Journal of Microbiology

Volume 62(6); June 2024

Review

The Role of Extracellular Vesicles in Pandemic Viral Infections.: Woosung Shim, Anjae Lee, Jung-Hyun Lee; J. Microbiol. 2024;62(6):419-427. Published online June 25, 2024; DOI: https://doi.org/10.1007/s12275-024-00144-x

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Abstract: Extracellular vesicles (EVs), of diverse origin and content, are membranous structures secreted by a broad range of cell types. Recent advances in molecular biology have highlighted the pivotal role of EVs in mediating intercellular communication, facilitated by their ability to transport a diverse range of biomolecules, including proteins, lipids, DNA, RNA and metabolites. A striking feature of EVs is their ability to exert dual effects during viral infections, involving both proviral and antiviral effects. This review explores the dual roles of EVs, particularly in the context of pandemic viruses such as HIV-1 and SARS-CoV-2. On the one hand, EVs can enhance viral replication and exacerbate pathogenesis by transferring viral components to susceptible cells. On the other hand, they have intrinsic antiviral properties, including activation of immune responses and direct inhibition of viral infection. By exploring these contrasting functions, our review emphasizes the complexity of EV-mediated interactions in viral pathogenesis and highlights their potential as targets for therapeutic intervention. The insights obtained from investigating EVs in the context of HIV-1 and SARS-CoV-2 provide a deeper understanding of viral mechanisms and pathologies, and offer a new perspective on managing and mitigating the impact of these global health challenges.

Journal Articles

Phylogenetic Assessment of Understudied Families in Hymenochaetales (Basidiomycota, Fungi)-Reporting Uncovered Species and Reflecting the Recent Taxonomic Updates in the Republic of Korea.: Yoonhee Cho, Dohye Kim, Young Woon Lim; J. Microbiol. 2024;62(6):429-447. Published online May 16, 2024; DOI: https://doi.org/10.1007/s12275-024-00120-5

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Abstract: Hymenochaetales Oberw. is an order classified in Basidiomycota of Fungi, and species in this order display notable diversity. They exhibit various fruiting body shapes, including clavarioid, effused-reflexed, and resupinate basidiomes. Few mycorrhizal species have been reported in Hymenochaetales, but wood-decaying species dominate the order. Hymenochaetaceae Imazeki & Toki and Schizoporaceae Jülich are the most species-rich families within Hymenochaetales, and most species in the Republic of Korea belong to these two families. As such, current taxonomic classification and nomenclature are not reflected upon species in the remaining Hymenochaetales families. For this study, a multifaceted morphological and multigenetic marker-based phylogenetic investigation was conducted to, firstly, comprehensively identify understudied Hymenochaetales specimens in Korea and, secondly, reflect the updates on the species classification. Five genetic markers were assessed for the phylogenetic analysis: nuclear small subunit ribosomal DNA (nSSU), internal transcribed spacer (ITS), nuclear large subunit ribosomal DNA (nLSU), RNA polymerase II subunit 2 gene (RPB2), and translation elongation factor 1 gene (TEF1). The results from phylogenetic analysis supported 18 species classified under eight families (excluding Hymenochaetaceae and Schizoporaceae) in Korea. Species formerly placed in Rickenellaceae and Trichaptum sensu lato have been systematically revised based on recent taxonomic reconstructions. In addition, our findings revealed one new species, Rickenella umbelliformis, and identified five formerly nationally unreported species classified under five understudied families. Our findings contribute to a better understanding of Hymenochaetales diversity and highlight the need for continued research.

Quorum Quenching Potential of Reyranella sp. Isolated from Riverside Soil and Description of Reyranella humidisoli sp. nov.: Dong Hyeon Lee, Seung Bum Kim; J. Microbiol. 2024;62(6):449-461. Published online May 30, 2024; DOI: https://doi.org/10.1007/s12275-024-00131-2

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Abstract: Quorum quenching refers to any mechanism that inhibits quorum sensing processes. In this study, quorum quenching activity among bacteria inhabiting riverside soil was screened, and a novel Gram-stain-negative, rod shaped bacterial strain designated MMS21-HV4-11(T), which showed the highest level of quorum quenching activity, was isolated and subjected to further analysis. Strain MMS21-HV4-11(T) could be assigned to the genus Reyranella of Alphaproteobacteria based on the 16S rRNA gene sequence, as the strain shared 98.74% sequence similarity with Reyranella aquatilis seoho-37(T), and then 97.87% and 97.80% sequence similarity with Reyranella soli KIS14-15(T) and Reyranella massiliensis 521(T), respectively. The decomposed N-acyl homoserine lactone was restored at high concentrations under acidic conditions, implying that lactonase and other enzyme(s) are responsible for quorum quenching. The genome analysis indicated that strain MMS21-HV4-11(T) had two candidate genes for lactonase and one for acylase, and expected protein structures were confirmed. In the quorum sensing inhibition assay using a plant pathogen Pectobacterium carotovorum KACC 14888, development of soft rot was significantly inhibited by strain MMS21-HV4-11(T). Besides, the swarming motility by Pseudomonas aeruginosa PA14 was significantly inhibited in the presence of strain MMS21-HV4-11(T). Since the isolate did not display direct antibacterial activity against either of these species, the inhibition was certainly due to quorum quenching activity. In an extended study with the type strains of all known species of Reyranella, all strains were capable of degrading N-acyl homoserine lactones (AHLs), thus showing quorum quenching potential at the genus level. This is the first study on the quorum quenching potential and enzymes responsible in Reyranella. In addition, MMS21-HV4-11(T) could be recognized as a new species through taxonomic characterization, for which the name Reyranella humidisoli sp. nov. is proposed (type strain = MMS21-HV4-11( T) = KCTC 82780( T) = LMG 32365(T)).

Tubulysin Production by the Dead Cells of Archangium gephyra KYC5002.: Seohui Park, Chaehyeon Park, Yujin Ka, Kyungyun Cho; J. Microbiol. 2024;62(6):463-471. Published online June 13, 2024; DOI: https://doi.org/10.1007/s12275-024-00130-3

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Abstract: Archangium gephyra KYC5002 produces tubulysins during the death phase. In this study, we aimed to determine whether dead cells produce tubulysins. Cells were cultured for three days until the verge of the death phase, disrupted via ultrasonication, incubated for 2 h, and examined for tubulysin production. Non-disrupted cells produced 0.14 mg/L of tubulysin A and 0.11 mg/L of tubulysin B. Notably, tubulysin A production was increased by 4.4-fold to 0.62 mg/L and that of tubulysin B was increased by 6.7-fold to 0.74 mg/L in the disrupted cells. The same increase in tubulysin production was observed when the cells were killed by adding hydrogen peroxide. However, when the enzymes were inactivated via heat treatment of the cultures at 65 °C for 30 min, no significant increase in tubulysin production due to cell death was observed. Reverse transcription-quantitative polymerase chain reaction analysis of tubB mRNA revealed that the expression levels of tubulysin biosynthetic enzyme genes increased during the death phase compared to those during the vegetative growth phase. Our findings suggest that A. gephyra produces biosynthetic enzymes and subsequently uses them for tubulysin production in the cell death phase or during cell lysis by predators.

Effects of Feather Hydrolysates Generated by Probiotic Bacillus licheniformis WHU on Gut Microbiota of Broiler and Common carp.: Kamin Ke, Yingjie Sun, Tingting He, Wenbo Liu, Yijiao Wen, Siyuan Liu, Qin Wang, Xiaowei Gao; J. Microbiol. 2024;62(6):473-487. Published online February 29, 2024; DOI: https://doi.org/10.1007/s12275-024-00118-z

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Abstract: Due to the ever-increasing demand for meat, it has become necessary to identify cheap and sustainable sources of protein for animal feed. Feathers are the major byproduct of poultry industry, which are rich in hard-to-degrade keratin protein. Previously we found that intact feathers can be digested into free amino acids, short peptides, and nano-/micro-keratin particles by the strain Bacillus licheniformis WHU in water, and the resulting feather hydrolysates exhibit prebiotic effects on mice. To explore the potential utilization of feather hydrolysate in the feed industry, we investigated its effects on the gut microbiota of broilers and fish. Our results suggest that feather hydrolysates significantly decrease and increase the diversity of gut microbial communities in broilers and fish, respectively. The composition of the gut microbiota was markedly altered in both of the animals. The abundance of bacteria with potentially pathogenic phenotypes in the gut microbial community of the fish significantly decreased. Staphylococcus spp., Pseudomonas spp., Neisseria spp., Achromobacter spp. were significantly inhibited by the feather hydrolysates. In addition, feather hydrolysates significantly improved proteolytic activity in the guts of broilers and fish. In fish, the expression levels of ZO-1 and TGF-α significantly improved after administration of feather hydrolysates. The results presented here suggest that feather hydrolysates generated by B. licheniformis WHU could be an alternative protein source in aquaculture and could exert beneficial effects on fish.

Published Erratum

Erratum: Development of a Novel Korean H9-Specific rRT-PCR Assay and Its Application for Avian Influenza Virus Surveillance in Korea.: Mingeun Sagong, Yong-Myung Kang, Na Yeong Kim, Eun Bi Noh, Gyeong-Beom Heo, Se-Hee An, Youn-Jeong Lee, Young Ki Choi, Kwang-Nyeong Lee; J. Microbiol. 2024;62(6):489-489.; DOI: https://doi.org/10.1007/s12275-024-00149-6

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