Journal of Microbiology

Volume 61(7); July 2023

Review

Microbial Interaction is Among the Key Factors for Isolation of Previous Uncultured Microbes: Chang Yan , Jeffrey S. Owen , Eun-Young Seo , Dawoon Jung , Shan He; J. Microbiol. 2023;61(7):655-662. Published online August 17, 2023; DOI: https://doi.org/10.1007/s12275-023-00063-3

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Abstract: Pure cultivation of microbes is still limited by the challenges of microbial uncultivability, with most microbial strains unable to be cultivated under standard laboratory conditions. The experience accumulated from advanced techniques such as in situ cultivation has identified that microbial interactions exist in natural habitats but are absent in laboratory cultures. These microbial interactions are likely one of the key factors in isolating previously uncultured microbes. The need for better knowledge of the mechanisms operating in microbial interactions has led to various experiments that have utilized microbial interactions in different approaches to microbial cultivation. These new attempts to understand microbial interactions not only present a new perspective on microbial uncultivability but also provide an opportunity to access uncultured phylogenetically novel microbes with their potential biotechnology applications. In this review, we focus on studies of the mechanisms of microbial interaction where the growth of other microbes is affected. Additionally, we review some successful applications of microbial interactions in cultivation methods, an approach that can play an important role in the bioprospecting of untapped microbial resources.

Journal Articles

Environmental Adaptation of Psychrophilic Bacteria Subtercola spp. Isolated from Various Cryospheric Habitats: Hanbyul Lee , Yong-Joon Cho , Ahnna Cho , Ok-Sun Kim; J. Microbiol. 2023;61(7):663-672. Published online August 24, 2023; DOI: https://doi.org/10.1007/s12275-023-00068-y

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Abstract: Subtercola boreus K300T is a novel psychrophilic strain that was isolated from permanently cold groundwater in Finland and has also been found in several places in Antarctica including lake, soil, and rocks. We performed genomic and transcriptomic analyses of 5 strains from Antarctica and a type strain to understand their adaptation to different environments. Interestingly, the isolates from rocks showed a low growth rate and smaller genome size than strains from the other isolation sources (lake, soil, and groundwater). Based on these habitat-dependent characteristics, the strains could be classified into two ecotypes, which showed differences in energy production, signal transduction, and transcription in the clusters of orthologous groups of proteins (COGs) functional category. In addition, expression pattern changes revealed differences in metabolic processes, including uric acid metabolism, DNA repair, major facilitator superfamily (MFS) transporters, and xylose degradation, depending on the nutritional status of their habitats. These findings provide crucial insights into the environmental adaptation of bacteria, highlighting genetic diversity and regulatory mechanisms that enable them to thrive in the cryosphere.

Lactobacillus rhamnosus KBL2290 Ameliorates Gut Inflammation in a Mouse Model of Dextran Sulfate Sodium‑Induced Colitis: Woon-ki Kim , Sung-gyu Min , Heeun Kwon , SungJun Park , Min Jung Jo , GwangPyo Ko; J. Microbiol. 2023;61(7):673-682. Published online June 14, 2023; DOI: https://doi.org/10.1007/s12275-023-00061-5

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Abstract: Ulcerative colitis, a major form of inflammatory bowel disease (IBD) associated with chronic colonic inflammation, may be induced via overreactive innate and adaptive immune responses. Restoration of gut microbiota abundance and diversity is important to control the pathogenesis. Lactobacillus spp., well-known probiotics, ameliorate IBD symptoms via various mechanisms, including modulation of cytokine production, restoration of gut tight junction activity and normal mucosal thickness, and alterations in the gut microbiota. Here, we studied the effects of oral administration of Lactobacillus rhamnosus (L. rhamnosus) KBL2290 from the feces of a healthy Korean individual to mice with DSS-induced colitis. Compared to the dextran sulfate sodium (DSS) + phosphate-buffered saline control group, the DSS + L. rhamnosus KBL2290 group evidenced significant improvements in colitis symptoms, including restoration of body weight and colon length, and decreases in the disease activity and histological scores, particularly reduced levels of pro-inflammatory cytokines and an elevated level of anti-inflammatory interleukin-10. Lactobacillus rhamnosus KBL2290 modulated the levels of mRNAs encoding chemokines and markers of inflammation; increased regulatory T cell numbers; and restored tight junction activity in the mouse colon. The relative abundances of genera Akkermansia, Lactococcus, Bilophila, and Prevotella increased significantly, as did the levels of butyrate and propionate (the major short-chain fatty acids). Therefore, oral L. rhamnosus KBL2290 may be a useful novel probiotic.

UACG: Up‑to‑Date Archaeal Core Genes and Software for Phylogenomic Tree Reconstruction: Seong-In Na , Michael James Bailey , Mauricio Chalita , Jae Hyoung Cho , Jongsik Chun; J. Microbiol. 2023;61(7):683-692. Published online August 11, 2023; DOI: https://doi.org/10.1007/s12275-023-00064-2

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Abstract: In the post-genomic era, phylogenomics is a powerful and routinely-used tool to discover evolutionary relationships between microorganisms. Inferring phylogenomic trees by concatenating core gene sequences into a supermatrix is the standard
method
. The previously released up-to-date bacterial core gene (UBCG) tool provides a pipeline to infer phylogenomic trees using single-copy core genes for the Bacteria domain. In this study, we established up-to-date archaeal core gene (UACG), comprising 128 genes suitable for inferring archaeal phylogenomic trees. To test the gene set, we selected the Haloarcula genus and scrutinized its phylogeny. The phylogeny inferred using the UACG tool was consistent with the orthoANIu dendrogram, whereas the 16S rRNA gene phylogeny showed high intragenomic heterogeneity resulting in phylogenetic discrepancies. The software tool using the UACG set is available at https:// www. ezbio cloud. net/ tools/ uacg.

Antiviral Activity Against SARS‑CoV‑2 Variants Using in Silico and in Vitro Approaches: Hee-Jung Lee , Hanul Choi , Aleksandra Nowakowska , Lin-Woo Kang , Minjee Kim , Young Bong Kim; J. Microbiol. 2023;61(7):703-711. Published online June 26, 2023; DOI: https://doi.org/10.1007/s12275-023-00062-4

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Abstract: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emergence in 2019 led to global health crises and the persistent risk of viral mutations. To combat SARS-CoV-2 variants, researchers have explored new approaches to identifying potential targets for coronaviruses. This study aimed to identify SARS-CoV-2 inhibitors using drug repurposing. In silico studies and network pharmacology were conducted to validate targets and coronavirus-associated diseases to select potential candidates, and in vitro assays were performed to evaluate the antiviral effects of the candidate drugs to elucidate the mechanisms of the viruses at the molecular level and determine the effective antiviral drugs for them. Plaque and cytopathic effect reduction were evaluated, and real-time quantitative reverse transcription was used to evaluate the antiviral activity of the candidate drugs against SARS-CoV-2 variants in vitro. Finally, a comparison was made between the molecular docking binding affinities of fenofibrate and remdesivir (positive control) to conventional and identified targets validated from protein–protein interaction (PPI). Seven candidate drugs were obtained based on the biological targets of the coronavirus, and potential targets were identified by constructing complex disease targets and PPI networks. Among the candidates, fenofibrate exhibited the strongest inhibition effect 1 h after Vero E6 cell infection with SARS-CoV-2 variants. This study identified potential targets for coronavirus disease (COVID-19) and SARS-CoV-2 and suggested fenofibrate as a potential therapy for COVID-19.

Published Erratum

Erratum to: Protective and Pathogenic Role of Humoral Responses in COVID‑19: Uni Park , Nam-Hyuk Cho; J. Microbiol. 2023;61(7):713-713.; DOI: https://doi.org/10.1007/s12275-023-00058-0

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Abstract

Fibroblast Growth Factor 11 Inhibits Hepatitis B Virus Gene Expression Through FXRα Suppression: Mi So Seong , Jeong Ah Jang , Ye Rim Jeong , Ye Bin Kim , Yi Yi Kyaw , Hee Jeong Kong , Jung-Hyun Lee , JaeHun Cheong; J. Microbiol. 2023;61(7): 693-702.; DOI: https://doi.org/10.1007/s12275-023-00065-1

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Abstract: Fibroblast growth factor 11 (FGF11) is a member of the intracellular FGF family, which shows different signal transmission compared with other FGF superfamily members. The molecular function of FGF11 is not clearly understood. In this study, we identified the inhibitory effect of FGF11 on hepatitis B virus (HBV) gene expression through transcriptional suppression. FGF11 decreased the mRNA and protein expression of HBV genes in liver cells. While the nuclear receptor FXRα1 increased HBV promoter transactivation, FGF11 decreased the FXRα-mediated gene induction of the HBV promoter by the FXRα agonist. Reduced endogenous levels of FXRα by siRNA and the dominant negative mutant protein (aa 1–187 without ligand binding domain) of FXRα expression indicated that HBV gene suppression by FGF11 is dependent on FXRα inhibition. In addition, FGF11 interacts with FXRα protein and reduces FXRα protein stability. These results indicate that FGF11 inhibits HBV replicative expression through the liver cell-specific transcription factor, FXRα, and suppresses HBV promoter activity. Our findings may contribute to the establishment of better regimens for the treatment of chronic HBV infections by including FGF11 to alter the bile acid mediated FXR pathway.

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