Journal of Microbiology

Journal Articles

Enhanced Poly-γ-Glutamic Acid Production by a Newly Isolated Bacillus halotolerans F29.: Xiaorong Sun, Yaoyu Cai, Dexin Wang; J. Microbiol. 2024;62(8):695-707. Published online August 20, 2024; DOI: https://doi.org/10.1007/s12275-024-00153-w

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Abstract: Poly-γ-glutamic acid (γ-PGA) is a promising biopolymer for various applications. In this study, we isolated a novel γ-PGA-producing strain, Bacillus halotolerans F29. The one-factor-at-a-time method was used to investigate the influence of carbon sources, nitrogen sources, and culture parameters on γ-PGA production. The optimal carbon and nitrogen sources were sucrose and (NH₄)₂SO₄, respectively. The optimal culture conditions for γ-PGA production were determined to be 37 °C and a pH of 5.5. Response surface methodology was used to determine the optimum medium components: 77.6 g/L sucrose, 43.0 g/L monosodium glutamate, and 2.2 g/L K₂HPO₄. The γ-PGA titer increased significantly from 8.5 ± 0.3 g/L to 20.7 ± 0.7 g/L when strain F29 was cultivated in the optimized medium. Furthermore, the γ-PGA titer reached 50.9 ± 1.5 g/L with a productivity of 1.33 g/L/h and a yield of 2.23 g of γ-PGA/g of L-glutamic acid with the optimized medium in fed-batch fermentation. The maximum γ-PGA titer reached 45.3 ± 1.1 g/L, with a productivity of 1.06 g/L/h when molasses was used as a carbon source. It should be noted that the γ-PGA yield in this study was the highest of all reported studies, indicating great potential for the industrial production of γ-PGA.

Mammaliicoccus sciuri's Pan-Immune System and the Dynamics of Horizontal Gene Transfer Among Staphylococcaceae: a One-Health CRISPR Tale.: Allan de Carvalho, Marcia Giambiagi-deMarval, Ciro César Rossi; J. Microbiol. 2024;62(9):775-784. Published online July 22, 2024; DOI: https://doi.org/10.1007/s12275-024-00156-7

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Abstract: Recently emancipated from the Staphylococcus genus due to genomic differences, Mammaliicoccus sciuri, previously classified as an occasional pathogen, emerges as a significant player in the landscape of resistance gene dissemination among Staphylococcaceae. Despite its classification, its role remained enigmatic. In this study, we delved into the genomic repertoire of M. sciuri to unravel its contribution to resistance and virulence gene transfer in the context of One Health. Through comprehensive analysis of publicly available genomes, we unveiled a diverse pan-immune system adept at defending against exogenous genetic elements, yet concurrently fostering horizontal gene transfer (HGT). Specifically, exploration of CRISPR-Cas systems, with spacer sequences as molecular signatures, elucidated a global dissemination pattern spanning environmental, animal, and human hosts. Notably, we identified the integration of CRISPR-Cas systems within SCCmecs (Staphylococcal Cassette Chromosome mec), harboring key genes associated with pathogenicity and resistance, especially the methicillin resistance gene mecA, suggesting a strategic adaptation to outcompete other mobile genetic elements. Our findings underscored M. sciuri's active engagement in HGT dynamics and evolutionary trajectories within Staphylococcaceae, emphasizing its central role in shaping microbial communities and highlighting the significance of understanding its implications in the One Health framework, an interdisciplinary approach that recognizes the interconnectedness of human, animal, and environmental health to address global health challenges.

Whole Genome Sequence Analysis of Brucella spp. from Human, Livestock, and Wildlife in South Africa.: Koketso Desiree Mazwi, Kgaugelo Edward Lekota, Barbara Akofo Glover, Francis Babaman Kolo, Ayesha Hassim, Jenny Rossouw, Annelize Jonker, Justnya Maria Wojno, Giuseppe Profiti, Pier Luigi Martelli, Rita Casadio, Katiuscia Zilli, Anna Janowicz, Francesca Marotta, Giuliano Garofolo, Henriette van Heerden; J. Microbiol. 2024;62(9):759-773. Published online July 22, 2024; DOI: https://doi.org/10.1007/s12275-024-00155-8

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Abstract: Brucellosis is an economically important zoonotic disease affecting humans, livestock, and wildlife health globally and especially in Africa. Brucella abortus and B. melitensis have been isolated from human, livestock (cattle and goat), and wildlife (sable) in South Africa (SA) but with little knowledge of the population genomic structure of this pathogen in SA. As whole genome sequencing can assist to differentiate and trace the origin of outbreaks of Brucella spp. strains, the whole genomes of retrospective isolates (n = 19) from previous studies were sequenced. Sequences were analysed using average nucleotide identity (ANI), pangenomics, and whole genome single nucleotide polymorphism (wgSNP) to trace the geographical origin of cases of brucellosis circulating in human, cattle, goats, and sable from different provinces in SA. Pangenomics analysis of B. melitensis (n = 69) and B. abortus (n = 56) was conducted with 19 strains that included B. abortus from cattle (n = 3) and B. melitensis from a human (n = 1), cattle (n = 1), goat (n = 1), Rev1 vaccine strain (n = 1), and sable (n = 12). Pangenomics analysis of B. melitensis genomes, highlighted shared genes, that include 10 hypothetical proteins and genes that encodes for acetyl-coenzyme A synthetase (acs), and acylamidase (aam) amongst the sable genomes. The wgSNP analysis confirmed the B. melitensis isolated from human was more closely related to the goat from the Western Cape Province from the same outbreak than the B. melitensis cattle sample from different cases in the Gauteng Province. The B. melitensis sable strains could be distinguished from the African lineage, constituting their own African sub-clade. The sequenced B. abortus strains clustered in the C2 lineage that is closely related to the isolates from Mozambique and Zimbabwe. This study identified genetically diverse Brucella spp. among various hosts in SA. This study expands the limited known knowledge regarding the presence of B. melitensis in livestock and humans in SA, further building a foundation for future research on the distribution of the Brucella spp. worldwide and its evolutionary background.

Review

Adenoviral Vector System: A Comprehensive Overview of Constructions, Therapeutic Applications and Host Responses.: Anyeseu Park, Jeong Yoon Lee; J. Microbiol. 2024;62(7):491-509. Published online July 22, 2024; DOI: https://doi.org/10.1007/s12275-024-00159-4

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1 Citations

Abstract: Adenoviral vectors are crucial for gene therapy and vaccine development, offering a platform for gene delivery into host cells. Since the discovery of adenoviruses, first-generation vectors with limited capacity have evolved to third-generation vectors flacking viral coding sequences, balancing safety and gene-carrying capacity. The applications of adenoviral vectors for gene therapy and anti-viral treatments have expanded through the use of in vitro ligation and homologous recombination, along with gene editing advancements such as CRISPR-Cas9. Current research aims to maintain the efficacy and safety of adenoviral vectors by addressing challenges such as pre-existing immunity against adenoviral vectors and developing new adenoviral vectors from rare adenovirus types and non-human species. In summary, adenoviral vectors have great potential in gene therapy and vaccine development. Through continuous research and technological advancements, these vectors are expected to lead to the development of safer and more effective treatments.

Journal Articles

Deletion of IRC19 Causes Defects in DNA Double-Strand Break Repair Pathways in Saccharomyces cerevisiae.: Ju-Hee Choi, Oyungoo Bayarmagnai, Sung-Ho Bae; J. Microbiol. 2024;62(9):749-758. Published online July 12, 2024; DOI: https://doi.org/10.1007/s12275-024-00152-x

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Abstract: DNA double-strand break (DSB) repair is a fundamental cellular process crucial for maintaining genome stability, with homologous recombination and non-homologous end joining as the primary mechanisms, and various alternative pathways such as single-strand annealing (SSA) and microhomology-mediated end joining also playing significant roles under specific conditions. IRC genes were previously identified as part of a group of genes associated with increased levels of Rad52 foci in Saccharomyces cerevisiae. In this study, we investigated the effects of IRC gene mutations on DSB repair, focusing on uncharacterized IRC10, 19, 21, 22, 23, and 24. Gene conversion (GC) assay revealed that irc10Δ, 22Δ, 23Δ, and 24Δ mutants displayed modest increases in GC frequencies, while irc19Δ and irc21Δ mutants exhibited significant reductions. Further investigation revealed that deletion mutations in URA3 were not generated in irc19Δ mutant cells following HO-induced DSBs. Additionally, irc19Δ significantly reduced frequency of SSA, and a synergistic interaction between irc19Δ and rad52Δ was observed in DSB repair via SSA. Assays to determine the choice of DSB repair pathways indicated that Irc19 is necessary for generating both GC and deletion products. Overall, these results suggest a potential role of Irc19 in DSB repair pathways, particularly in end resection process.

Cultivation of Diverse Novel Marine Bacteria from Deep Ocean Sediment Using Spent Culture Supernatant of Ca. Bathyarchaeia Enrichment.: Sidra Erum Ishaq, Tariq Ahmad, Lewen Liang, Ruize Xie, Tiantian Yu, Yinzhao Wang, Fengping Wang; J. Microbiol. 2024;62(8):611-625. Published online July 10, 2024; DOI: https://doi.org/10.1007/s12275-024-00145-w

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Abstract: Most microorganisms resist pure cultivation under conventional laboratory conditions. One of the primary issues for this un-culturability is the absence of biologically produced growth-promoting factors in traditionally defined growth media. However, whether cultivating microbes by providing spent culture supernatant of pivotal microbes in the growth medium can be an effective approach to overcome this limitation is still an under-explored area of research. Here, we used the spent culture medium (SCM) method to isolate previously uncultivated marine bacteria and compared the efficiency of this method with the traditional cultivation (TC) method. In the SCM method, Ca. Bathyarchaeia-enriched supernatant (10%) was used along with recalcitrant organic substrates such as lignin, humic acid, and organic carbon mixture. Ca. Bathyarchaeia, a ubiquitous class of archaea, have the capacity to produce metabolites, making their spent culture supernatant a key source to recover new bacterial stains. Both cultivation methods resulted in the recovery of bacterial species from the phyla Pseudomonadota, Bacteroidota, Actinomycetota, and Bacillota. However, our SCM approach also led to the recovery of species from rarely cultivated groups, such as Planctomycetota, Deinococcota, and Balneolota. In terms of the isolation of new taxa, the SCM method resulted in the cultivation of 80 potential new strains, including one at the family, 16 at the genus, and 63 at the species level, with a novelty ratio of ~ 35% (80/219). In contrast, the TC method allowed the isolation of ~ 10% (19/171) novel strains at species level only. These findings suggest that the SCM approach improved the cultivation of novel and diverse bacteria.

Enhancing Seed Germination of Cremastra appendiculata: Screening and Identification of Four New Symbiotic Fungi in the Psathyrellaceae Family.: Zhangneng Pan, Jing Wang, Shanshan He, Haiyang Zhao, Xinyue Dong, Tao Feng, Yanyan Meng, Xiaojun Li; J. Microbiol. 2024;62(8):671-682. Published online June 28, 2024; DOI: https://doi.org/10.1007/s12275-024-00148-7

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Abstract: Several coprinoid fungi have been identified as promotors of Cremastra appendiculata seed germination, while others appear ineffective. This study aimed to discern which genera within the Psathyrellaceae family exhibit this capability and to identify the most effective coprinoid fungi for the cultivation of C. appendiculata. We collected 21 coprinoid fungi from diverse sources and symbiotically cultured them with C. appendiculata seeds. 9 fungi were found to induce seed germination and support seed development, specifically within the genera Coprinellus, Tulosesus, and Candolleomyces. In contrast, fungi that failed to promote germination predominantly belonged to the genera Coprinopsis and Parasola. Notably, four fungi-Coprinellus xanthothrix, Coprinellus pseudodisseminatus, Psathyrella singeri, and Psathyrella candolleana-were documented for the first time as capable of enhancing C. appendiculata seed germination. Strain 218LXJ-10, identified as Coprinellus radians, demonstrated the most significant effect and has been implemented in large-scale production, underscoring its considerable practical value. These findings contribute vital scientific insights for the conservation and sustainable use of C. appendiculata resources.

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

Delineating the Acquired Genetic Diversity and Multidrug Resistance in Alcaligenes from Poultry Farms and Nearby Soil.: Abhilash Bhattacharjee, Anil Kumar Singh; J. Microbiol. 2024;62(7):511-523. Published online June 21, 2024; DOI: https://doi.org/10.1007/s12275-024-00129-w

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Abstract: Alcaligenes faecalis is one of the most important and clinically significant environmental pathogens, increasing in importance due to its isolation from soil and nosocomial environments. The Gram-negative soil bacterium is associated with skin endocarditis, bacteremia, dysentery, meningitis, endophthalmitis, urinary tract infections, and pneumonia in patients. With emerging antibiotic resistance in A. faecalis, it has become crucial to understand the origin of such resistance genes within this clinically significant environmental and gut bacterium. In this research, we studied the impact of antibiotic overuse in poultry and its effect on developing resistance in A. faecalis. We sampled soil and faecal materials from five poultry farms, performed whole genome sequencing & analysis and identified four strains of A. faecalis. Furthermore, we characterized the genes in the genomic islands of A. faecalis isolates. We found four multidrug-resistant A. faecalis strains that showed resistance against vancomycin (MIC >1000 μg/ml), ceftazidime (50 μg/ml), colistin (50 μg/ml) and ciprofloxacin (50 μg/ml). From whole genome comparative analysis, we found more than 180 resistance genes compared to the reference sequence. Parts of our assembled contigs were found to be similar to different bacteria which included pbp1A and pbp2 imparting resistance to amoxicillin originally a part of Helicobacter and Bordetella pertussis. We also found the Mycobacterial insertion element IS6110 in the genomic islands of all four genomes. This prominent insertion element can be transferred and induce resistance to other bacterial genomes. The results thus are crucial in understanding the transfer of resistance genes in the environment and can help in developing regimes for antibiotic use in the food and poultry industry.

RapB Regulates Cell Adhesion and Migration in Dictyostelium, Similar to RapA.: Uri Han, Nara Han, Byeonggyu Park, Taeck Joong Jeon; J. Microbiol. 2024;62(8):627-637. Published online June 17, 2024; DOI: https://doi.org/10.1007/s12275-024-00143-y

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Abstract: Ras small GTPases act as molecular switches in various cellular signaling pathways, including cell migration, proliferation, and differentiation. Three Rap proteins are present in Dictyostelium; RapA, RapB, and RapC. RapA and RapC have been reported to have opposing functions in the control of cell adhesion and migration. Here, we investigated the role of RapB, a member of the Ras GTPase subfamily in Dictyostelium, focusing on its involvement in cell adhesion, migration, and developmental processes. This study revealed that RapB, similar to RapA, played a crucial role in regulating cell morphology, adhesion, and migration. rapB null cells, which were generated by CRISPR/Cas9 gene editing, displayed altered cell size, reduced cell-substrate adhesion, and increased migration speed during chemotaxis. These phenotypes of rapB null cells were restored by the expression of RapB and RapA, but not RapC. Consistent with these results, RapB, similar to RapA, failed to rescue the phenotypes of rapC null cells, spread morphology, increased cell adhesion, and decreased migration speed during chemotaxis. Multicellular development of rapB null cells remained unaffected. These results suggest that RapB is involved in controlling cell morphology and cell adhesion. Importantly, RapB appears to play an inhibitory role in regulating the migration speed during chemotaxis, possibly by controlling cell-substrate adhesion, resembling the functions of RapA. These findings contribute to the understanding of the functional relationships among Ras subfamily proteins.

Licochalcone A Protects Vaginal Epithelial Cells Against Candida albicans Infection Via the TLR4/NF-κB Signaling Pathway.: Wei Li, Yujun Yin, Taoqiong Li, Yiqun Wang, Wenyin Shi; J. Microbiol. 2024;62(7):525-533. Published online May 31, 2024; DOI: https://doi.org/10.1007/s12275-024-00134-z

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Abstract: Vulvovaginal candidiasis (VVC) is a prevalent condition affecting a significant portion of women worldwide. Licochalcone A (LA), a natural compound with diverse biological activities, holds promise as a protective agent against Candida albicans (C. albicans) infection. This study aims to investigate the potential of LA to safeguard vaginal epithelial cells (VECs) from C. albicans infection and elucidate the underlying molecular mechanisms. To simulate VVC in vitro, VK2-E6E7 cells were infected with C. albicans. Candida albicans biofilm formation, C. albicans adhesion to VK2-E6E7 cells, and C. albicans-induced cell damage and inflammatory responses were assessed by XTT reduction assay, fluorescence assay, LDH assay, and ELISA. CCK-8 assay was performed to evaluate the cytotoxic effects of LA on VK2-E6E7 cells. Western blotting assay was performed to detect protein expression. LA dose-dependently hindered C. albicans biofilm formation and adhesion to VK2-E6E7 cells. Furthermore, LA mitigated cell damage, inhibited the Bax/Bcl-2 ratio, and attenuated the secretion of pro-inflammatory cytokines in C. albicans-induced VK2-E6E7 cells. The investigation into LA's impact on the Toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) pathway revealed that LA downregulated TLR4 expression and inhibited NF-κB activation in C. albicans-infected VK2-E6E7 cells. Furthermore, TLR4 overexpression partially abated LA-mediated protection, further highlighting the role of the TLR4/NF-κB pathway. LA holds the potential to safeguard VECs against C. albicans infection, potentially offering therapeutic avenues for VVC management.

Repeated Exposure of Vancomycin to Vancomycin-Susceptible Staphylococcus aureus (VSSA) Parent Emerged VISA and VRSA Strains with Enhanced Virulence Potentials.: An Nguyen, J Jean Sophy Roy, Ji-Hoon Kim, Kyung-Hee Yun, Wonsik Lee, Kyeong Kyu Kim, Truc Kim, Akhilesh Kumar Chaurasia; J. Microbiol. 2024;62(7):535-553. Published online May 30, 2024; DOI: https://doi.org/10.1007/s12275-024-00139-8

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Abstract: The emergence of resistance against the last-resort antibiotic vancomycin in staphylococcal infections is a serious concern for human health. Although various drug-resistant pathogens of diverse genetic backgrounds show higher virulence potential, the underlying mechanism behind this is not yet clear due to variability in their genetic dispositions. In this study, we investigated the correlation between resistance and virulence in adaptively evolved isogenic strains. The vancomycin-susceptible Staphylococcus aureus USA300 was exposed to various concentrations of vancomycin repeatedly as a mimic of the clinical regimen to obtain mutation(s)-accrued-clonally-selected (MACS) strains. The phenotypic analyses followed by expression of the representative genes responsible for virulence and resistance of MACS strains were investigated. MACS strains obtained under 2 and 8 µg/ml vancomycin, named Van2 and Van8, respectively; showed enhanced vancomycin minimal inhibitory concentrations (MIC) to 4 and 16 µg/ml, respectively. The cell adhesion and invasion of MACS strains increased in proportion to their MICs. The correlation between resistance and virulence potential was partially explained by the differential expression of genes known to be involved in both virulence and resistance in MACS strains compared to parent S. aureus USA300. Repeated treatment of vancomycin against vancomycin-susceptible S. aureus (VSSA) leads to the emergence of vancomycin-resistant strains with variable levels of enhanced virulence potentials.

Review

Reverse Zoonotic Transmission of SARS-CoV-2 and Monkeypox Virus: A Comprehensive Review.: Chiranjib Chakraborty, Manojit Bhattacharya, Md Aminul Islam, Hatem Zayed, Elijah Ige Ohimain, Sang-Soo Lee, Prosun Bhattacharya, Kuldeep Dhama; J. Microbiol. 2024;62(5):337-354. Published online May 23, 2024; DOI: https://doi.org/10.1007/s12275-024-00138-9

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Abstract: Reverse zoonosis reveals the process of transmission of a pathogen through the human-animal interface and the spillback of the zoonotic pathogen. In this article, we methodically demonstrate various aspects of reverse zoonosis, with a comprehensive discussion of SARS-CoV-2 and MPXV reverse zoonosis. First, different components of reverse zoonosis, such as humans, different pathogens, and numerous animals (poultry, livestock, pets, wild animals, and zoo animals), have been demonstrated. Second, it explains the present status of reverse zoonosis with different pathogens during previous occurrences of various outbreaks, epidemics, and pandemics. Here, we present 25 examples from literature. Third, using several examples, we comprehensively illustrate the present status of the reverse zoonosis of SARS-CoV-2 and MPXV. Here, we have provided 17 examples of SARS-CoV-2 reverse zoonosis and two examples of MPXV reverse zoonosis. Fourth, we have described two significant aspects of reverse zoonosis: understanding the fundamental aspects of spillback and awareness. These two aspects are required to prevent reverse zoonosis from the current infection with two significant viruses. Finally, the One Health approach was discussed vividly, where we urge scientists from different areas to work collaboratively to solve the issue of reverse zoonosis.

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.

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.

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