Journal of Microbiology

Journal Articles

Characterization and Comparative Genomic Analysis of vB_BceM_CEP1: A Novel Temperate Bacteriophage Infecting Burkholderia cepacia Complex.: Momen Askoura, Eslam K Fahmy, Safya E Esmaeel, Wael A H Hegazy, Aliaa Abdelghafar; J. Microbiol. 2024;62(11):1035-1055. Published online November 18, 2024; DOI: https://doi.org/10.1007/s12275-024-00185-2

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Abstract: The increasing prevalence of multidrug-resistant bacteria imminently threatens public health and jeopardizes nearly all aspects of modern medicine. The Burkholderia cepacia complex (Bcc) comprises Burkholderia cepacia and the related species of Gram-negative bacteria. Members of the Bcc group are opportunistic pathogens responsible for various chronic illnesses, including cystic fibrosis and chronic granulomatous disease. Phage therapy is emerging as a potential solution to combat the antimicrobial resistance crisis. In this study, a temperate phage vB_BceM_CEP1 was isolated from sewage and fully characterized. Transmission electron microscopy indicated that vB_BceM_CEP1 belongs to the family Peduoviridae. The isolated phage demonstrated enhanced environmental stability and antibiofilm potential. One-step growth analysis revealed a latent period of 30 min and an average burst size of 139 plaque-forming units per cell. The genome of vB_BceM_CEP1 consists of 32,486 bp with a GC content of 62.05%. A total of 40 open reading frames were annotated in the phage genome, and none of the predicted genes was annotated as tRNA. Notably, genes associated with antibiotic resistance, host virulence factors, and toxins were absent from the vB_BceM_CEP1 genome. Based on its unique phenotype and phylogeny, the isolated phage vB_BceM_CEP1 is classified as a new temperate phage with lytic activity. The findings of this study enhance our understanding of the diversity of Bcc phages.

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.

Cytophaga hutchinsonii chu_2177, encoding the O-antigen ligase, is essential for cellulose degradation: Yahong Tan , Wenxia Song , Lijuan Gao , Weican Zhang , Xuemei Lu; J. Microbiol. 2022;60(4):364-374. Published online January 7, 2022; DOI: https://doi.org/10.1007/s12275-022-1531-3

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Abstract: Cytophaga hutchinsonii can efficiently degrade crystalline cellulose, in which the cell surface cellulases secreted by the type IX secretion system (T9SS) play important roles, but the degradation mechanism remains unclear, and the anchor mechanism of cellulases on the outer membrane in C. hutchinsonii has not been studied. Here, chu_2177 was identified by transposon mutagenesis and was proved to be indispensable for cellulose utilization in C. hutchinsonii. Disruption of chu_2177 resulted in O-antigen deficiency and chu_ 177 could confer O-antigen ligase activity upon an Escherichia coli waal mutant, indicating that chu_2177 encoded the Ontigen ligase. Moreover, deletion of chu_2177 caused defects in cellulose utilization, cell motility, biofilm formation, and stress resistance. Further study showed that the endoglucanase activity was markedly decreased in the outer membrane but was increased in the culture fluid without chu_2177. Western blot proved that endoglucanase CHU_1336 was not located on the outer membrane but was released in the culture fluid of the Δ2177 mutant. Further proteomics analysis showed that many cargo proteins of T9SS were missing in the outer membrane of the Δ2177 mutant. Our study revealed that the deletion of chu_2177 affected the localization of many T9SS cargo proteins including cellulases on the outer membrane of C. hutchinsonii.

Salmonella Typhimurium ST313 isolated in Brazil revealed to be more invasive and inflammatory in murine colon compared to ST19 strains: Amanda Aparecida Seribelli , Tamara R. Machado Ribeiro , Patrick da Silva† , Isabela Mancini Martins , Felipe Pinheiro Vilela , Marta I. Cazentini Medeiros , Kamila Chagas Peronni , Wilson Araújo da Silva Junior , Cristiano Gallina Moreira , Juliana Pfrimer Falcão; J. Microbiol. 2021;59(9):861-870. Published online August 12, 2021; DOI: https://doi.org/10.1007/s12275-021-1082-z

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5 Citations

Abstract: Salmonella Typhimurium (ST313) has caused an epidemic of invasive disease in sub-Saharan Africa and has been recently identified in Brazil. As the virulence of this ST is poorly understood, the present study aimed to (i) perform the RNAseq in vitro of S. Typhimurium STm30 (ST313) grown in Luria-Bertani medium at 37°C; (ii) compare it with the RNAseq of the S. Typhimurium SL1344 (ST19) and S. Typhimurium STm11 (ST19) strains under the same growing conditions; and (iii) examine the colonization capacity and expression of virulence genes and cytokines in murine colon. The STm30 (ST313) strain exhibited stronger virulence and was associated with a more inflammatory profile than the strains SL1344 (ST19) and STm11 (ST19), as demonstrated by transcriptome and in vivo assay. The expression levels of the hilA, sopD2, pipB, and ssaS virulence genes, other Salmonella pathogenicity islands SPI-1 and SPI-2 genes or effectors, and genes of the cytokines IL-1β, IFN-γ, TNF-α, IL-6, IL-17, IL-22, and IL-12 were increased during ST313 infection in C57BL/6J mice. In conclusion, S. Typhimurium STm30 (ST313) isolated from human feces in Brazil express higher levels of pathogenesis- related genes at 37°C and has stronger colonization and invasion capacity in murine colon due to its high expression levels of virulence genes, when compared with the S. Typhimurium SL1344 (ST19) and STm11 (ST19) strains. STm30 (ST313) also induces stronger expression of pro-inflammatory cytokines in this organ, suggesting that it causes more extensive tissue damage.

Sequence analysis of the first B5 subgenogroup strain of enterovirus 71 isolated in Korea: Yu Jung Won , Lae Hyung Kang , Ah Ra Lee , Bomina Paik , Hyun Kim , Sung Geun Lee , Seung Won Park , Seung Jin Hong , Soon Young Paik; J. Microbiol. 2020;58(5):422-429. Published online March 28, 2020; DOI: https://doi.org/10.1007/s12275-020-9539-z

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Abstract: Enterovirus A71 (EV71), the main etiological agent of handfoot- mouth disease (HFMD), circulates in many areas of the world and has caused large epidemics since 1997, especially in the Asia-Pacific region. In this study, we determined the full-genome sequence of CMC718, a newly isolated EV71 strain in Korea. The CMC718 genome was 7,415 nucleotides in length and was confirmed by whole-genome phylogenetic analysis to belong to the B5 genotype. In particular, CMC718 demonstrated maximum identity with strain M988 of the B5 genotype and numerous amino acid variants were detected in the 3D domain of the viral protein P3, which is consistent with the mutation pattern of a B5 strain isolated in 2012–2013. Comparison of the CMC718 sequence with other EV71 reference strains confirmed the relationship and genetic variation of CMC718. Our study was a full-genome sequence analysis of the first EV71 strain of the B5 genotype isolated in South Korea. This information will be a valuable reference for the development of methods for the detection of recombinant viruses, the tracking of infections, and the diagnosis of EV71.

Hahyoungchilella caricis gen. nov., sp. nov., isolated from a rhizosphere mudflat of a halophyte (Carex scabrifolia), transfer of Thioclava arenosa Thongphrom et al. 2017 to Pseudothioclava as Pseudothioclava arenosa gen. nov., comb. nov. and proposal of Thioclava electrotropha Chang et al. 2018: Young-Ju Kim , Soon Dong Lee; J. Microbiol. 2019;57(12):1048-1055. Published online September 25, 2019; DOI: https://doi.org/10.1007/s12275-019-9260-y

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Abstract: A Gram-stain-negative, strictly aerobic, marine bacterium, designated GH2-2T, was isolated from a rhizosphere mudflat of a halophyte (Carex scabrifolia) in Gangwha Island, the Republic of Korea. The cells of the organism were oxidase- positive, catalase-positive, flagellated, short rods that grew at 10–40°C, pH 4–10, and 0–13% (w/v) NaCl. The predominant ubiquinone was Q-10. The major polar lipids were phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol. The major fatty acid is C18:1. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the novel isolate formed an independent lineage at the base of the radiation encompassing members of the genus Thioclava, except for Thioclava arenosa. The closest relatives were T. nitratireducens (96.03% sequence similarity) and T. dalianensis (95.97%). The genome size and DNA G+C content were 3.77 Mbp and 59.6 mol%, respectively. Phylogenomic analysis supported phylogenetic distinctness based on 16S rRNA gene sequences. Average nucleotide identity values were 73.6–74.0% between the novel strain and members of the genus Thioclava. On the basis of data obtained from a polyphasic approach, the strain GH2-2T (= KCTC 62124T = DSM 105743T) represents a novel species of a new genus for which the name Hahyoungchilella caricis gen. nov., sp. nov. is proposed. Moreover, the transfer of Thioclava arenosa Thongphrom et al. 2017 to Pseudothioclava gen. nov. as Pseudothioclava arenosa comb. nov. is also proposed. Finally, Thioclava electrotropha Chang et al. 2018 is proposed to be a later heterosynonym of Thioclava sediminum Liu et al. 2017.

Molecular genomic characterization of severe fever with thrombocytopenia syndrome virus isolates from South Korea: Yu Jung Won , Lae Hyung Kang , Sung Geun Lee , Seung Won Park , Jae Ik Han , Soon Young Paik; J. Microbiol. 2019;57(10):927-937. Published online August 3, 2019; DOI: https://doi.org/10.1007/s12275-019-9174-8

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Abstract: Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne emerging infectious disease caused by the SFTS virus (SFTSV) and is a threat to public health due to its high fatality rate. However, details on tick-to-human transmission of SFTSV are limited. In this study, we determined the wholegenome sequence of a South Korean SFTSV strain (CUKJJ01), compared it to those of other recent human SFTSV isolates, and identified the genetic variations and relationships among the SFTSV strains. The genome of CUK-JJ01 was consistent with the genome of other members of the genus Phlebovirus, including the large (L), medium (M), and small (S) segments of 6368, 3378, and 1744 nucleotides, respectively. Based on amino acid sequences of the M and S segments, which are used to distinguish the six SFTSV genotypes, CUK-JJ01 was classified as genotype B. Segment analysis revealed that the L, M, and S segments were 97.49%, 97.18%, and 97.94% similar to those of KAJNH2/2013/ Korea, ZJZHSH-FDE/2012/China, and KADGH/2013/Korea, respectively. Currently, only few studies on SFTSV have been conducted in Korean population and most were limited to serological analysis. Although the present study has limitations in terms of number of sample analyzed, the findings may serve as basis to understand the transmission and spread of SFTSV, as well as for the development of diagnostic and detection methods for viral recombinants by comparing the whole genome sequence of SFTSV isolates from South Korea and that of foreign isolates.

Gramella fulva sp. nov., isolated from a dry surface of tidal flat: Sae Hyun Hwang , Woon Mo Hwang , Keunsoo Kang , Tae-Young Ahn; J. Microbiol. 2019;57(1):23-29. Published online November 19, 2018; DOI: https://doi.org/10.1007/s12275-019-8370-x

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9 Citations

Abstract: A novel Gram-stain-negative, aerobic, motile by means of gliding, and short rod-shaped bacterium, designated strain SH35T, was isolated from the dry surface of a tidal flat in Hwasung-si, South Korea. Growth occurred at 10–40°C (optimum 30°C), at pH 6.0–8.0 (optimum pH 7.0), in 1–12% NaCl (optimum 2%), and was inhibited in the absence of NaCl and Ca2+ ions. Phylogenetic analysis based on the 16S rRNA gene sequences showed that strain SH35T belonged to the genus Gramella and was a member of the family Flavobacteriaceae with highest sequence similarity to Gramella flava JLT2011T (96.1%), followed by Gramella oceani CCAMSZ- TT (95.6%), and 93.0–94.9% to other recognized Gramella species. The major cellular fatty acids (> 5% of the total) of strain SH35T were iso-C15:0, Iso-C16:0, anteiso-C15:0, iso-C17:0 3-OH and summed feature 9 (C16:0 10-methyl and/or C17:1 iso ω9с). The major polar lipids were phosphatidylethanolamine, two unidentified aminolipids and nine unidentified polar lipids. The major respiratory quinone and the predominant polyamine were menaquinone-6 (MK-6) and symhomospermidine, respectively. The DNA G + C content was 40.5 mol% (39.7% based on total genome calculations). Based on phylogenetic analysis and physiological and biochemical characterization, strain SH35T represents a novel species of the genus Gramella, for which the name Gramella fulva sp. nov. is proposed. The type strain is SH35T (= KACC 19447T = JCM 32369T).

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