• The Plant Pathology Journal
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• v.25 no.4
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• pp.317-321
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• 2009

Sensitivity to the new carboxylic acid amide fungicide, mandipropamid, of Phytophthora capsici causing pepper Phytophthora blight was determined on 187 isolates collected in Korea over 3 years, from 2005 to 2007. All isolates were sensitive to mandipropamid, with $EC_{30}$ values for growth of mycelia ranging from 0.001 to $0.037\;{\mu}g/ml$. Among the isolates, 147 (79.0%) isolates were sensitive to metalaxyl, whereas others were resistant to this fungicide. Mandipropamid had the same effect on mycelium growth of both metalaxyl-sensitive and metalaxyl-resistant isolates, indicating an absence of cross-resistance between these two fungicides. Comparison of the sensitivities of P. capsici isolates showed a positive correlation between sensitivity to mandipropamid and dimethomorph ($r^2$=0.8533). The results of this study indicate that there is no evidence for development of resistance to mandipropamid in this population of P. capsici isolates collected in Korea.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1228-1235
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• 2011

We compared the gene expression among four clinical and five environmental V. vulnificus isolates, using a cDNA microarray containing 131 genes possibly associated with pathogenicity, transport, signal transduction, and gene regulations in the pathogen. cDNAs from total RNAs of these isolates were hybridized into the cDNA microarray using the cDNA of the wild-type strain MO6-24/O as a reference. We focused on selecting differentially expressed (DE) genes between clinical and environmental isolates using a modified t-statistic. We could detect two statistically significant DE genes between virulent isolates and less-virulent isolates with a marginal statistical significance (p-value of 0.008). These were genes putatively encoding pilin and adenlyate cylase. Real time-PCR confirmed that these two selected genes transcribed in significantly higher levels in virulent isolates than in less-virulent isolates. Mutants with lesions in the gene encoding pilin showed significantly higher $LD_{50}$ values than that of wild type.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.199-206
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• 2008

Four hundred and thirteen oxytetracycline-resistant bacteria were recovered from six freshwater giant prawn farms with a history of oxytetracycline use. Most oxytetracycline-resistant isolates were Gram-negative bacteria. Six groups of oxytetracycline-resistant bacteria were classified using cluster analysis based on a comparison of levels of oxytetracycline resistance. Complex fingerprint patterns were obtained for 71 isolates studied. In general, the band patterns of isolates from different ponds were very similar, and the data indicated that the isolates were closely related. The exploration for cross-resistance found that most of the 71 oxytetracycline-resistant isolates were also resistant to tetracycline and chlortetracycline, but had a relatively low resistance to doxycycline. Many isolates showed higher chlortetracycline resistance than oxytetracycline resistance. Additionally, the oxytetracycline-resistant isolates were examined for the presence of tetracycline resistance (tet) genes. Fifty percent of the isolates carried one of the 14 known tet genes examined. The most common determinants were TetA and TetD. However, TetB, TetC, TetE, TetK, TetL, and TetM were also found with various frequencies.

• Journal of Microbiology and Biotechnology
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• v.27 no.6
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• pp.1157-1162
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• 2017

The goal of this study was to identify and characterize selected Trichoderma isolates by metabolic profiling and enzyme assay for evaluation of their potential as biocontrol agents against plant pathogens. Trichoderma isolates were obtained from the Rural Development Administration Genebank Information Center (Wanju, Republic of Korea). Eleven Trichoderma isolates were re-identified using ribosomal DNA internal transcribed spacer (ITS) regions. ITS sequence results showed new identification of Trichoderma isolates. In addition, metabolic profiling of the ethyl acetate extracts of the liquid cultures of five Trichoderma isolates that showed the best anti-Phytophthora activities was conducted using gas chromatography-mass spectrometry. Metabolic profiling revealed that Trichoderma isolates shared common metabolites with well-known antifungal activities. Enzyme assays indicated strong cell wall-degrading enzyme activities of Trichoderma isolates. Overall, our results indicated that the selected Trichoderma isolates have great potential for use as biocontrol agents against plant pathogens.

• Microbiology and Biotechnology Letters
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• v.25 no.2
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• pp.159-165
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• 1997

We collected 3,237 plant samples, mainly leaves of various trees, from many provinces in Korea and a total of 1,925 Bacillus thuringiensis isolates were obtained and characterized. The isolates were characterized in terms of crystal morphology, PAGE pattern of the toxin proteins, plasmids pattern, biochemical characteristics, and bioassay. The microscopic observation showed that 49.1% of the isolates have bipyramidal shape crystals, 7.1% of spherical shape crystals, 1.4% of rhomboidal shape crystals, and others have small or amorphous inclusions. The insecticidal activities of the spore-crystal mixtures of isolates were tested against Plutella xylostella, Bombyx mori, Culex pipiens, and Agelastica coerulea. Bioassay showed that 51.3% of the isolates were shown to be active; lepidopteran-specific (44.8%), dipteran-specific(4.9%) and coleopteran-specific (1.6%). The remainder(48.8%) did not show any activity against the insects we tested. Interestingly though, some of these non-active isolates were shown to have bipyramidal crystals. By serotyping 22 isolates of our collection, we found that there are various kind of subspecies such as aizawai, amagiens, canadensis, darmstadiensis, galleriae, finitimus, kurstaki, morrisoni and neoleonensis, and three isolates have been classified into a new serotype, H49, and one of them, the type strain, named subsp. muju. From this study it was found that phylloplane is a good source for the isolation of Bacillius thuringiensis, and Bacillus thuringiensis is distributed widely in Korea.

• Korean Journal of Veterinary Service
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• v.40 no.1
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• pp.41-46
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• 2017

The purpose of this study was to investigated the fluoroquinolone (FQ) resistance and presence of gyrA and grlA gene in 87 Staphylococcus pseudintermedius isolates obtained from clinical samples of dogs and cats. Also, the profiles of FQ resistance compared with methicillin resistant S. pseudintermedius (MRSP) isolates. FQ resistance was observed for enrofloxacin (41.4%), ciprofloxacin (39.1%), norfloxacin (36.8%), ofloxacin and levofloxacin (32.2%, respectively), and moxifloxacin (31.0%). Thirty-eight (43.7%) of 87 S. pseudintermedius isolates were resistant to more than one FQ. Twenty-six (64.5%) of 38 FQ resistant isolates were resistant to all the six FQ tested. Of 38 FQ resistant isolates, gyrA gene was detected in all isolates but grlA gene was not found. Moreover, 19 MRSP isolates were resistant to enrofloxacin (63.2%), ciprofloxacin (57.9%), norfloxacin (52.6%), and ofloxacin, levofloxacin and moxifloxacin (47.4%, respectively). FQ resistance were highly prevalence in S. pseudintermedius isolates from dogs and cats. Our results emphasize the prudent use of antimicrobial agents to companion animals is necessary for prevent antimicrobial resistance.

• The Plant Pathology Journal
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• v.24 no.1
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• pp.17-23
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• 2008

A total of 33 isolates of Colletotrichum species obtained from pepper, apple, and strawberry in 2001 and 2002 were identified based on mycological characteristics, responses to fungicides carbendazim and the mixture of carbendazim and diethofencarb, and nucleotide sequence analysis of internal transcribed spacer (ITS) regionMost of the Colletotrichum isolates from pepper could be identified as C. acutatum. The pepper isolates produced grey white mycelia that gradually changed to dark gray. The conidia were variable in size, and almost cylindrical in shape with at least one rounded end. They could grow on PDA amended with carbendazim or with the mixture of carbendazim and diethofencarb at $10{\mu}g/ml$, to which the isolates from apple and strawberry were very sensitive. A part of the ITS regions from the Colletotrichum isolates was amplified with the specific primers designed for C. acutatum (Ca1-1) or C. gloeosporioides (Cg1-3). A primer pair of Ca1-1 and a universal primer (ITS4) amplified a 496-bp DNA fragment from all of the pepper isolates examined and one apple isolate. Taken together, it is conclusive that the Colletotrichum isolates causing the typical lesion of anthracnose on pepper fruits are C. acutatum.

• The Korean Journal of Mycology
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• v.24 no.4 s.79
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• pp.280-292
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• 1996

The fungal isolates of Mucorales, directly collected from Korean traditional raw materials of Nuruk (raw material for Korean rice wine) and Meju (raw material for Korean soysauces), were compared with those of Rhizopus oryzae purchased. The fungal isolates of Rhizopus, Mucor, and Absidia mostly identified as based on the morphological observations, were evaluated with the PCR-polymorphic bands. The PCR-polymorphic bands of the genomic DNA reacted with the primers of OPD series tenmer were various, but showed averaged 4 to 6 in the agarose-electrophoresis. The dissimilarity coefficient (DC) between two isolates were compared by the cluster analyses, dendrogams and polar ordinations. The isolates of R. oryzae known. showed several groupings within the lower value of DC and were divided to two groups of amylo-process and other fungi with other purposes. The isolates unidentified were identified by the DC made of this results. Taxonomy of these isolates made by the morphological observations were consistent with those resulted above in most case but not in all aspects. More works were needed with the isolates known for detail informations of Mucorales.

• The Plant Pathology Journal
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• v.18 no.3
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• pp.156-160
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• 2002

Cymbidium orchids with blight and rot symptoms were collected, and a total of 63 isolates of Fusarium app. was obtained from pseudobulbs, roots, and leaves of the diseased plants. The isolates were identified based on their morphological characteristics. Out of the 63 isolates of Fusatium sup., 51 isolates were identified as F. oxysporum, 10 isolates as F. solani, and the rest as F. proliferatum. F. oxysporum was isolated from all the Cymbidium spp., while F. solani and F. proliferatum were isolated only from Cymbidium ensifolium and C. ginatum, respectively. Isolates of the three Fusarium spp. were tested for pathogenicity to their hosts by artificial inoculation. The strongly pathogenic isolates of Fusarium spp. induced severe dry rot of pseudobulbs and roots of the host plants. The symptoms progressed up to the basal part of the leaves, which later caused blight of the entire plant. The dry root symptoms induced on the plants by artificial inoculation with the isolates of Fusarium app. were similar to those observed in the growers'greenhouses. This is the first report of dry rot of Cymbidium spp. caused by F. oxysporum, F. solani, and F. proliferatum in Korea.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.536-542
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• 1998

Ten isolates of the orchid mycorrhizal fungi were isolated from the roots of Korean native orchid plants (Cymbidium goeringii) which inhabitate mainly in southern and western areas of Korea. The growth rates and color of the isolates in potato dextrose agar (PDA) were various. Microscopic observations of the hyphae isolated were identified as Rhizoctonia repens and R. endophytica var endophytica or their related species. R. repens was isolated from the roots of the Korean native orchids, but R. endophytica var endophyica was only isolated from the roots of the commercial orchids introduced from foreign countries. Also, the polymorephic patterns of genomic DNA extracted from selected isolates were compared with those of DNA extracted from the orchid mycorrhizal fungi isolated previously and similar band patterns were observed among those isolates. Five isolates of R. repens were selected and cultured at the oatmeal agar for investigating their symbiosis with orchid plants. The symbiotic specificity between orchid plants and isolated orchid mycorrhizal fungi was observe by growing orchids about six months in the greenhouse. The symbiotic responses of the commercial orchid plants with selected isolates were quite different form different isolates due to the genetic variations.