• Korean Journal of Veterinary Research
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• v.36 no.4
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• pp.829-837
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• 1996

Clostridium perfringens has been identified as a causative organism in necrotic enteritis in chicken. The bacterium has been classified into five toxigenic types (A through E) based on the pattern of the production of major lethal toxins. Seroneutralization with mice or guinea pigs usually has been used to type the organism. Of the types, types A and C of the bacterium had been recognized as the major pathogenic types in chicken. In this experiment, we isolated nine field strains of C perfringens from chicken showing necrotic enteritis in clinical symptoms and pathologic findings and identified by biochemical tests. In order to type the organism, a multiplex polymerase chain reaction (PCR) was used with primers on major lethal toxin genes instead of seroneutralization. Amplification of only a toxin gene with the PCR suggested that the disease in chicken was due to type A of C perfringens in Korea. Furthermore, the PCR method can be replaced with seroneutralization to type C perfringens in future.

• Mycobiology
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• v.44 no.3
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• pp.155-161
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• 2016

The most economically important species used in a wide range of fermentation industries throughout Asia belong to Aspergillus section Flavi, which are morphologically and phylogenetically indistinguishable, with a few being toxigenic and therefore a major concern. They are frequently isolated from Korean fermentation starters, such as nuruk and meju. The growing popularity of traditional Korean alcoholic beverages has led to a demand for their quality enhancement, therefore requiring selection of efficient non-toxigenic strains to assist effective fermentation. This study was performed to classify the most efficient strains of Aspergillus section Flavi isolated from various types of traditional wheat nuruk, based on a polyphasic approach involving molecular and biochemical evaluation. A total of 69 strains were isolated based on colony morphology and identified as Aspergillus oryzae/flavus based on internal transcribed spacer and calmodulin gene sequencing. Interestingly, none were toxigenic based on PCR amplification of intergenic regions of the aflatoxin cluster genes norB-cypA and the absence of aflatoxin in the culture supernatants by thin-layer chromatography analysis. Saccharification capability of the isolates, assessed through ${\alpha}-amylase$ and glucoamylase activities, revealed that two isolates, TNA24 and TNA15, showed the highest levels of activity. Although the degrees of variation in ${\alpha}-amylase$ and glucoamylase activities among the isolates were higher, there were only slight differences in acid protease activity among the isolates with two, TNA28 and TNA36, showing the highest activities. Furthermore, statistical analyses showed that ${\alpha}-amylase$ activity was positively correlated with glucoamylase activity (p < 0.001), and therefore screening for either was sufficient to predict the saccharifying capacity of the Aspergillus strain.

• Korean Journal of Veterinary Research
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• v.44 no.4
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• pp.551-559
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• 2004

Shiga toxin-producing Escherichia coli (STEC) causes various clinical signs in human and animals, and has been indicated as a global enteropathogen with zoonotic importance. In this study, the feces of healthy pigs were collected from the slaughtered pigs of Daejon abattoir during the period from December 2001 to October 2002. Of 326 specimens, 13 STEC were confirmed by culture, PCR and colony hybridization. The isolates were further studied for toxin types, pathogenic factors, plasmid profiles, and antimicrobial resistance to characterize the genetic and toxigenic properties. In PCR, all of 13 isolates were evident to have shiga toxin gene (stx). Of 13 isolates stx1 gene was detected in 4 and stx2 gene in 9. The genes of eaeA, hlyA and rfbE were not present in any isolates. In colony hybridization using shiga toxin common primer (STXc), 2 to 9 per 100 colonies subcultured from 13 isolates showed the positive reaction. In the examination for plasmid profiles of the isolates, one to eleven plasmids with varying sizes of 1.0 Kb to 100 Kb were detected, and the 13 STEC could be classified into four groups by the plasmid patterns. The antimicrobial resistance patterns of the isolates were comparably corresponded with the plasmid profile patterns.

• Korean Journal of Clinical Laboratory Science
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• v.40 no.1
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• pp.48-54
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• 2008

Nine types of staphylococcal enterotoxin (SE) genes (sea~see, seg~sej), 3 types of virulence genes (eta, etb, tst), mecA and 16S rRNA as internal positive control were detected from 187 clinical MRSA (methicillin resistance Staphylococcus aureus) strains isolated from a variety hospitalized patients in Daegu and Gyeongsangbuk-do areas using the multiplex PCR. The frequency of the S. aureus strains harboring recently reported SE genes (seg~sej) were found to be very high (65.9%) and greater than that of the strains harboring classical SE (sea~see) genes (47.8%) as previously established. Taking into account that the newly described pairs form SE genes (i.e., sec+seg+sei, seg+sei) were many, in the other hand, single form SE genes (i.e., seg, seh, sei and sej) were rarely detected. The S. aureus with pairs form enterotoxigenic genes become more potentially toxigenic strains. Furthermore, this work indicated a systematic association between the seg and sei genes and their high incidence among the S, aureus strains, which suggests that these two SE's could be an important phylogenetic link among the staphylococcal enterotoxins.

• Research in Plant Disease
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• v.17 no.3
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• pp.280-287
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• 2011

This investigation was undertaken to survey toxigenic fungal contamination of various rice samples in 93 rice processing complexes (RPC) in Korea. Rice was grown in 2009 and the samples were collected in 2010. Seven types of rice samples such as unhusked, brown, blue-tinged, discolored, polished, half-crushed, and rice husks were obtained from each RPC. One-hundred and five grains of each sample were placed on PDA plates after surface disinfection. The incidence of fungal contaminants was 26.8%. Aspergillus spp. was the most dominant fungal contaminants and Fusarium spp. was the most frequently occurred in samples. The heaviest Fusarium contamination was found in unhusked grain, rice husks, and bare blue-tinged rice and followed by colored rice whereas broken rice was the least contaminated. Regional difference of fungal contamination was distinctive. Fusarium incidence in the rice samples from southern region of Korea including Jeolla and Gyeongsang Provinces was higher than those from central region including Chungcheong, Gyeonggi, and Gangwon Provinces. In contrast to Fusarium spp., Aspergillus spp. and Penicillium spp. were dominated in brown and polished rice samples and their incidences were more severe in central region than southern region. The major contaminants shown more than 1% of kernels infected were Aspergillus (5.0%), Fusarium (2.0%), Alternaria (1.4%), Dreschlera (1.3%), Penicillium spp. (1.3%), and Nigrospora spp. (1.0%). Collectotrichum, Pyricularia, Myrothecium, Epicoccum, Cladosporium, Moniliella, Gloeocercospora, Chaeto- mium, Curvularia, Phialopora, Acremonium, Gliomastix, Trichoderma, Rhizopus, Phomopsis, Paecilomyces, Genicularia, Geotrichum, Acremoniella, Rhizoctonia, Phoma, Oidiodendran, and Candida spp. were among the rest observed at low incidence. The major contaminants of rice samples were well-known as toxigenic fungal genera so toxin producibility of these fungal isolates is necessary to be examined in future. It is also needed to study Myrothecium spp. on species level as it was detected for the first time in rice.

• Research in Plant Disease
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• v.25 no.4
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• pp.157-163
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• 2019

This study aimed to assess the incidence and distribution of toxigenic fungi in Korean oat. Toxigenic fungi were isolated from oat samples collected from 12 oat fields from heading to harvest in 2017 and 2018. A total of 745 fungal colonies were isolated based on morphology and identified using marker genes. About 92% of the fungal isolates were Fusarium spp. and others were Penicillium (5.9%) and Aspergillus (2.1%). Fusarium isolates comprised mostly of F. asiaticum (83.1%), followed by F. incarnatum (5.4%), F. proliferatum (3.5%), F. fujikuroi (2.8%), F. tricinctum species complex (FTSC) 11 (1.5%) and F. graminearum (1.0%). About 97% of F. asiaticum was nivalenol type, and 3-acetyl deoxynivalenol (3.2%) and 15-acetyl deoxynivalenol (0.4%) types also were found. Pathogenicity test of the selected Fusarium isolates revealed that F. asiaticum isolates have a wide range of virulence depending on the tested plants. F. graminearum and FTSC 11 isolates from blighted spikelets were the most virulent in naked oat. All Fusarium isolates (n=18) except one (FTSC 11) produced nivalenol (0.2-7.6 ㎍/g), deoxynivalenol (0.03-6.1 ㎍/g), and zearalenone (0.1-27.0 ㎍/g) on rice medium. This study is first report that F. asiaticum causes Fusarium head blight disease of oat in Korea. These findings demonstrate the dominance of F. asiaticum in oat agroecosystems as in rice, wheat and barley in Korea.

• Journal of Food Hygiene and Safety
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• v.30 no.1
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• pp.51-58
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• 2015

Thirty one of Staphylococcus aureus isolated from perilla leaf cultivation areas in Miryang were investigated on the characteristics, such as enterotoxin genes and antibiotic susceptibility. Five toxin genes (sea, seb, sec, sed, and see) were examined by PCR method. Disc diffusion method was used to examine the antibiotic susceptibility of S. aureus by using 18 types of antibiotic discs with different concentrations. Among enterotoxin-encoding genes, sea and sed genes were co-detected from 4 isolates (12.9%), sed gene was founded in 9 isolates (29.0%), and see gene was founded in 1 isolate (3.2%). However seb and sec and tsst were not detected in any isolates. As a result of antibiotic susceptibility test, 7 isolates (22.6%) were resistant to 12 antibiotics (penicillin, ampicillin, oxacillin, amoxicillin-clavulanic acid, cefazolin, cephalothin, imipenem, gentamicin, tetracycline, ofloxacin, norfloxacin, and erythromycin). 2 isolates (6.5%) were resistant to 5 antibiotics (penicillin, ampicillin, amoxicillin-clavulanic acid, gentamycin, and telithromycin). MRSA (Methicilline Resistant Staphylococcus aureus) was founded in packing vinyl, hands, and perilla leaves.