• Journal of Microbiology
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• v.40 no.3
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• pp.237-240
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• 2002

A carboxydotrophic bacterium, isolated from a soil sample in Seoul, was classified initially as Acinetobacter sp. strain JC1 DSM 3803. Chemotaxanomic properties, analysis of the 16s rDNA sequence, fatty acid content, and molecular Phylogenetic analysis based on rpoB gene, however, suggested that this bacterium belongs to the genus, Mycobacterium. On the basis of this evidence, it is proposed that Acinetobacter sp. strain JC1 DSM 3803 be reclassified as Mycobacterium sp. strain JC1 DSM 3803.

• Journal of Microbiology
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• v.43 no.5
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• pp.443-450
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• 2005

The multi-host pathogen, Pseudomonas aeruginosa, possesses an extraordinary versatility which makes it capable of surviving the adverse conditions provided by environmental, host, and, presumably, competing microbial factors in its natural habitats. Here, we investigated the P. aeruginosa-Bacillus subtilis interaction in laboratory conditions and found that some P. aeruginosa strains can outcompete B. subtilis in mixed planktonic cultures. This is accompanied by the loss of B. subtilis viability. The bactericidal activity of P. aeruginosa is measured on B. subtilis plate cultures. The bactericidal activity is attenuated in pqsA, mvfR, lasR, pilB, gacA, dsbA, rpoS, and phnAB mutants. These results suggest that P. aeruginosa utilizes a subset of conserved virulence pathways in order to survive the conditions provided by its bacterial neighbors.

• Korean Journal of Veterinary Service
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• v.39 no.1
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• pp.1-6
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• 2016

In this study, Bacillus licheniformis which has been used as probiotics was isolated from Korean traditional fermented soybean. A total of 69 strains were presumptively identified as B. licheniformis by phenotypic methods. Based on PCR amplification and 16S rRNA gene sequencing, the multilocus sequence typing of gyrA and rpoB, followed by phylogenetic analysis was performed. The isolates were distinctly differentiated and found to be closely related to B. amyloliquefaciens, B. subtilis, and B. aerius. The partial 16S rRNA gene sequences of those strains matched those of B. sonorensis (97%) and B. aerius (98%) in the phylogenetic tree. In contrast, multilocus phylogenetic analysis (MLPA) showed that only 61 (86.9%) out of 69 strains were B. licheniformis. The rest of those strains were found to be B. subtilis (5.8%), B. amyloliquefaciens (2.9%), and B. sonorensis (2.9%), respectively. Therefore, our results suggested that since the 16S rRNA gene sequencing alone was not sufficient to compare and discriminate closely related lineages of Bacillus spp., it was required to analyze the MLPA simultaneously to avoid any misleading phenotype-based grouping of these closely related species.

• Research in Plant Disease
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• v.27 no.4
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• pp.180-186
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• 2021

Typical bacterial symptoms, water-soaking brown and black leaf spots with yellow halo, were observed on watermelon seedlings in nursery and field of Gyeongnam and Jeonnam provinces. Bacterial isolates from the lesion showed strong pathogenicity on watermelon and zucchini. One of them was rod-shaped with 4 polar flagella by observation of transmission electron microscopy. They belonged to LOPAT group 1. The phylogenical trees with nucleotide sequences of 16S rRNA and multi-locus sequencing typing with the 4 house-keeping genes (gapA, gltA, gyrB, and rpoD) of the isolates showed they were highly homologous to Pseudomonas syringae pv. syringae and grouped together with them, indicating that they were appeared as P. syringae genomospecies group 1. Morphological, physiological, and genetical characteristics of the isolates suggested they are P. syringae pv. syringae. We believe this is the first report that P. syringae pv. syringae caused leaf spot disease on watermelon in the Republic of Korea.

• Research in Plant Disease
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• v.29 no.4
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• pp.440-444
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• 2023

In August 2021, water-soaking symptoms of bacterial spot disease were observed on castor bean in a field in Gangseo District, Busan. Bacteria isolated from the lesion when cultured on tryptic soy agar appeared to be nonmucoid and pale green. To confirm whether the isolates were the causative agent of the spot disease, they were inoculated onto healthy castor bean plants. The same symptoms were observed on the inoculated tissue, and the bacteria were reisolated from the lesion. Furthermore, the isolates were consistent with the biochemical and physiological features of Pseudomonas capsici. Sequencing analysis using 16S rRNA and housekeeping genes (gyrB, rpoD) showed that the isolates shared a high sequence similarity with P. capsici. These results confirmed that the strains belonged to P. capsici. To our knowledge, this is the first report of bacterial spot disease caused by P. capsici on castor bean in Korea.

• Research in Plant Disease
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• v.24 no.2
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• pp.138-144
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• 2018

In December 2016, stem rot symptoms were observed on Persian buttercup (Ranunculus asiaticus) plants in Chilgok, Gyeongbuk, Korea. In the early stage of the disease, several black spots appeared on the stem of infected plants. As the disease progressed, the infected stem cleaved and wilted. The causal agent was isolated from a lesion and incubated on Reasoner's 2A (R2A) agar at $25^{\circ}C$. Total genomic DNA was extracted for phylogenetic analysis. Based on the 16S rRNA gene analysis, the isolated strain was found to belong to the genus Pseudomonas. To identify the isolated bacterial strain at the species level, the nucleotide sequences of the gyrase B (gyrB) and RNA polymerase D (rpoD) genes were obtained and compared with the sequences in the GenBank database. As the result, the causal agent of the stem rot disease was identified as Pseudomonas marginalis. To determine the pathogenicity of the isolated bacterial strain, it was inoculated into the stem of healthy R. asiaticus plant, the inoculated plant showed a lesion with the same characteristics as the naturally infected plant. Based on these results, this is the first report of bacterial stem rot on R. asiaticus caused by P. marginalis in Korea.

• Journal of Life Science
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• v.8 no.2
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• pp.216-225
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• 1998

Metal ion-induced and it’s regulatory genes were screened in virulent salmonella typhimurium UK1 and tested cross-regulation with various stresses. Using the techniqud of P22-MudJ(Km, lacZ)-directed lacZ operon fusion, LF40 cuiA::MudJ and Lf153 cuiD::MudJ which were induced by copper were selected. cuia and cuiD were determined anaerobic coper inducible and copper tolerance response gene, respectively. Also cuiA and cuiD locus were determined at 81 and 8min, respectively, on salmonella Genetic Map. The two regulators were identified as cuaR, and cudR, which controls cuiA and cuiD, respectively. cuaR, and cudR appeared as negative regulators because the expression of cuiA-lac-Z and cuiD-lacZ were increased. Copper adapted UK1 showed high resistance to H$_{2}$O$_{2}$, but cuiD did not. The product of the cudR locus was responsible for decreasing the tolerance to copper and H$_{2}$O$_{2}$. Furthemore cuiA and cuiD locus were found to be part of a regulon under the control of a trans-acting regulators, rpoS, oxyR and relA. Therefore, the results suggest CTR participate with oxidative stress on Salmonella.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.598-606
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• 2003

Salmonella encodes an enterotoxin (Stn) which possesses biological activity similar to the cholera toxin. Stn contributes significantly to the overall virulence of S. typhimurium in a murine model. The production of Stn is enhanced in a high-osmolarity medium and by contact with epithelial cells. In the present study, the in vitro and in vivo transcriptional regulations of the sin promoter revealed two promoters, P1 and P2. The P1 promoter identified by a primer extension analysis of stn mRNA exhibited a switching mechanism in vivo. Depending on the growth stage, transcription was initiated from different start sites termed $P1_S\;and\;P1_E$. $P1_S$, recognized by RNA polymerase containing ${\sigma}^S(E{\sigma}^S),\;and\;P1_E$, recognized by $E{\sigma}^70$, were activated during the stationary and exponential phases, respectively, while $P1_S\;and\;P1_E$ were both negatively regulated by CRPㆍcAMP and H-NS. Results revealed that $P1_S$ was the responsible promoter activated under a high osmolarity and low pH. The P2 promoter was identified 45 nucleotides downstream from $P1_E$ and negatively controlled by CRPㆍcAMP in vitro. No P2 activity was detected in vivo. The regulation of stn expression monitored using a Pstn::egfp fusion indicated that $E{\sigma}^S$ was required for the induction of stn and various factors were involved in stn regulation inside animal cells.

• Research in Plant Disease
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• v.22 no.1
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• pp.9-17
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• 2016

Nationwide survey for angular leaf spot (ALS) of strawberry caused by Xanthomonas fragariae, a quarantine disease in Korea, was performed in November 2012. In the survey, ALS was observed in eighty eight farmers' fields of Sukok, Jinju and Okjong, Hadong in Gyeongnam Province, and one field in Namwon of Jeollabuk Province. The infected field of Namwon closed immediately after the disease diagnosed ALS. In detailed survey of Sukok and Okjong areas during February 2012 to January 2015, ALS occurrence decreased from 45% farmer's fields on December 2012 to 5% on January 2015, and from 38% on November 2013 to 5% on January 2015, respectively. Phenotypic characteristics of the Korean strains were similar to those of the type strain of X. fragariae. A multilocus sequence analysis of Korean strains of X. fragariae was conducted using four genes; dnaK, fyuA, gyrB, and rpoD. All the Korean strains had the same sequences of the four genes. The concatenated sequences of the Korean strains shared 100% with that of the type strain of X. fragariae. All strawberry cultivars tested were susceptible to the strains of X. fragariae two weeks after inoculation. The inoculated sites were necrosis and expanded, which were rated 4 based on evaluation of inoculation site.

• Journal of Microbiology
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• v.35 no.4
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• pp.277-283
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• 1997

Promoters inducible by paraquat, a superocide-generating agent, were isolated from Escherichia coli using a promoter-probing plasmid pRS415 with promoterless lacA gene. Twenty one promoters induced by paraquat were selected and further characterized. From sequence analysis, thirteen of the promoters were mapped to their specific loci on the Escherichia coli chromosome. Several promoters were mapped to the upstream of known genes such as usgl, katG, and mglB, whose relationships with superoxide response have not been previously reported. Other promoters were mapped to the upstream region of unknown open reading frames. Downstream of HC 96 promoter are uncharacterized ORFs whose sequences are homologous to ABC-transporter subunits. Downstream of HC84 promoter is an ORF encoding a transcriptional regulator-like protein, which contains a LysR family-specific HTH (helix-turn-helix) DNA bindign motif. We investigated whether these promoters belong to the soxRS regulon. All promoters except HC96 were found to belong to the soxRS regulon. The HC96 promoter was significantly induced by paraquat in the soxRS deletion mutant strain. The basal transcription level of three promoters (HE43, HC71, HD94) significantly increased at the stationary phase, implying that they are regulated by RpoS. However, paraquat inducibility of all promoters disappeared in the stationary phase, suggesting that SoxRS regulatory system is active only in rapidly growing cells.