• 한국미생물·생명공학회지
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• 제51권3호
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• pp.309-313
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• 2023

Here we report essential features of the draft genome of an AmpC-β-lactamase-producing bacterial isolate obtained from farm tomatoes in South Africa. The isolate designated strain Tom1 featured a genome of 4950426 bp with a G+C% of 59.83. It was identified as Serratia marcescens by ribosomal multilocus sequence typing (rMLST), digital DNA-DNA hybridization (dDDH), average nucleotide identity (ANI), and phylogenetic analysis using reference genomes. Its genome encoded an AmpC-β-lactamase (bla_SST-1), an efflux pump providing tetracycline resistance (tet(41)), and an aminoglycoside acetyltransferase (aac(6')-Ic). Additionally, genes encoding proteins involved in prodigiosin biosynthesis and associated with adherence, biofilm formation, virulence, and pathogenicity were detected.

• 한국균학회지
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• 제52권2호
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• pp.109-114
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• 2024

Anthracnose fruit rot (AFR) has been observed in greenhouses during the harvesting period in the Chungnam Province of South Korea. Fruits infected inside the greenhouse show black or brown spots, orange conidial masses and in some areas of the infected parts, white fungal growths are visible. The size of these spots gradually expands, leading to the necrosis of the fruits and flowers. Three isolates were obtained from infected fruits and identified as strains of the Colletotrichum acutatum species complex based on morphological characteristics. Multilocus sequence analysis of actin, chitin synthase, glyceraldehyde-3-phosphate dehydrogenase genes, and internal transcribed spacer rDNA regions revealed that the isolates belong to a monophyletic group with the type strain of C. nymphaeae. This is the first time C. nymphaeae has been confirmed in strawberry fruit in Korea.

• 한국균학회지
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• 제50권3호
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• pp.235-241
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• 2022

Anthracnose crown rot (ACR) has been observed in greenhouses during the nursery and harvest seasons in Gangwon Province, Korea. Infected plants showed black leaf spot, dark sunken pink conidial masses on petioles, wilting, and eventually death. Five isolates were obtained from the lesions of strawberry plants and were identified as a Colletotrichum gloeosporioides species complex based on their cultural and morphological characteristics. Multilocus sequence analysis of actin, calmodulin, chitin synthase, glyceraldehyde-3-phophate dehydrogenase genes, and internal transcribed spacer rDNA regions showed that the isolates formed a monophyletic group with the type strain of C. siamense. Pathogenicity tests were performed on the isolate, and Koch's postulates were performed to verify the relationship between Colletotrichum sp. and the strawberry plant variety Seolhyang. The isolate was pathogenic to strawberry plants, which exhibited typical ACR symptoms. Based on morphological characteristics, pathogenicity, and DNA sequence analyses, the fungus isolated in Korea was identified as C. siamense. This is first time C. siamense has been confirmed in ever-bearing strawberry varieties in Korea.

• Journal of Microbiology and Biotechnology
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• 제25권9호
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• pp.1410-1416
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• 2015

Wolbachia is an obligate symbiotic bacteria that is ubiquitous in arthropods, with 25-70% of insect species estimated to be infected. Wolbachia species can interact with their insect hosts in a mutualistic or parasitic manner. Sequence types (ST) of Wolbachia are determined by multilocus sequence typing (MLST) of housekeeping genes. However, there are some limitations to MLST with respect to the generation of clone libraries and the Sanger sequencing method when a host is infected with multiple STs of Wolbachia. To assess the feasibility of massive parallel sequencing, also known as next-generation sequencing, we used pyrosequencing for sequence typing of Wolbachia in butterflies. We collected three species of butterflies (Eurema hecabe, Eurema laeta, and Tongeia fischeri) common to Korea and screened them for Wolbachia STs. We found that T. fischeri was infected with a single ST of Wolbachia, ST41. In contrast, E. hecabe and E. laeta were each infected with two STs of Wolbachia, ST41 and ST40. Our results clearly demonstrate that pyrosequencing-based MLST has a higher sensitivity than cloning and Sanger sequencing methods for the detection of minor alleles. Considering the high prevalence of infection with multiple Wolbachia STs, next-generation sequencing with improved analysis would assist with scaling up approaches to Wolbachia MLST.

• Journal of Microbiology and Biotechnology
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• 제26권9호
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• pp.1643-1649
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• 2016

The aims of this study were to characterize the molecular epidemiological profiles of CTX-M-producing uropathogenic Escherichia coli isolates from a tertiary hospital in Daejeon, Korea, and to investigate the genetic diversity and compare the prevalence of sequence types (STs) in different areas. Extended spectrum β-lactamase-producing E. coli strains isolated from urine were analyzed for CTX-M, integrons, and insertion sequence common regions (ISCRs) by PCR and sequencing. Multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), phylogenetic analysis, and rep-PCR were also used for molecular typing of the isolates. Of 80 CTX-M producers, 31 and 46 expressed CTX-M-15 and CTX-M-14, respectively. MLST analysis indicated that the most prevalent ST was ST131 (n = 34, 42.5%), followed by ST38 (n = 22, 27.5%), ST405 (n = 8, 10.0%), and ST69 (n = 6, 7.5%). Most CTX-M producers harbored class 1 integrons. ST131 strains belonged to phylogenetic group B2 and showed identical rep-PCR patterns, whereas ST69, ST38, and ST405 strains belonged to phylogenetic group D; the ST38 and ST405 strains displayed the same rep-PCR pattern, respectively. ST131 and ST38 isolates showed 21 and 19 distinct types, respectively, by PFGE. In Daejeon, D-ST38 CTX-M-14 producers were relatively more prevalent than in other countries and Korean cities. Our results indicate that CTX-M-producing E. coli isolates belonged mostly to ST131 or ST38 and were more related to hospital-onset than to community-onset infections and that the bla_CTX-M gene may vary according to the ST.

• The Plant Pathology Journal
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• 제30권1호
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• pp.10-24
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• 2014

Genetic diversity and differentiation of 50 Colletotrichum spp. isolates from legume crops studied through multigene loci, RAPD and ISSR analysis. DNA sequence comparisons by six genes (ITS, ACT, Tub2, CHS-1, GAPDH, and HIS3) verified species identity of C. truncatum, C. dematium and C. gloeosporiodes and identity C. capsici as a synonym of C. truncatum. Based on the matrix distance analysis of multigene sequences, the Colletotrichum species showed diverse degrees of intera and interspecific divergence (0.0 to 1.4%) and (15.5-19.9), respectively. A multilocus molecular phylogenetic analysis clustered Colletotrichum spp. isolates into 3 well-defined clades, representing three distinct species; C. truncatum, C. dematium and C. gloeosporioides. The ISSR and RAPD and cluster analysis exhibited a high degree of variability among different isolates and permitted the grouping of isolates of Colletotrichum spp. into three distinct clusters. Distinct populations of Colletotrichum spp. isolates were genetically in accordance with host specificity and inconsistent with geographical origins. The large population of C. truncatum showed greater amounts of genetic diversity than smaller populations of C. dematium and C. gloeosporioides species. Results of ISSR and RAPD markers were congruent, but the effective maker ratio and the number of private alleles were greater in ISSR markers.

• 한국어병학회지
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• 제33권2호
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• pp.127-138
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• 2020

코끼리조개 성패 및 유생으로부터 잠재적 병원성 세균 분리 및 동정을 수행하였다. 분리된 균주는 분자생물학적 기법 및 생화학적 검사를 통해 동정하였으며, 명확한 동정 및 계통수 분석을 위해 16S rDNA와 하우스키핑 유전자 (pyrH, recA, rpoA)를 결합하여 분석하는 MLSA를 적용하였다. 총 141개의 균주가 분리되었으며, 건강한 성패에서는 10개, 수포 병변을 보이는 빈사 상태의 성패에서 52개, 유생에서 79개가 분리되었다. 이 중 빈사상태의 성패에서 46개, 유생에서 39개의 균주가 Vibrio 속 세균으로 동정되었으며, 나머지 균주들은 모두 일반해양세균으로 동정되었다. Vibrio 속 세균 중에서는 수포 병변을 보이는 성패에서 Vibrio splendidus가 가장 많이 분리되었으며 기존의 V. splendidus와 함께 동일한 클러스터를 형성하였다. 하지만, 인위감염실험을 실시하지 않았고 건강한 유생에서도 V. splendidus가 분리되어 성패에서 나타난 수포와 V. splendidus와의 관계는 확실하지 않으며, 차후 추가 연구가 필요할 것으로 생각된다.

• The Plant Pathology Journal
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• 제26권3호
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• pp.223-230
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• 2010

The Burkholderia cepacia complex isolates causing bacterial fruit rot of apricot were characterized by speciesspecific PCR tests, recA-HaeIII restriction fragment length polymorphism (RFLP) assays, rep-PCR genomic fingerprinting, recA gene sequencing, and multilocus sequence typing (MLST) analysis. Results indicated that the isolates Bca 0901 and Bca 0902 gave positive amplifications with primers specific for B. vietnamiensis while the two bacterial isolates showed different recA-RFLP and rep-PCR profiles from those of B. vietnamiensis strains. In addition, the two bacterial isolates had a higher proteolytic activity compared with that of the non-pathogenic B. vietnamiensis strains while no cblA and esmR marker genes were detected for the two bacterial isolates and B. vietnamiensis strains. The two bacterial isolates were identified as Burkholderia seminalis based on recA gene sequence analysis and MLST analysis. Overall, this is the first characterization of B. seminalis that cause bacterial fruit rot of apricot.

• 한국미생물·생명공학회지
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• 제48권3호
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• pp.389-398
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• 2020

The prevalence of carbapenem-resistant Enterobacteriaceae (CRE) is increasing globally, resulting in high mortality rates. Although CRE is a relatively recent problem in Korea (the first case was not diagnosed until 2010), it is responsible for serious morbidities at an alarming rate. In this study, we carried out a molecular genetic analysis to determine the incidence of CRE and carbapenemase-producing Enterobacteriaceae (CPE) at a general hospital in Korea between August 2017 and August 2019. Forty strains of CPE were isolated from various clinical specimens and analyzed via antimicrobial susceptibility testing, polymerase chain reaction to detect β-lactamase genes, deoxyribonucleic acid sequencing, multilocus sequence typing, curing testing, and conjugal transfer of plasmids. The results demonstrated that all 40 isolates were multidrug-resistant. The fluoroquinolone susceptibility test showed that 75% of the Enterobacteriaceae isolates were resistant to ciprofloxacin, whereas 72.5% were resistant to trimethoprim-sulfamethoxazole. Further, conjugation accounted for 57.5% of all resistant plasmid transfer events, which is 4.3-fold higher than that observed in 2010 by Frost et al. Finally, the high detection rate of transposon Tn4401 was associated with the rapid diffusion and evolution of CPE. Our results highlight the rapid emergence of extensively drugresistant strains in Korea and emphasize the need for employing urgent control measures and protocols at the national level.

• 식물병연구
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• 제29권1호
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• pp.64-71
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• 2023

In October 2021, soft rot disease seriously affected radish crop in Dangjin, Chungcheongnam-do, Korea. The infected radishes were stunted and turned dark green, with yellowish leaf foliage. A slimy, wet, and decayed pith region was observed in the infected roots. The bacterial strain KNUB-03-21 was isolated from infected roots. The biochemical and morphological characteristics of the isolate were similar to those of Pectobacterium brasiliense. Phylogenetic analysis based on the sequences of the 16S rRNA region and the concatenated DNA polymerase III subunit tau (dnaX), leucine-tRNA ligase (leuS), and recombinase subunit A (recA) genes confirmed that the isolate is a novel strain of P. brasiliense. Artificial inoculation of radish with P. brasiliense KNUB-03-21 resulted in soft rot symptoms similar to those observed in infected radish in the field; subsequently, P. brasiliense KNUB-03-21 was reisolated and reidentified. To our knowledge, this is the first report of P. brasiliense as a causal pathogen of radish soft rot in Korea.