• Genomics & Informatics
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• 제11권4호
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• pp.272-276
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• 2013

Sequence analysis of the 16S rRNA gene has been widely used for the classification of microorganisms. However, we have been unable to clearly identify five Flavobacterium species isolated from a freshwater by using the gene as a single marker, because the evolutionary history is incomplete and the pace of DNA substitutions is relatively rapid in the bacteria. In this study, we tried to classify Flavobacterium species through multilocus sequence analysis (MLSA), which is a practical and reliable technique for the identification or classification of bacteria. The five Flavobacterium species isolated from freshwater and 37 other strains were classified based on six housekeeping genes: gyrB, dnaK, tuf, murG, atpA, and glyA. The genes were amplified by PCR and subjected to DNA sequencing. Based on the combined DNA sequence (4,412 bp) of the six housekeeping genes, we analyzed the phylogenetic relationship among the Flavobacterium species. The results indicated that MLSA, based on the six housekeeping genes, is a trustworthy method for the identification of closely related Flavobacterium species.

• 한국어병학회지
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• 제22권3호
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• pp.391-400
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• 2009

Genetic identification of 17 fish-derived Aeromonas strains was attempted using 5 housekeeping genes. 16S rRNA, gyrB, rpoD, dnaJ and recA genes from the 17 strains were amplified, and total of 85 amplicons were sequenced. DNA sequences of the strains and type strains of the 17 Aeromonas homology groups were used for genetic identification and phylogenetic analyses. None of the strains was identified as a single species using the 16S rRNA gene, showing the same identities (average = 99.7%) with several Aeromonas species. According to gyrB, rpoD, dnaJ, and recA, 9 strains and RFAS-1 used in this study were identified as A. hydrophila and A. salmonicida, respectively. However, the other strains were closely related to 2 or more Aeromonas species (i.e., A. salmonicida, A. veronii, A. jandaei, A. media and A. troda) depending on the genetic marker used. In this study, gyrB, rpoD, dnaJ and recA gene sequences proved to be advantageous over 16S rRNA for the identification of field Aeromonas isolates obtained from fish. However, there are discrepancies between analyses of different phylogenetic markers, indicating there are still difficulties in genetic identification of the genus Aeromonas using the housekeeping genes used in this study. Advantages and disadvantages of each housekeeping gene should be taken into account when the gene is used for identification of Aeromonas species.

• Journal of Microbiology and Biotechnology
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• 제33권8호
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• pp.1084-1090
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• 2023

The strain KIST612, initially identified as E. limosum, was a suspected member of E. callanderi due to differences in phenotype, genotype, and average nucleotide identity (ANI). Here, we found that E. limosum ATCC 8486^T and KIST612 are genetically different in their central metabolic pathways, such as that of carbon metabolism. Although 16S rDNA sequencing of KIST612 revealed high identity with E. limosum ATCC 8486^T (99.2%) and E. callanderi DSM 3662^T (99.8%), phylogenetic analysis of housekeeping genes and genome metrics clearly indicated that KIST612 belongs to E. callanderi. The phylogenies showed that KIST612 is closer to E. callanderi DSM 3662^T than to E. limosum ATCC 8486^T. The ANI between KIST612 and E. callanderi DSM 3662^T was 99.8%, which was above the species cut-off of 96%, Meanwhile, the ANI value with E. limosum ATCC 8486^T was not significant, showing only 94.6%. The digital DNA-DNA hybridization (dDDH) results also supported the ANI values. The dDDH between KIST612 and E. callanderi DSM 3662^T was 98.4%, whereas between KIST612 and E. limosum ATCC 8486^T , it was 57.8%, which is lower than the species cut-off of 70%. Based on these findings, we propose the reclassification of E. limosum KIST612 as E. callanderi KIST612.

• Clinical and Experimental Pediatrics
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• 제58권1호
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• pp.20-27
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• 2015

Purpose: We investigated the molecular types of uropathogenic Escherichia coli (UPEC) by using conventional phylogrouping, multilocus sequence typing (MLST), and fimH genotyping. Methods: Samples of patients younger than 18 years of age were collected from the Chung-Ang University Hospital over 2 years. Conventional phylogenetic grouping for UPEC strains was performed by polymerase chain reaction (PCR). Bacterial strain sequence types (STs) were classified on the basis of the results of partial sequencing of seven housekeeping genes. In addition, we analyzed nucleotide variations in a 424-base pair fragment of fimH, a major virulence factor in UPEC. Results: Sixty-four UPEC isolates were analyzed in this study. Phylogenetic grouping revealed that group B2 was the most common type (n=54, 84%). We identified 16 distinctive STs using MLST. The most common STs were ST95 (35.9%), ST73 (15.6%), ST131 (12.5%), ST69 (7.8%), and ST14 (6.3%). Fourteen fimH allele types were identified, of which 11 had been previously reported, and the remaining three were identified in this study. f1 (n=28, 45.2%) was found to be the most common allele type, followed by f6 and f9 (n=7, 11.3% each). Comparative analysis of the results from the three different molecular typing techniques revealed that both MLST and fimH typing generated more discriminatory UPEC types than did PCR-based phylogrouping. Conclusion: We characterized UPEC molecular types isolated from Korean children by MLST and fimH genotyping. fimH genotyping might serve as a useful molecular test for large epidemiologic studies of UPEC isolates.

• 한국어류학회지
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• 제18권4호
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• pp.293-299
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• 2006

두툽상어 (Scyliorhinus torazame)부터 분리된 항산화 효소 Cu,Zn-superoxide dismutase (Cu,Zn-SOD 또는 SOD1)의 핵산 염기서열 및 추정 아미노산 서열을 대상으로 분자 계통학적 분석을 실시하였다. 종래 알려져 있는 척추동물의 Cu,Zn-SOD 서열들을 포함하여 neighbor-joining (NJ), maximum parsimony (MP), maximum likelihood (ML) 및 Bayesian 분석 등을 포함한 다양한 계통 분석을 수행하였으며, 이를 통해 연골어류인 본 어종의 척추동물 분류군 내에서의 계통적 위치를 추정하고자 하였다. 다양한 분자 계통수로부터 얻어진 대부분의 consensus tree들에서 분석에 사용한 분류군들은 종래 알려진 분류학적 위치와 비교적 잘 일치하였고, 이중 두툽상어는 같은 연골어류종인 blue shark와 높은 유연관계를 나타내면서 보다 진화한 경골어류들과는 확연히 구분되는 분지를 형성하였다. 특히 핵산 염기서열을 바탕으로 한 neighbor-joining 분석에서 두툽상어는 경골어류와 양막동물에 비해 보다 원시형태의 척추동물 Cu,Zn-SOD 유전자의 한 형태를 보유하고 있는 것으로 나타났다.