• The Plant Pathology Journal
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• v.27 no.4
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• pp.378-384
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• 2011

Tomato yellow leaf curl virus (TYLCV), a member of genus Begomovirus, was isolated in Korea in 2008. We sequenced and analyzed the DNA-A of 51 TYLCV isolates from Korea, and 13 of the TYLCV isolates were selected as type representatives of TYLCV from six Korean provinces. The 13 TYLCV isolates were classified into Korea Group 1 (KG1, nine isolates) and Korea Group 2 (KG2, four isolates) based on the results of phylogenetic analysis and genome size (2774 and 2781 nucleotides, respectively). A recombination detection program 3 (RDP3) revealed two recombinations between the TYLCV Korea isolates and other TYLCV isolates [Thailand (AF206674), Iran (AJ132711), and Israel (X76319)]. TYLCV Jeju isolate was characterized by two recombination events (E1 and E2) caused by the presence of E1 in ORF V1 and C3, which may seem to be the mutations of the high nucleotide transversion and transition rate. Collectively, our results suggest that the occurrence of nucleotide transversions and transitions in TYLCV DNA-A might have induced novel recombination events within the TYLCV Korea isolates.

• Journal of Microbiology and Biotechnology
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• v.18 no.9
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• pp.1584-1589
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• 2008

Although resistance of Helicobacter pylori to clarithromycin is a major cause of failure of eradication therapies, little information is available regarding gene mutations of clarithromycin-resistant primary and secondary H. pylori isolates in Korea. In the present study, we examined gene mutations of H. pylori 238 rRNA responsible for resistance to clarithromycin. DNA sequences of the 238 rRNA gene in 21 primary clarithromycin-resistant and 64 secondary clarithromycin-resistant strains were determined by PCR amplification and nucleotide sequence analyses. Two mutations of the 238 rRNA gene, A2143G and T2182C, were observed in primary clarithromycin-resistant isolates. In secondary isolates, dual mutation of A2143G+T2182C was frequently observed. In addition, A2143G+T2182C+ T2190C, A2143G+T2182C+C2195T, and A2143G+T2182C+A2223G were observed in secondary isolates. Furthermore, macrolide binding was tested on purified ribosomes isolated from T2182C or A2143C mutant strains with $[^{14}C]$erythromycin. Erythromycin binding increased in a dose-dependent manner for the susceptible strain but not for the mutant strains. These results indicate that secondary isolates show a greater variety of 238 rRNA gene mutation types than primary isolates, and triple mutations of secondary isolates are associated with A2143G+T2182C in H. pylori isolated from Korean patients.

• The Plant Pathology Journal
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• v.21 no.4
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• pp.369-376
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• 2005

Turnip mosaic virus (TuMV) is an infectious viral pathogen on the cruciferous crops, predominantly Chinese cabbage (Brassica campestris subsp. pekinensis) and radish (Raphanus sativus). On the basis of the symptom development in selective differential hosts from indicator host species, Chinese cabbage and Korean radish inbred lines, the representative eight isolates of TuMV were divided into two major groups/or six types. Group I includes Th 1, Ca-ad7, and Cj-ca2-1 isolates, while group II includes the other isolates (rg-pfl, r 9-10, Rhcql-2, Stock and Mustard). According to the molecular phylogenetic analysis, these isolates, however, divided into two groups and two independent isolates. Phylogenetic analysis indicated that four isolates (Tu 1, r9-10, Stock and Rh-cql-2) formed a distinct phylogenetic group, and the other two isolates (Ca-ad7 and Cj-ca2-1) also formed another group. Mustard and rg-pfl isolates did not seem to have any relationship with these two groups. Taken together, these results indicated that virulence differentiation on host plants, molecular phylogenetic analysis of the nucleotide and the deduced amino acid of TuMV coat proteins did not show any relationship. The multi-resistant lines, Wonyae 20026 and BP058 in Chinese cabbage represent valuable genetic materials that can be used for crucifer breeding programs on TuMV resistance, but not in Korean radish.

• The Korean Journal of Mycology
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• v.25 no.1 s.80
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• pp.35-45
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• 1997

The yellow fungal isolates inhabiting at the cereals (Hwang-Kuk, HK-fungi) were widely collected from the mejus and nuluks in Korea; the meju is a raw material for Korean traditional foods for soysauce and soypaste, and the nuluk is a raw material for Korean traditional rice wine. These isolates, well known as an Aspergillus oryzae producing amylase for Korean rice wine or producing protease for soybeans, were compared with Aspergillus species known. All isolates were microscopically observed to be a species of A. oryzae or its related, but to be difficult to be identified. Thus, RAPD-DNA techniques were applied for these isolates and analyzed with nummerical values using NT-system, or Ecological programs or Factorial analyses. Several common bands of RAPD-DNA in the 28 isolates were synthesized with the different OPD primers and speculated to be used for identification of HK fungi. The HK-fungi isolated were revealed to belong to the group of A. flavus previously defined. Particularly, the isolates collected from mejus were analyzed to be more closed to A. flavus, The species of A. flavus, A. oryzae and A. sojae were grouped at the values lower than those indicating the diversity of species. In other words, these three fungal species were not distinguishable and all isolates known as a HK-fungus were very closed to A. flavus, All isolates were not diversified at groupings of RAPD-DNA, and considered to be not the natural flora at the mejus or nuluks. The meju or nuluk having the above fungi as the fungal flora were speculated to be not termed "Korean traditional foodstuffs".The yellow fungal isolates inhabiting at the cereals (Hwang-Kuk, HK-fungi) were widely collected from the mejus and nuluks in Korea; the meju is a raw material for Korean traditional foods for soysauce and soypaste, and the nuluk is a raw material for Korean traditional rice wine. These isolates, well known as an Aspergillus oryzae producing amylase for Korean rice wine or producing protease for soybeans, were compared with Aspergillus species known. All isolates were microscopically observed to be a species of A. oryzae or its related, but to be difficult to be identified. Thus, RAPD-DNA techniques were applied for these isolates and analyzed with nummerical values using NT-system, or Ecological programs or Factorial analyses. Several common bands of RAPD-DNA in the 28 isolates were synthesized with the different OPD primers and speculated to be used for identification of HK fungi. The HK-fungi isolated were revealed to belong to the group of A. flavus previously defined. Particularly, the isolates collected from mejus were analyzed to be more closed to A. flavus, The species of A. flavus, A. oryzae and A. sojae were grouped at the values lower than those indicating the diversity of species. In other words, these three fungal species were not distinguishable and all isolates known as a HK-fungus were very closed to A. flavus. All isolates were not diversified at groupings of RAPD-DNA, and considered to be not the natural flora at the mejus or nuluks. The meju or nuluk having the above fungi as the fungal flora were speculated to be not termed 'Korean traditional foodstuffs'.

• Journal of Microbiology and Biotechnology
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• v.8 no.5
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• pp.490-496
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• 1998

Random amplified polymorphic DNA (RAPD) markers were used to survey genetic variability among 34 Botrytis cinerea isolates from nine different host plants in Korea. For RAPD analysis, 115 arbitrary decamer primers were initially screened for polymorphic major DNA bands with 11 representative B. cinerea isolates. Eleven primers that initially detected polymorphisms were tested a second time with additional 23 isolates of B. cinerea as well as one isolate of Botrytis squamosa as an outgroup. The RAPD analyses revealed that all isolates except one showed different molecular phenotypes. Dendrograms obtained from dissimilarity matrices using the unweighted paired group method of arithmetic means (UPGMA) showed the 36.4% to 90.0% similarity among all B. cinerea isolates. The B. squamosa isolate showed the least similarity to all B. cinerea isolates. The cluster analyses indicated no correlation among all the characteristics examined including molecular phenotypes, host and geographic origins, year of isolation, or pathogenicity. The RAPD data suggest that a high level of genetic variation exists among Korean populations of B. cinerea and it seems to be caused by heterokaryosis among preexisting molecular phenotypes.

• Korean Journal of Veterinary Research
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• v.49 no.3
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• pp.195-200
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• 2009

Avian pathogenic Escherichia coli (APEC) is an important bacterial pathogen of chickens and causes colibacillosis such as airsacculitis, perihepatitis, omphalitis, peritonitis, salpingitis, and pericarditis. As the transfer of antibiotic resistance from animal to humans can be possible, surveillance on antibiotic resistance of APEC is very important. A total 34 APEC isolates from diseased chickens during the period from 2007 to 2009 were obtained. The susceptibility of the isolates to 13 antibiotics was determined by disc diffusion assay. Resistance to erythromycin was found in 97.1% of APEC isolated, followed by resistance to tetracycline (85.3%), doxycycline (82.3%), ampicillin (73.5%), sulfisoxazole (67.6%), enrofloxacin (67.6%), ciprofloxacin (64.7%), norfloxacin (61.7%) trimethoprim/sulfamethoxazole (52.9%), gentamycin (26.5%), amoxicillin (8.8%), colistin (5.9%), and amikacin (2.9%). The blaTEM genes were detected in 25 (100%) of the 25 ampicillin-resistant APEC isolates. Among the 29 tetracycline-resistant APEC isolates, tetA and tetB genes were detected in 18 (62.1%) and 9 (31%) isolates, respectively. Twenty six (76.5%) isolates were multiresistant to at least 6 antibiotics and seven (20.1%) isolates were multiresistant to at least 10 antibiotics. This results indicated that multiple antibiotic-resistant APEC is widespread in chicken flocks in Korea.

• Korean journal of applied entomology
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• v.11 no.1
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• pp.5-9
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• 1972

The experiment was conducted to investigate the physiological characteristics on 16 Isolates of bacterial wilt pathogen, pseudomonas solanacearum E.F. Smith, those obtained from infected stems of tomatoes, hot-Peppers and eggplants. PSA and Sucrose medium favoured by the most of the isolates, and various degree of gelatin liquefaction occurred by each of nine isolates those alble to liquefy gelatin among 16 isolates tested. The most of the isolates except one, did not reduce methylen blue. All isolates did not utilize lactose, saccharose, and starch, although all isolates utilize the galactose. The utilization of dextrin, esculin, glucose, mannitol, raffinose and salicin was depended on each isolate.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.596-604
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• 2019

Vibrio parahaemolyticus causes food poisoning, mainly via marine fisheries products. We investigated the virulence factors and drug resistance of V. parahaemolyticus isolated from fisheries products purchased from the Yeosu Fisheries Market. The isolates were identified using a variety of biochemical tests and the detection of toxR and hns gene. The presence of the virulence factor-encoding genes tdh and trh in the isolates was also investigated by PCR. The resistance of the isolates to 13 antibacterial agents was tested using the disc-diffusion method and carriage of β-lactamase genes and class 1 integrons by ampicillin-resistant isolates was investigated by PCR. Four of seventeen isolates identified as V. parahaemolyticus by biochemical tests produced a species-specific PCR band. Those isolates showed >98% 16S rRNA gene sequence homology with V. parahaemolyticus and only one isolate harbored the tdh gene. All of the V. parahaemolyticus isolates were resistant to ampicillin and amoxicillin; moreover, VPA0477, a class A β-lactamase gene, and class 1 integrons were detected. Therefore, V. parahaemolyticus from fisheries products represents a low risk to human health. Also, V. parahaemolyticus is likely to develop multidrug resistance because it has class 1 integrons.

• Korean Journal of Veterinary Service
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• v.20 no.2
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• pp.151-159
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• 1997

This study was carried out to isolate of causative agents from CMT-positive and mean somatic cell count(SCC) $\geq$500,000 cells/ml mastitic milk, and evaluate to antimicrobial susceptibility of isolates in Iksan branch area from January to November, 1996. 1. The CMT-positivity(SCC 500,000 cells/ml) of 610 heads was 36.2% (221), and of 2,373 quarter milks was 16.1% (383). 2. The Gram-positive isolates were 153 strains which was Staphylococcus sp (115), Micrococcus sp (18), Streptococcus sp (10), Listeria monocytogenes (5) and Enterococcus faecalis(5). 3. The Gram-negative isolates were 66 strains including E coli(14), Yersinia sp (13), Shigella sp(8), Enterobacillus sp(8), Cedecea sp(5), Pseudomonas aeruginosa(5), Proteus sp(5), Klebsiella sp(4), Salmonella sp(2), kluyvera ascorbate(1) and Tatumella ptyseos (1). 4. The Gram positive strains of isolates were moderately susceptible to T/s, Cp, Fd, Imp, Aug, Rif, Cft and Va. And the Gram negative strains of Isolates were moderately susceptible to T/s, Cp, Imp, Pi and Ti, In order. 5. Multiple antimicrobial resistant patterns were encountered 62 and 36 from Gram positive and negative isolates, respectively.

• Korean Journal Plant Pathology
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• v.10 no.4
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• pp.249-253
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• 1994

Twenty six isolates of Magnaporthe grisea originated from rice and other gramineous hosts Korea were tested for mating type with MAT1-1 and MAT1-2 standard isolates. Ninety three and 64% of rice and grass isolated mated and produced perithecia with standard isolates, respectively. Both mating types were found from rice and non-rice isolates, but MAT1-1 allele of M. grisea was predominant in Korea.