required for Bacteroides thetaiotaomicron colonization in the gut using transposon sequencing analysis. Transposon insertion in BT2391, which encodes a hybrid two-component system, increased the competitive fitness of B. thetaiotaomicron. The BT2391 mutant showed a growth advantage in a mucin-dependent manner and had an increased ability to adhere to mucus-producing cell lines. The increased competitive advantage of the BT2391 mutant was dependent on the BT2392–2395 locus containing susCD homologs. Deletion of BT2391 led to changes in the expression levels of B. thetaiotaomicron genes during gut colonization. However, colonization of the BT2391 mutant promoted DSS colitis in low-fiber diet-fed mice. These results indicate that BT2391 contributes to a sustainable symbiotic relationship by maintaining a balance between mucosal colonization and gut homeostasis.

Characterization of a novel phage depolymerase specific to Escherichia coli O157:H7 and biofilm control on abiotic surfaces: Do-Won Park , Jong-Hyun Park; J. Microbiol. 2021;59(11):1002-1009. Published online October 6, 2021; DOI: https://doi.org/10.1007/s12275-021-1413-0

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Abstract: The increasing prevalence of foodborne diseases caused by Escherichia coli O157:H7 as well as its ability to form biofilms poses major threats to public health worldwide. With increasing concerns about the limitations of current disinfectant treatments, phage-derived depolymerases may be used as promising biocontrol agents. Therefore, in this study, the characterization, purification, and application of a novel phage depolymerase, Dpo10, specifically targeting the lipopolysaccharides of E. coli O157, was performed. Dpo10, with a molecular mass of 98 kDa, was predicted to possess pectate lyase activity via genome analysis and considered to act as a receptor- binding protein of the phage. We confirmed that the purified Dpo10 showed O-polysaccharide degrading activity only for the E. coli O157 strains by observing its opaque halo. Dpo10 maintained stable enzymatic activities across a wide range of temperature conditions under 55°C and mild basic pH. Notably, Dpo10 did not inhibit bacterial growth but significantly increased the complement-mediated serum lysis of E. coli O157 by degrading its O-polysaccharides. Moreover, Dpo10 inhibited the biofilm formation against E. coli O157 on abiotic polystyrene by 8-fold and stainless steel by 2.56 log CFU/coupon. This inhibition was visually confirmed via fieldemission scanning electron microscopy. Therefore, the novel depolymerase from E. coli siphophage exhibits specific binding and lytic activities on the lipopolysaccharide of E. coli O157 and may be used as a promising anti-biofilm agent against the E. coli O157:H7 strain.

Lentibacillus cibarius sp. nov., isolated from kimchi, a Korean fermented food: Young Joon Oh , Joon Yong Kim , Hee Eun Jo , Hyo Kyeong Park , Seul Ki Lim , Min-Sung Kwon , Hak-Jong Choi; J. Microbiol. 2020;58(5):387-394. Published online April 11, 2020; DOI: https://doi.org/10.1007/s12275-020-9507-7

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Abstract: Two bacterial strains designated NKC220-2T and NKC851-2 were isolated from commercial kimchi from different areas in Korea. The strains were Gram-positive, aerobic, oxidaseand catalase-positive, rod-shaped, spore-forming, non-motile, and halophilic bacteria. Both strains grew without NaCl, unlike type species in the genus Lentibacillus. The optimal pH for growth was 8.0, higher than that of the type species in the genus Lentibacillus, although growth was observed at pH 5.5–9.0. 16S rRNA gene sequence-based phylogenetic analysis indicated that the two strains (99.3–99.9% similarity) are grouped within the genus Lentibacillus and most closely related to Lentibacillus juripiscarius IS40-3T (97.4–97.6% similarity) isolated from fish sauce in Thailand. OrthoANI value between two novel strains and Lentibacillus lipolyticus SSKP1- 9T (79.5–79.6% similarity) was far lower than the species demarcation threshold. Comparative genomic analysis displayed differences between the two strains as well as among other strains belonging to Lentibacillus. Furthermore, each isolate had strain-specific groups of orthologous genes based on pangenome analysis. Genomic G + C contents of strains NKC- 220-2T and NKC851-2 were 41.9 and 42.2 mol%, respectively. The strains contained meso-diaminopimelic acid in their cell walls, and the major menaquinone was menaquinone-7. Phosphatidylglycerol, diphosphatidylglycerol, and an unidentified glycolipid, aminophospholipid, and phospholipid were the major polar lipid components of both strains. The major cellular fatty acids of the strains were anteiso-C15:0 and anteiso- C17:0. Based on phenotypic, genomic, phylogenetic, and chemotaxonomic features, strains NKC220-2T and NKC851-2 represent novel species of the genus Lentibacillus, for which the name Lentibacillus cibarius sp. nov. is proposed. The type strain is NKC220-2T (= KACC 21232T = JCM 33390T).

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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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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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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