Journal of Microbiology

Journal Articles

Congregibacter variabilis sp. nov. and Congregibacter brevis sp. nov. Within the OM60/NOR5 Clade, Isolated from Seawater, and Emended Description of the Genus Congregibacter.: Hyeonsu Tak, Miri S Park, Hyerim Cho, Yeonjung Lim, Jang-Cheon Cho; J. Microbiol. 2024;62(9):739-748. Published online July 18, 2024; DOI: https://doi.org/10.1007/s12275-024-00158-5

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Abstract: Two Gram-stain-negative, aerobic, motile by means of flagella, short rod-shaped bacterial strains, designated IMCC43200(T) and IMCC45268(T), were isolated from coastal seawater samples collected from the South Sea of Korea. Strains IMCC43200(T) and IMCC45268(T) shared 98.6% 16S rRNA gene sequence similarity and were closely related to Congregibacter litoralis KT71(T) (98.8% and 98.7%, respectively). Complete whole-genome sequences of IMCC43200(T) and IMCC45268(T) were 3.93 and 3.86 Mb in size with DNA G + C contents of 54.8% and 54.2%, respectively. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two strains were 74.5% and 23.4%, respectively, revealing that they are independent species. The two strains showed ANI values of ≤ 75.8% and dDDH values of ≤ 23.0% to the type and only species of the genus Congregibacter (C. litoralis), indicating that each strain represents a novel species. Both strains contained summed feature 3 (comprising C(16:1) ω6c and/or C(16:1) ω7c) and summed feature 8 (comprising C(18:1) ω6c and/or C(18:1) ω7c) as major fatty acid constituents. The predominant isoprenoid quinone detected in both strains was ubiquinone-8 (Q-8). The major polar lipids of the two strains were phosphatidylethanolamine, phosphatidylglycerol, phospholipids, and aminolipids. Based on the phylogenetic, genomic, and phenotypic characterization, strains IMCC43200(T) and IMCC45268(T) were considered to represent two novel species within the genus Congregibacter, for which the names Congregibacter variabilis sp. nov. and Congregibacter brevis sp. nov. are proposed with IMCC43200(T) (= KCTC 8133(T) = NBRC 116295(T) = CCTCC AB 2023139(T)) and IMCC45268(T) (= KCTC 92921(T) = NBRC 116135(T)) as the type strains, respectively.

Medium Chain Length Polyhydroxyalkanoate Production by Engineered Pseudomonas gessardii Using Acetate-formate as Carbon Sources.: Woo Young Kim, Seung-Jin Kim, Hye-Rin Seo, Yoonyong Yang, Jong Seok Lee, Moonsuk Hur, Byoung-Hee Lee, Jong-Geol Kim, Min-Kyu Oh; J. Microbiol. 2024;62(7):569-579. Published online May 3, 2024; DOI: https://doi.org/10.1007/s12275-024-00136-x

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Abstract: Production of medium chain length polyhydroxyalkanoate (mcl-PHA) was attempted using Pseudomonas gessardii NIBRBAC000509957, which was isolated from Sunchang, Jeollabuk-do, Republic of Korea (35°24'27.7"N, 127°09'13.0"E) and effectively utilized acetate and formate as carbon sources. We first evaluated the utilization of acetate as a carbon source, revealing optimal growth at 5 g/L acetate. Then, formate was supplied to the acetate minimal medium as a carbon source to enhance cell growth. After overexpressing the acetate and formate assimilation pathway enzymes, this strain grew at a significantly higher rate in the medium. As this strain naturally produces PHA, it was further engineered metabolically to enhance mcl-PHA production. The engineered strain produced 0.40 g/L of mcl-PHA with a biomass content of 30.43% in fed-batch fermentation. Overall, this strain can be further developed to convert acetate and formate into valuable products.

Saxibacter everestensis gen. nov., sp. nov., A Novel Member of the Family Brevibacteriaceae, Isolated from the North Slope of Mount Everest.: Mao Tian, Shiyu Wu, Wei Zhang, Gaosen Zhang, Xue Yu, Yujie Wu, Puchao Jia, Binglin Zhang, Tuo Chen, Guangxiu Liu; J. Microbiol. 2024;62(4):277-284. Published online March 6, 2024; DOI: https://doi.org/10.1007/s12275-024-00108-1

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Abstract: We isolated and analyzed a novel, Gram-stain-positive, aerobic, rod-shaped, non-motile actinobacterium, designated as strain ZFBP1038(T), from rock sampled on the north slope of Mount Everest. The growth requirements of this strain were 10-37 °C, pH 4-10, and 0-6% (w/v) NaCl. The sole respiratory quinone was MK-9, and the major fatty acids were anteiso-C(15:0) and iso-C(17:0). Peptidoglycan containing meso-diaminopimelic acid, ribose, and glucose were the major cell wall sugars, while polar lipids included diphosphatidyl glycerol, phosphatidyl glycerol, an unidentified phospholipid, and an unidentified glycolipid. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain ZFBP1038(T) has the highest similarity with Spelaeicoccus albus DSM 26341( T) (96.02%). ZFBP1038(T) formed a distinct monophyletic clade within the family Brevibacteriaceae and was distantly related to the genus Spelaeicoccus. The G + C content of strain ZFBP1038(T) was 63.65 mol% and the genome size was 4.05 Mb. Digital DNA-DNA hybridization, average nucleotide identity, and average amino acid identity values between the genomes of strain ZFBP1038(T) and representative reference strains were 19.3-25.2, 68.0-71.0, and 52.8-60.1%, respectively. Phylogenetic, phenotypic, and chemotaxonomic characteristics as well as comparative genome analyses suggested that strain ZFBP1038(T) represents a novel species of a new genus, for which the name Saxibacter gen. nov., sp. nov. was assigned with the type strain Saxibacter everestensis ZFBP1038(T) (= EE 014( T) = GDMCC 1.3024( T) = JCM 35335( T)).

Structural and Functional Analyses of the Flavoprotein Disulfide Reductase FN0820 of Fusobacterium nucleatum: Hyunwoo Shin , Yeongjin Baek , Dukwon Lee , Yongbin Xu , Yonghoon Kwon , Inseong Jo , Nam-Chul Ha; J. Microbiol. 2023;61(12):1033-1041. Published online December 20, 2023; DOI: https://doi.org/10.1007/s12275-023-00095-9

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Abstract: Escherichia coli RclA and Staphylococcus aureus MerA are part of the Group I flavoprotein disulfide reductase (FDR) family and have been implicated in the contribution to bacterial pathogenesis by defending against the host immune response. Fusobacterium nucleatum is a pathogenic, anaerobic Gram-negative bacterial species commonly found in the human oral cavity and gastrointestinal tract. In this study, we discovered that the F. nucleatum protein FN0820, belonging to the Group I FDR family, exhibited a higher activity of a Cu2+- dependent NADH oxidase than E. coli RclA. Moreover, FN0820 decreased the dissolved oxygen level in the solution with higher NADH oxidase activity. We found that L-tryptophan and its analog 5-hydroxytryptophan inhibit the FN0820 activities of NADH oxidase and the concomitant reduction of oxygen. Our results have implications for developing new treatment strategies against pathogens that defend the host immune response with Group I FDRs.

Comparison of Ganoderma boninense Isolate’s Aggressiveness Using Infected Oil Palm Seedlings: Mei Lieng Lo , Tu Anh Vu Thanh , Frazer Midot , Sharon Yu Ling Lau , Wei Chee Wong , Hun Jiat Tung , Mui Sie Jee , Mei-Yee Chin , Lulie Melling; J. Microbiol. 2023;61(4):449-459. Published online April 25, 2023; DOI: https://doi.org/10.1007/s12275-023-00040-w

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Abstract: Basal stem rot incidence caused by a white-rot fungus, Ganoderma boninense, is the major disease of oil palm in Southeast Asia. The rate of disease transmission and host damage are affected by variations in pathogen aggressiveness. Several other studies have used the disease severity index (DSI) to determine G. boninense aggressiveness levels while verifying disease using a culture-based method, which might not provide accurate results or be feasible in all cases. To differentiate G. boninense aggressiveness, we employed the DSI and vegetative growth measurement of infected oil palm seedlings. Disease confirmation was performed through scanning electron microscopy and molecular identification of fungal DNA from both infected tissue and fungi isolated from Ganoderma selective medium. Two-month-old oil palm seedlings were artificially inoculated with G. boninense isolates (2, 4A, 5A, 5B, and 7A) sampled from Miri (Lambir) and Mukah (Sungai Meris and Sungai Liuk), Sarawak. The isolates were categorized into three groups: highly aggressive (4A and 5B), moderately aggressive (5A and 7A), and less aggressive (2). Isolate 5B was identified as the most aggressive, and it was the only one to result in seedling mortality. Out of the five vegetative growth parameters measured, only the bole size between treatments was not affected. The integration of both conventional and molecular approaches in disease confirmation allows for precise detection.

Comparison of Conjunctival Sac Microbiome between Low and High Myopic Eyes: Kang Xiao , Zhengyu Chen , Qin Long; J. Microbiol. 2023;61(5):571-578. Published online April 21, 2023; DOI: https://doi.org/10.1007/s12275-023-00045-5

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Abstract: Microbial communities played a vital role in maintaining homeostasis of ocular surface. However, no studies explored the myopia-associated conjunctiva microbiota changes until now. In this study, conjunctival sac swab specimens were collected from 12 eyes of low myopia (LM), and 14 eyes of high myopia (HM) patients. The V3–V4 region of the 16S rRNA gene was amplified and then sequenced. Statistical analysis was performed to investigate differences in the taxonomy and diversity between two groups. Compared to LM, higher Ocular Surface Disease Index (OSDI) scores were observed in HM group. The Shannon index of the HM was lower than that of the LM group (P = 0.017). Principle coordinate analysis and Partial Least Squares Discrimination Analysis showed distinct microbiome composition between two groups. At the phylum level, there were higher relative abundances of Proteobacteria (68.27% vs 38.51%) and lower abundances of Actinobacteria (3.71% vs 9.19%) in HM, compared to LM group (P = 0.031, 0.010, respectively). At the genus level, the abundances of Acinetobacter in HM (18.16%) were significantly higher than the LM (6.52%) group (P = 0.011). Actinobacteria levels were negatively correlated with the myopic spherical equivalent and OSDI scores. Moreover, positive correlations were found between Proteobacteria levels and OSDI scores, Acinetobacter levels were positively correlated with myopic spherical equivalent and OSDI scores. In conclusion, HM Patients have bacterial microbiota imbalance in the conjunctival sac, compared with LM patients. Proteobacteria, Actinobacteria, Acinetobacter may play roles in the HM associated ocular surface irritation.

[Protocol] Development of DNA aptamers specific for small therapeutic peptides using a modified SELEX method: Jaemin Lee , Minkyung Ryu , Dayeong Bae , Hong-Man Kim , Seong-il Eyun , Jeehyeon Bae , Kangseok Lee; J. Microbiol. 2022;60(7):659-667. Published online June 22, 2022; DOI: https://doi.org/10.1007/s12275-022-2235-4

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Abstract: Aptamers are short single-stranded DNA or RNA oligonucleotides capable of binding with high affinity and specificity to target molecules. Because of their durability and ease of synthesis, aptamers are used in a wide range of biomedical fields, including the diagnosis of diseases and targeted delivery of therapeutic agents. The aptamers were selected using a process called systematic evolution of ligands by exponential enrichment (SELEX), which has been improved for various research purposes since its development in 1990. In this protocol, we describe a modified SELEX method that rapidly produces high aptamer screening yields using two types of magnetic beads. Using this method, we isolated an aptamer that specifically binds to an antimicrobial peptide. We suggest that by conjugating a small therapeutic-specific aptamer to a gold nanoparticle-based delivery system, which enhances the stability and intracellular delivery of peptides, aptamers selected by our method can be used for the development of therapeutic agents utilizing small therapeutic peptides.

Integrated proteomic and metabolomic analyses reveal significant changes in chloroplasts and mitochondria of pepper (Capsicum annuum L.) during Sclerotium rolfsii infection: Hongdong Liao , Xiangyu Wen , Xuelei Deng , Yonghong Wu , Jianping Xu , Xin Li , Shudong Zhou , Xuefeng Li , Chunhui Zhu , Feng Luo , Yanqing Ma , Jingyuan Zheng; J. Microbiol. 2022;60(5):511-525. Published online March 31, 2022; DOI: https://doi.org/10.1007/s12275-022-1603-4

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Abstract: Infection by Sclerotium rolfsii will cause serious disease and lead to significant economic losses in chili pepper. In this study, the response of pepper during S. rolfsii infection was explored by electron microscopy, physiological determination and integrated proteome and metabolome analyses. Our results showed that the stomata of pepper stems were important portals for S. rolfsii infection. The plant cell morphology was significantly changed at the time of the fungal hyphae just contacting (T1) or surrounding (T2) the pepper. The chlorophyll, carotenoid, and MDA contents and the activities of POD, SOD, and CAT were markedly upregulated at T1 and T2. Approximately 4129 proteins and 823 metabolites were clearly identified in proteome and metabolome analyses, respectively. A change in 396 proteins and 54 metabolites in pepper stem tissues was observed at T1 compared with 438 proteins and 53 metabolites at T2. The proteins and metabolites related to photosynthesis and antioxidant systems in chloroplasts and mitochondria were disproportionally affected by S. rolfsii infection, impacting carbohydrate and amino acid metabolism. This study provided new insights into the response mechanism in pepper stems during S. rolfsii infection, which can guide future work on fungal disease resistance breeding in pepper.

Geographic diversity in Helicobacter pylori oipA genotype between Korean and United States isolates: Aeryun Kim , Jing Lai , D. Scott Merrell , Ji-Hye Kim , Hanfu Su , Jeong-Heon Cha; J. Microbiol. 2021;59(12):1125-1132. Published online October 31, 2021; DOI: https://doi.org/10.1007/s12275-021-1450-8

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Abstract: Helicobacter pylori outer membrane inflammatory protein A (OipA) was originally named for its role in inducing inflammation in the host, as evidenced by high mucosal IL-8 levels. Expression of OipA is regulated by phase variation of a CT dinucleotide-repeat located in the 5􍿁􀁇region of the gene. However, little is known about OipA geographic diversity across isolates. To address this gap, we conducted a large-scale molecular epidemiologic analysis using H. pylori clinical isolates obtained from two geographically distinct populations: Korea and the United States (US). Most Korean isolates (98.7%) possessed two copies of oipA located at two specific loci (A and B) while all US isolates contained only one copy of oipA at locus A. Furthermore, most Korean oipA (94.8%) possessed three or less CT repeats while most US oipA (96.6%) contained five or more CT repeats. Among the two copies, all Korean H. pylori possessed at least one oipA ‘on’ phase variant while the single copy of oipA in US isolates showed 56.2% ‘on’ and 43.8% ‘off.’ Thus, host differences seem to have driven geographic diversification of H. pylori across these populations such that OipA expression in US isolates is still regulated by phase variation with 5 or more CT repeats, while Korean isolates always express OipA; duplication of the oipA combined with a reduction of CT repeats to three or less ensures continued expression. En masse, these findings suggest that diversity in the oipA gene copy number, CT repeats, and phase variation among H. pylori from different populations may confer a benefit in adaptation to particular host populations.

CagL polymorphisms between East Asian and Western Helicobacter pylori are associated with different abilities to induce IL-8 secretion: Yun Hui Choi , Jing Lai , Myeong-A Kim , Aeryun Kim , Jinmoon Kim , Hanfu Su , Linhu Ge , Jeong-Heon Cha; J. Microbiol. 2021;59(8):763-770. Published online June 1, 2021; DOI: https://doi.org/10.1007/s12275-021-1136-2

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Abstract: Helicobacter pylori colonizes human gastric mucosa. Its infection is associated with gastric diseases including gastric cancer. CagA is one of the most important toxins produced by H. pylori. It is related to gastric cancer which can be injected into host cells via a type IV secretion system (T4SS). CagL is a structural component of T4SS apparatus, which triggers host cell signaling pathway. It has been reported that CagL polymorphisms may influence the severity of disease development. To explore the contribution of CagL polymorphisms between East Asian and Western H. pylori in pathogenesis, cagL gene in G27 H. pylori was swapped by K74 cagL which is identical to East Asian CagL consensus sequence and by Western 26695 H. pylori, resulting in G27ΔcagL/cagLK74 and G27ΔcagL/cagL26695, respectively. Intriguingly, G27ΔcagL/ cagLK74 showed significantly less ability of IL-8 induction than G27ΔcagL/cagL26695 while displayed similar abilities of CagA phosphorylation, and cell elongation. Taken together, this study suggests that the CagL polymorphism may influence IL-8 induction, and K74 CagL has less ability to induce IL-8 secretion than G27 or 26695 CagL. Further research should address how the different capabilities of IL-8 induction between intraspecies-CagL are associated with the large differences of the incidence of gastric cancer between East Asian and Western countries.

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