• 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.

• The Plant Pathology Journal
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• v.28 no.4
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• pp.390-400
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• 2012

Eight potato-producing provinces of Iran were surveyed during the growing seasons of 2004-2006 to detect the presence of Tomato yellow fruit ring virus (TYFRV), a tentative species in the genus Tospovirus. A total of 1,957 potato leaf samples were collected from plants with tospovirus-like symptoms of chlorotic or necrotic spots, chlorosis and necrosis. The samples were tested by enzyme-linked immunosorbent assay using TYFRV-specific antibodies. Among those tested, 498 samples (25.4%) were found to be infected with the virus. The virus was detected in 72.4% of the potato fields in all provinces surveyed. Thirteen potato isolates of TYFRV were selected for further biological and molecular studies. Based on their reactions on Nicotiana tabacum plants, the isolates were separated into two groups, namely L (local infection) and N (systemic infection). The nucleotide sequences of the nucleoprotein (N) genes of the isolates were determined and compared with the homologous sequences in Genbank. No recombination evidence was found in the isolates using different recombination-detecting programs. In the phylogenetic tree, the potato isolates fell into two major groups: IRN-1 and IRN-2 corresponding to the two biologically separated groups. This study shows for the first time the biological and phylogenetic relationships of geographically distant TYFRV isolates from potatoes in the mid-Eurasian country of Iran.

• Journal of Veterinary Clinics
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• v.25 no.6
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• pp.435-439
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• 2008

We evaluated the patterns of serology and fecal viral shedding for any differences by hemagglutination inhibition (HI) and real-time PCR on Korean CPV-2 isolates (CPV-2a-I, CPV-2a-V and CPV-2b). We successfully detected fecal viral shedding from samples extracted 2-3 d.p.i., regardless of the onset of clinical signs. In addition, the pattern of viral shedding differed depending on the CPV-2 isolates used for inoculation. We also observed differences in the serological pattern that was also depended on the CPV-2 isolates inoculated. The onset and amount of fecal viral shedding were not correlated with the level of antibody titers in this study. Our study is a valuable resource for understanding the different pathobiology of the CPV-2 isolates and the correlation between the patterns of serum antibody titer and fecal viral shedding.

• Journal of Microbiology and Biotechnology
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• v.11 no.1
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• pp.160-163
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• 2001

In order to investigate the role of bacterial chemotaxis in root colonization, the chemotaxis potential of bacteria isolated from spinach roots was compared with that of bacteria from nonhizosphere soil, with reference to the plant age (1,000 isolates), soil moisture conditons (1,400 isolates), and part of the root (200 isolates). The % CT (% occurrence of chemotaxis (+) isolates among total bacterial isoltes) of the root isolates significantlyfluctuated during the plant growth period, reaching a maximum after 10-15 days of growth. At this time period, the maximum % CT for the root isolates was around 70-80% CT under a soil moisture 50% WFP (% volume of water-filled pores in total soil pores), and then gradually reduced with an increasing % WFP. The results of the chemotaxis potential of each of the 100 islates from the spinach roots and nonrhizosphere soil under various % WFP demonstrated that the % CT of the root isolates were significantly higher than those of solates from the nonrhizosphere soil under a wide range of soil moisture content (35-80% WFP). Furthermore, the % CT value (80%) from the upper root was significantly higher than tht (55%) from the lower root. Compared with the % CT values of the roots, the values from the nonrhizosphere soil did not significantly vary relative to the plant age of % WFP. These results indicate that chemotaxis would appear to be a major factor in bacterial root colonization.

• Biomedical Science Letters
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• v.26 no.2
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• pp.120-126
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• 2020

Fluoroquinolone (FQ) resistant uropathogenic Escherichia coli (UPEC) have become a major problem in urinary tract infections (UTIs). The purpose of this study was to compare the quinolone resistance-determining region (QRDR) and plasmid mediated quinolone resistance (PMQR) determinants of FQ resistant UPEC between 1989 and 2010-2014. A total of 681 strains of UPEC clinical isolates was collected from Korean healthcare facility in 1989 (123 strains) and in 2010-2014 (558 strains). The minimum inhibitory concentrations (MICs) of FQs were determined by agar dilution method. QRDRs (gyrA, gyrB, parC and parE) and PMQR determinants (qnrA, qnrB, qnrS, aac(6')-Ib-cr and qepA) were analyzed polymerase chain reaction and sequencing method. Among 681 isolates, FQ resistant UPEC were 3 strains (2.4%) in 1989 isolates and 220 strains (39.4%) in 2010-2014 isolates. The rate of the FQ resistant UPEC strains in 2010-2014 isolates was increased than that of in 1989 isolates. UPEC isolates from 1989 and 2010-2014 were shown to carry mutations in gyrA (Ser83 and Asp87), gyrB (Ser464 and Thr469), parC (Ser80 and Glu84) and parE (Glu460, Ser458, Ile464 and Leu445). The most common mutations of QRDRs in 1989 isolates were Ser83Leu and Asp87Gly in gyrA and Ser80Ile in parC (2 strains: 66.7%) while those in 2010-2014 isolates were Ser83Leu and Asp87Asn in gyrA and Ser80Il2 and Glu84Val in parC (88 strains: 40.0%). PMQR determinants were detected only in 2010-2014 UPEC strains (47 strains: 21.4%).

• Parasites, Hosts and Diseases
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• v.55 no.5
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• pp.465-472
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• 2017

Recent trends of malaria in Thailand illustrate an increasing proportion of Plasmodium vivax, indicating the importance of P. vivax as a major causative agent of malaria. P. vivax malaria is usually considered a benign disease so the knowledge of this parasite has been limited, especially the genetic diversity and genetic structure of isolates from different endemic areas. The aim of this study was to examine the population genetics and structure of P. vivax isolates from 4 provinces with different malaria endemic settings in Thailand using 6 microsatellite markers. Total 234 blood samples from P. vivax mono-infected patients were collected. Strong genetic diversity was observed across all study sites; the expected heterozygosity values ranged from 0.5871 to 0.9033. Genetic variability in this study divided P. vivax population into 3 clusters; first was P. vivax isolates from Mae Hong Son and Kanchanaburi Provinces located on the western part of Thailand; second, Yala isolates from the south; and third, Chanthaburi isolates from the east. P. vivax isolates from patients having parasite clearance time (PCT) longer than 24 hr after the first dose of chloroquine treatment had higher diversity when compared with those having PCT within 24 hr. This study revealed a clear evidence of different population structure of P. vivax from different malaria endemic areas of Thailand. The findings provide beneficial information to malaria control programme as it is a useful tool to track the source of infections and current malaria control efforts.

• The Plant Pathology Journal
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• v.28 no.2
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• pp.207-211
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• 2012

It has been known that streptomycin resistance in bacteria can occur as a results of chromosomal mutation or through gene acquisition or both. Chromosomal mutations for resistances are point mutations in the rpsL gene, which alter ribosomal protein S12. Acquired resistance has occurred when an $Sm^R$ plasmid carrying transposon Tn5393 with tandem strA-strB gene is transferred by conjugation. A total of 686 isolates of Xanthomonas smithii subsp. citri causal agent of citrus canker disease were collected from 26 citrus orchards in Jeju Island in 2003 and 2004 seasons. Forty-nine of 111 isolates from streptomycin non-sprayed orchards in 2003 season were resistant to streptomycin. Of 107 isolates from orchards sprayed one time with streptomycin, 58 isolates were resistant, and 166 of 221 isolates from orchards sprayed two times with streptomycin were resistant. In 12 orchards sprayed three or more times with streptomycin, 219 of 247 isolates were resistant to streptomycin. Twenty-five isolates of X. smithii subsp. citri were surveyed to identify the mechanisms of streptomycin resistance in this study. Twenty-one of these 25 isolates were resistant to streptomycin, and it was proven by PCR assay that 18 of the 21 streptomycin resistant isolates have the strB gene. In sixteen of the 21 streptomycin resistant isolates, it was occurred a point mutation altered codon lysine (AAG)-41 of rpsL gene to arginine (AGG). The streptomycin-sensitive isolates easily acquired the resistance by mixed culture with resistant isolates. The strB gene was amplified from the isolates that acquired the resistance by mixed culture, and one isolate of them was also point-mutated in codon 41 of rpsL gene to be resistant. In this study, most of the streptomycin-resistant isolates of X. smithii sub sp. citri in Jeju island expressed the resistance by both chromosomal point mutation and gene acquisition, and the resistance was easily acquired through conjugation by culture mixed with streptomycin resistant and sensitive strains.

• Korean Journal of Veterinary Research
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• v.22 no.2
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• pp.121-138
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• 1982

The present study was conducted in order to investigate the role of yeast-like fungi in bovine mastitis. Attempts were made to isolate and identify yeast-like fungi from the milk from normal udders and those with clinical or subclinical mastitis and from feces. Also incuded in the study were trials for the pathogenicity of the isolates for laboratory animals and efficacy of an anti-fungal drug for the treatment of mastitis. A total of 133 isolates of yeast-like fungi was made from milk and feces and they were identified as Candida (C.) albicans (5 isolates), C. krusei (63 isolates), C. tropicalis (27 isolates), Torulopsis (T.) glabrata (10 isolates), Rhodotourla sp. (6 isolates), Hansenula sp. (6 isolates) and Pichia sp. (1 isolate). Sixty seven strains of yeast-like fungi were isolated from the milk of 64 quarters (4.3% of quarters examined) of 55 cows (14.3% of cows examined). C. krusei, C. tropicalis, C. pseudotropicalis, C. parapsilosis and T. glabrata were isolated as the causative agents from 20 quarters (1.3% of quarters examined) with clinical mastitis. C. krusei, C. tropicalis, C. albicans, C. pseudotropicalis, T. glabrata, Rhodotorula sp. and Hansenula sp. were isolated as the causative agents from 22 quarters (1.5% quarters examined) with subclinical mastitis. C. tropicalis, C. krusei, T. glabrata and Rhodotorula sp. were isolated as the contaminants from 22 normal quarters (1.5% of quarters examined). C. krusei, C albicans, C. tropicalis, C. pseudotropicalis, C. parapsilosis, T. glabrata, Hansenula sp., Rhodotorula sp. and Pichia sp. were isolated as the contaminants from feces and all of the species except Pichia sp. were isolated from milk of the same cows at the some time. Intramammary infusion of nystatin was effective for the treatment of mastitis caused by C. albicans, C. krusei, C. tropicalis, C. pseudotoropicalis, C. parapsilosis, T. glabrata and Rhodotorula sp. C. albicans, C. krusei, C. tropicalis, C. pseudotropicalis, T. glabrata, Hamsenula sp. and Pichia sp. were pathogenic for rat but C. parapsilosis and Rhodotorula sp. were not.

• Journal of Microbiology
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• v.45 no.4
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• pp.358-363
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• 2007

Multi-drug resistant Pseudomonas aeruginosa has been implicated in a variety of serious therapeutic problems in clinical environments. Among the 968 P. aeruginosa isolates obtained from two hospitals in Daegu, Korea, we acquired 17 isolates that were resistant to all available tested antimicrobial agents, with the exception of colistin (colistin-only sensitive). We characterized the antimicrobial susceptibilities, $metallo-{\beta}-lactamases$, and epidemiological relatedness among the colistin-only sensitive P. aeruginosa isolates. All colistin-only sensitive isolates were positive in the modified Hodge test and imipenem-EDTA synergy test, thereby indicating the production of $metallo-{\beta}-lactamases$. 11 isolates from the secondary hospital and six isolates from the tertiary teaching hospital harbored $bla_{VIM-2}$ and $bla_{IMP-1}$, respectively. The pulsed-field gel electrophoretic analysis of the SpeI-digested DNA from P. aeruginosa isolates indicated that two different clones of colistin-only sensitive P. aeruginosa originated from each hospital, and had spread within the hospital environment. Overall, colistin-only sensitive P. aeruginosa was detected in Korea for the first time, but no pan-drug resistant bacteria were identified. Nationwide surveillance is required in order to monitor the emergence of colistin-only sensitive or pan-drug resistant bacteria.

• The Plant Pathology Journal
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• v.37 no.4
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• pp.365-374
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• 2021

White rot or stem rot caused by Sclerotinia sclerotiorum is one of the most destructive fungal diseases that have become a serious threat to the successful cultivation of oilseed Brassicas. The study was designed with an aim to investigate the association between the pathogenic aggressiveness and pathogenicity determinants of this pathogen specifically in Brassica for the first time. For this, a total of 58 isolates of S. sclerotiorum from different geographical regions were collected and purified. These isolates were inoculated on a Brassica juncea cv. RL-1359 and they exhibited high level of variation in their disease progression. The isolates were grouped and then 24 isolates were selected for the biochemical analysis of pathogenicity determinants. The isolates varied significantly with respect to their total organic acids, oxalic acid production and pectin methyl esterase and polygalacturonase activity. The oxalic acid production corresponded to the disease progression of the isolates; the isolates with higher oxalic acid production were the more aggressive ones and vice-versa. This is, in our knowledge, the first study to establish a correlation between oxalic acid production and pathogenic aggressiveness of S. sclerotiorum on B. juncea. However, the pectinases' enzyme activity did not follow the trend as of disease progression. These suggest an indispensable role of oxalic acid in pathogenicity of the fungus and the potential to be used as biochemical marker for preliminary assessment of pathogenic aggressiveness of various isolates before incorporating them in a breeding program.