Journal of Microbiology

Volume 59(4); April 2021

Review

Trans-acting regulators of ribonuclease activity: Jaejin Lee , Minho Lee , Kangseok Lee; J. Microbiol. 2021;59(4):341-359. Published online March 29, 2021; DOI: https://doi.org/10.1007/s12275-021-0650-6

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Abstract: RNA metabolism needs to be tightly regulated in response to changes in cellular physiology. Ribonucleases (RNases) play an essential role in almost all aspects of RNA metabolism, including processing, degradation, and recycling of RNA molecules. Thus, living systems have evolved to regulate RNase activity at multiple levels, including transcription, post-transcription, post-translation, and cellular localization. In addition, various trans-acting regulators of RNase activity have been discovered in recent years. This review focuses on the physiological roles and underlying mechanisms of trans-acting regulators of RNase activity.

Journal Articles

Leucobacter coleopterorum sp. nov., Leucobacter insecticola sp. nov., and Leucobacter viscericola sp. nov., isolated from the intestine of the diving beetles, Cybister brevis and Cybister lewisianus, and emended description of the genus Leucobacter: Dong-Wook Hyun , Hojun Sung , Pil Soo Kim , Ji-Hyun Yun , Jin-Woo Bae; J. Microbiol. 2021;59(4):360-368. Published online January 26, 2021; DOI: https://doi.org/10.1007/s12275-021-0472-6

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9 Citations

Abstract: Three novel bacterial strains, HDW9AT, HDW9BT, and HDW9CT, isolated from the intestine of the diving beetles Cybister lewisianus and Cybister brevis, were characterized as three novel species using a polyphasic approach. The isolates were Gram-staining-positive, strictly aerobic, non-motile, and rod-shaped. They grew optimally at 30°C (pH 7) in the presence of 0.5% (wt/vol) NaCl. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that they belong to the genus Leucobacter and are closely related to L. denitrificans M1T8B10T (98.4–98.7% sequence similarity). Average nucleotide identity (ANI) values among the isolates were 76.4–84.1%. ANI values for the isolates and the closest taxonomic species, L. denitrificans KACC 14055T, were 72.3–73.1%. The isolates showed ANI values of < 76.5% with all analyzable Leucobacter strains in the EzBioCloud database. The genomic DNA G + C content of the isolates was 60.3–62.5%. The polar lipid components were phosphatidylglycerol, diphosphatidylglycerol, and other unidentified glycolipids, phospholipids, and lipids. The major cellular fatty acids were anteiso- C15:0, iso-C16:0, and anteiso-C17:0. MK-10 was the major respiratory quinone, and MK-7 and MK-11 were the minor respiratory quinones. The whole-cell sugar components of the isolates were ribose, glucose, galactose, and mannose. The isolates harbored L-2,4-diaminobutyric acid, L-serine, L-lysine, L-aspartic acid, glycine, and D-glutamic acid within the cell wall peptidoglycan. Based on phylogenetic, phenotypic, chemotaxonomic, and genotypic analyses, strains HDW9AT, HDW9BT, and HDW9CT represent three novel species within the genus Leucobacter. We propose the name Leucobacter coleopterorum sp. nov. for strain HDW9AT (= KACC 21331T = KCTC 49317T = JCM 33667T), the name Leucobacter insecticola sp. nov. for strain HDW9BT (= KACC 21332T = KCTC 49318T = JCM 33668T), and the name Leucobacter viscericola sp. nov. for strain HDW9CT (= KACC 21333T = KCTC 49319T = JCM 33669T).

Inferences in microbial structural signatures of acne microbiome and mycobiome: Jubin Kim , Taehun Park , Hye-Jin Kim , Susun An , Woo Jun Sul; J. Microbiol. 2021;59(4):369-375. Published online February 10, 2021; DOI: https://doi.org/10.1007/s12275-021-0647-1

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16 Citations

Abstract: Acne vulgaris, commonly known as acne, is the most common skin disorder and a multifactorial disease of the sebaceous gland. Although the pathophysiology of acne is still unclear, bacterial and fungal factors are known to be involved in. This study aimed to investigate whether the microbiomes and mycobiomes of acne patients are distinct from those of healthy subjects and to identify the structural signatures of microbiomes related to acne vulgaris. A total of 33 Korean female subjects were recruited (Acne group, n = 17; Healthy group, n = 16), and microbiome samples were collected swabbing the forehead and right cheek. To characterize the fungal and bacterial communities, 16S rRNA V4–V5 and ITS1 region, respectively, were sequenced and analysed using Qiime2. There were no significant differences in alpha and beta diversities of microbiomes between the Acne and Healthy groups. In comparison with the ratio of Cutibacterium to Staphylococcus, the acne patients had higher abundance of Staphylococcus compared to Cutibacterium than the healthy individuals. In network analysis with the dominant microorganism amplicon sequence variants (ASV) (Cutibacterium, Staphylococcus, Malassezia globosa, and Malassezia restricta) Cutibacterium acnes was identified to have hostile interactions with Staphylococcus and Malassezia globosa. Accordingly, this
results
suggest an insight into the differences in the skin microbiome and mycobiome between acne patients and healthy controls and provide possible microorganism candidates that modulate the microbiomes associated to acne vulgaris.

Different distribution patterns of microorganisms between aquaculture pond sediment and water: Lili Dai , Chengqing Liu , Liang Peng , Chaofeng Song , Xiaoli Li , Ling Tao; J. Microbiol. 2021;59(4):376-388. Published online February 25, 2021; DOI: https://doi.org/10.1007/s12275-021-0635-5

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23 Citations

Abstract: Aquatic microorganisms in the sediment and water column are closely related; however, their distribution patterns between these two habitats still remain largely unknown. In this study, we compared sediment and water microeukaryotic and bacterial microorganisms in aquaculture ponds from different areas in China, and analyzed the influencing environmental factors as well as the inter-taxa relationships. We found that bacteria were significantly more abundant than fungi in both sediment and water, and the bacterial richness and diversity in sediment were higher than in water in all the sampling areas, but no significant differences were found between the two habitats for microeukaryotes. Bacterial taxa could be clearly separated through cluster analysis between the sediment and water, while eukaryotic taxa at all classification levels could not. Spirochaetea, Deltaproteobacteria, Nitrospirae, Ignavibacteriae, Firmicutes, Chloroflexi, and Lentimicrobiaceae were more abundantly distributed in sediment, while Betaproteobacteria, Alphaproteobacter, Cyanobacteria, Roseiflexaceae, Dinghuibacter, Cryomorphaceae, and Actinobacteria were more abundant in water samples. For eukaryotes, only Cryptomonadales were found to be distributed differently between the two habitats. Microorganisms in sediment were mainly correlated with enzymes related to organic matter decomposition, while water temperature, pH, dissolved oxygen, and nutrient levels all showed significant correlation with the microbial communities in pond water. Intensive interspecific relationships were also found among eukaryotes and bacteria. Together, our results indicated that eukaryotic microorganisms are distributed less differently between sediment and water in aquaculture ponds compared to bacteria. This study provides valuable data for evaluating microbial distributions in aquatic environments, which may also be of practical use in aquaculture pond management.

Effects of mycosubtilin homolog algicides from a marine bacterium, Bacillus sp. SY-1, against the harmful algal bloom species Cochlodinium polykrikoides: Seong-Yun Jeong , Hong-Joo Son; J. Microbiol. 2021;59(4):389-400. Published online March 29, 2021; DOI: https://doi.org/10.1007/s12275-021-1086-8

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11 Citations

Abstract: The marine bacterium, Bacillus sp. SY-1, produced algicidal compounds that are notably active against the bloom-forming alga Cochlodinium polykrikoides. We isolated three algicidal compounds and identified these as mycosubtilins with molecular weights of 1056, 1070, and 1084 (designated MS 1056, 1070, and 1084, respectively), based on amino acid analyses and 1H, 13C, and two-dimensional nuclear magnetic resonance spectroscopy, including 1H-15N heteronuclear multiple bond correlation analysis. MS 1056 contains a β- amino acid residue with an alkyl side chain of C15, which has not previously been seen in known mycosubtilin families. MS 1056, 1070, and 1084 showed algicidal activities against C. polykrikoides with 6-h LC50 values of 2.3 ± 0.4, 0.8 ± 0.2, and 0.6 ± 0.1 μg/ml, respectively. These compounds also showed significant algicidal activities against other harmful algal bloom species. In contrast, MS 1084 showed no significant growth inhibitory effects against other organisms, including bacteria and microalgae, although does inhibit the growth of some fungi and yeasts. These observations imply that the algicidal bacterium Bacillus sp. SY-1 and its algicidal compounds could play an important role in regulating the onset and development of harmful algal blooms in natural environments.

Effects of the loss of mismatch repair genes on single-strand annealing between divergent sequences in Saccharomyces cerevisiae: Ye-Seul Lim , Ju-Hee Choi , Kyu-Jin Ahn , Min-Ku Kim , Sung-Ho Bae; J. Microbiol. 2021;59(4):401-409. Published online March 29, 2021; DOI: https://doi.org/10.1007/s12275-021-1076-x

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Abstract: Eukaryotic genomes contain many duplicated genes closely located with each other, such as the hexose transporter (HXT) genes in Saccharomyces cerevisiae. They can potentially recombine via single-strand annealing (SSA) pathway. SSA between highly divergent sequences generates heteroduplex DNA intermediates with many mismatches, which can be corrected by mismatch repair (MMR), resulting in recombinant sequences with a single junction point. In this report, we demonstrate that SSA between HXT1 and HXT4 genes in MMR-deficient yeast cells produces recombinant genes with multiple-junctions resulting from alternating HXT1 and HXT4 tracts. The mutations in MMR genes had differential effects on SSA frequencies; msh6Δ mutation significantly stimulated SSA events, whereas msh2Δ and msh3Δ slightly suppressed it. We set up an assay that can identify a pair of recombinant genes derived from a single heteroduplex DNA. As a result, the recombinant genes with multiple-junctions were found to accompany genes with single-junctions. Based on the results presented here, a model was proposed to generate multiple-junctions in SSA pathway involving an alternative short-patch repair system.

Crystal structure of human LC8 bound to a peptide from Ebola virus VP35: Dahwan Lim , Ho-Chul Shin , Joon Sig Choi , Seung Jun Kim , Bonsu Ku; J. Microbiol. 2021;59(4):410-416. Published online February 25, 2021; DOI: https://doi.org/10.1007/s12275-021-0641-7

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Abstract: Zaire ebolavirus, commonly called Ebola virus (EBOV), is an RNA virus that causes severe hemorrhagic fever with high mortality. Viral protein 35 (VP35) is a virulence factor encoded in the EBOV genome. VP35 inhibits host innate immune responses and functions as a critical cofactor for viral RNA replication. EBOV VP35 contains a short conserved motif that interacts with dynein light chain 8 (LC8), which serves as a regulatory hub protein by associating with various LC8-binding proteins. Herein, we present the crystal structure of human LC8 bound to the peptide comprising residues 67−76 of EBOV VP35. Two VP35 peptides were found to interact with homodimeric LC8 by extending the central β- sheets, constituting a 2:2 complex. Structural analysis demonstrated that the intermolecular binding between LC8 and VP35 is mainly sustained by a network of hydrogen bonds and supported by hydrophobic interactions in which Thr73 and Thr75 of VP35 are involved. These findings were verified by binding measurements using isothermal titration calorimetry. Biochemical analyses also verified that residues 67−76 of EBOV VP35 constitute a core region for interaction with LC8. In addition, corresponding motifs from other members of the genus Ebolavirus commonly bound to LC8 but with different binding affinities. Particularly, VP35 peptides originating from pathogenic species interacted with LC8 with higher affinity than those from noninfectious species, suggesting that the binding of VP35 to LC8 is associated with the pathogenicity of the Ebolavirus species.

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.

Influences of genetically perturbing synthesis of the typical yellow pigment on conidiation, cell wall integrity, stress tolerance, and cellulase production in Trichoderma reesei: Weixin Zhang , Ning An , Junqi Guo , Zhixing Wang , Xiangfeng Meng , Weifeng Liu; J. Microbiol. 2021;59(4):426-434. Published online January 26, 2021; DOI: https://doi.org/10.1007/s12275-021-0433-0

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14 Citations

Abstract: The prominent protein producing workhorse Trichoderma reesei secretes a typical yellow pigment that is synthesized by a gene cluster including two polyketide synthase encoding genes sor1 and sor2. Two transcription factors (YPR1 and YPR2) that are encoded in the same cluster have been shown to regulate the expression of the sor genes. However, the physiological relevance of the yellow pigment synthesis in T. reesei is not completely clear. In this study, a yellow pigment hyper-producer OEypr1 and three yellow pigment non-producers, OEypr1-sor1, Δypr1, and OEypr2, were constructed. Their phenotypic features in mycelial growth, conidiation, cell wall integrity, stress tolerance, and cellulase production were determined. Whereas hyperproduction of the yellow pigment caused significant defects in all the physiological aspects tested, the non-producers showed similar colony growth, but improved conidiation, maintenance of cell wall integrity, and stress tolerance compared to the control strain. Moreover, in contrast to the severely compromised extracellular cellobiohydrolase production in the yellow pigment hyperproducer, loss of the yellow pigment hardly affected induced cellulase gene expression. Our results demonstrate that interfering with the yellow pigment synthesis constitutes an engineering strategy to endow T. reesei with preferred features for industrial application.

Molecular mechanism of Escherichia coli H10407 induced diarrhoea and its control through immunomodulatory action of bioactives from Simarouba amara (Aubl.): Hegde Veena , Sandesh K. Gowda , Rajeshwara N. Achur , Nayaka Boramuthi Thippeswamy; J. Microbiol. 2021;59(4):435-447. Published online February 25, 2021; DOI: https://doi.org/10.1007/s12275-021-0423-2

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Abstract: Enterotoxigenic Escherichia coli (ETEC) infection is a major cause of death in children under the age of five in developing countries. ETEC (O78:H11:CFA/I:LT+:ST+) mechanism has been studied in detail with either heat labile (LT) or heat stable (ST) toxins using in vitro and in vivo models. However, there is no adequate information on ETEC pathogenesis producing both the toxins (LT, ST) in BALB/c mice model. In this study, female mice have been employed to understand ETEC H10407 infection induced changes in physiology, biochemical and immunological patterns up to seven days post-infection and the antidiarrhoeal effect of Simarouba amara (Aubl.) bark aqueous extract (SAAE) has also been looked into. The results indicate that BALB/c is sensitive to ETEC infection resulting in altered jejunum and ileum histomorphology. Withal, ETEC influenced cAMP, PGE2, and NO production resulting in fluid accumulation with varied Na+, K+, Cl-, and Ca2+ levels. Meanwhile, ETEC subverted expression of IL-1β, intestine alkaline phosphatase (IAP), and myeloperoxidase (MPO) in jejunum and ileum. Our data also indicate the severity of pathogenesis reduction which might be due to attainment of equilibrium after reaching optimum rate of infection. Nevertheless, degree of pathogenesis was highly significant (p < 0.01) in all the studied parameters. Besides that, SAAE was successful in reducing the infectious diarrhoea by inhibiting ETEC H10407 in intestine (jejunum and ileum), and shedding in feces. SAAE decreased cAMP, PGE2, and fluid accumulation effectively and boosted the functional activity of immune system in jejunum and ileum IAP, MPO, IL-1β, and nitric oxide.

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