• The Korean Journal of Mycology
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• v.16 no.1
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• pp.9-15
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• 1988

Two kinds of toxins were demonstrated in the culture filtrate of H. sativum, and were called 'M' and 'D' toxins. The lettuce bioassay indicated that D-toxin caused less root growth inhibition than M-toxin. Chemical analysis indicated that M-toxin was a very unusual small peptide. D-toxin was shown to have chemical characteristics similar to helminthosporal based on ultraviolet, proton nuclear magnetic resonance and mass spectra. D-toxin was composed of at least two isomers.

• Journal of Microbiology
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• v.35 no.4
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• pp.323-326
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• 1997

Toxin protein from Ustilago maydis virus SH14 isolated in Korea was purified using ethanol precipitation, cation exchange, gel filtration and anion exchange chromatography. The molecular weight of the purified protein was estimated to be 8.3 kDa by SDS-PAGE analysis. The Nterminal sequence of the protein is L-G-I-N-C(K)-R-G-S-S-Q--C(K)-G-L-S-G which is highly homologous with that of P4 toxin, but the amino acid composition and electrophoretic mobility in a native PAGE of the toxin protein were totally different from those of P4 toxin respectively. The SH14 toxin was shown to have immunological cross-reactivity about 50% with P4 toxin when examined by Western hybridization.

• Journal of Microbiology and Biotechnology
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• v.27 no.8
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• pp.1449-1456
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• 2017

The prevalence and toxin characteristics of Bacillus thuringiensis isolated from 39 organic vegetables were investigated. B. thuringiensis was detected in 30 out of the 39 organic vegetables (76.9%) with a mean value of 2.60 log CFU/g. Twenty-five out of the 30 B. thuringiensis isolates (83.3%) showed insecticidal toxicity against Spodoptera exigua. The hblCDA, nheABC, and entFM genes were found to be the major toxin genes, but the ces gene was not detected in any of the tested B. thuringiensis isolates. The hemolysin BL enterotoxin was detected in all 30 B. thuringiensis isolates (100%). The non-hemolytic enterotoxin complex was found in 27 out of 30 B. thuringiensis isolates (90.0%). The B. thuringiensis tested in this study had similar toxin gene characteristics to B. cereus, which possessed more than one toxin gene. B. thuringiensis could have the potential risk of foodborne illness based on the toxin genes and toxin-producing ability.

• Korean Journal of Microbiology
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• v.30 no.3
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• pp.177-180
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• 1992

Among 120 U. maydis strains isolated in Korea 14 different strains containing specific viral dsRNA segments were analyzed for the distribution of dsRNA and the production of toxin protein. Several distinctive dsRNA patterns were identified, 9 cases of P type with typical H, M and L ds RNA and one case of non-P-type, the frequency of a specific isolate was decreased with increasing number of dsRNA segments. The presence of dsRNA had no effect on the cultural or morphological phenotype of the host. Two isolates containing P type dsRNA segments appeared to produce toxin protein (killer strains) which inhibited the growth of 4 isolates (sensitive strain) with different susceptibility. Two killer strains contain unique M dsRNA segment which may code for toxin protein. However, the presence of toxin-sensitive strains among dsRNA-free isolates was similar to that of ds RNA containing strains.

• The Korean Journal of Mycology
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• v.19 no.2
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• pp.128-135
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• 1991

Diethyl ether soluble toxin produced by H. sativum had the characteristics of helmin­thosporal as based on UV, GC-MS, and chemical analysis, but was not a helminthosporaI. It was speculated that it was a polymer of helminthosporal. It stimulated the productions of reducing sugar in the barly endosperm like gibberellic acid, but acted in the responses on the barley roots and coleoptiles like gibberellic acid. It seemed to be involved in Foliar and Root rot diseases with host specificity, based on the analysis of linear regression.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.8
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• pp.1077-1082
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• 2007

In this study, killer yeasts were isolated from traditional Nuruk to improve storage and suppress contaminant in food industry. Among killer yeasts, yeast K15 showed strong killer toxin activity and inhibited growth of Salmonella Typhimurium and Vibrio parahaemolyticus. Killer yeast K15 was identified with Pichia anomala by the Microlog TM 4.0 identification system and homology of the ITS sequence. Killer toxin generated from P. anomala K15 was inactivated by pronase E and suggested to be a protein. Therefore killer toxin of P. anomala K15 was thought to be safe in human such as bacteriocin. P. anomala K15 was sufficient for growth in 50% glucose and could be used to prevent contaminant in initial stages of alcohol beverage fermentation.

• Journal of Environmental Health Sciences
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• v.42 no.4
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• pp.255-265
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• 2016

Objectives: Mobile phones have become one of the most essential accessories in daily life. However, they may act as reservoir of infectious pathogens if they are used without hygienic practices in their handling. Therefore, this study aimed to isolate food-borne pathogens from mobile phones and investigate the characteristics of toxin genes and antibiotic susceptibility patterns. Methods: A total of 146 mobile phones were collected from 83 middle- and 63 high-school students in Busan. The surfaces of the mobile phones were aseptically swabbed. Results: Among the food-borne pathogens, Staphylococcus aureus, Bacillus cereus and Escherichia coli were detected in 26 (17.8%), 20 (13.7%) and four (2.7%) samples, respectively. There were no statistically significant differences according to school level, gender or phone type. None of four E. coli strains had pathogenic toxic genes. All of the B. cereus strains carried at least three different toxin genes among the nine enterotoxin and emetic toxin genes. Three out of 20 B. cereus strains (15%) possessed emetic toxin genes, which are rarely detected in food-poisoning cases in Korea. Among the 26 strains of S. aureus, the detection rate of staphylococcal enterotoxin genes, toxic shock syndrome toxin (tsst) and factors essential for methicillin resistance (femA) were 84.6%, 7.7% and 100%, respectively. In the antibiotic susceptibility test, there was no methicillin-resistant S. aureus (MRSA) or vancomycin-resistant S. aureus (VRSA). Conclusion: The results show that students' mobile phones in Busan were contaminated by food-borne pathogens which carried various toxic genes. Therefore, regular phone disinfection and hand hygiene is important in order to reduce cross-contamination.

• Journal of Environmental Health Sciences
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• v.38 no.6
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• pp.510-519
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• 2012

Objectives: This study was conducted in order to evaluate the microbiological contamination of the indoor air of the lunchrooms at child care centers and investigate the toxin genes and toxin production ability of food-borne pathogens. Methods: A total of 64 child care centers were sampled to test total aerobic bacteria, coliform bacteria, fungi, Staphylococcus aureus, Bacillus cereus and Salmonella spp. according to the Korea Food Code. All toxin genes of pathogens were detected using the Polymerase Chain Reaction method. The Sthaph. aureus enterotoxin was detected by a Staphylococcus aureus enterotoxin-reversed passive latex agglutination kit. The heamolysin BL (HBL) and non-heamolytic enterotoxin (NHE) produced by B. cereus were detected using a B. cereus enterotoxin-reversed passive latex agglutination kit and Bacillus diarrheal enterotoxin visual immunoassay kit, respectively. Results: The means of total aerobic bacteria and coliform bacteria were $1.91{\pm}1.84$ log CFU/plate and $0.47{\pm}0.62$ log CFU/plate, respectively. The mean of fungi also showed $0.59{\pm}0.71$ log CFU/plate. Among the pathogenic bacteria tested in this study, Staphy. aureus and B. cereus were detected in four (6.3%) and 21 (32.8%) out of 64 indoor air samples from lunchrooms in child care centers, respectively. All Staphy. aureus tested in this study possessed no toxin genes and did not produce enterotoxin. The detection rate of nheABC, hblCDA, entFM and ces toxin gene in B. cereus was 100, 57.1, 76.2 and 0%, respectively. B. cereus isolates were classified into four groups according to the presence or absence of toxin genes. The nheABC gene was the major toxin gene among B. cereus tested in this study. The HBL was detected in 11 out of 21 B. cereus isolates (52.4%) and three B. cereus isolates produced NHE (14.3%). Conclusion: The results indicated that the contamination by microorganisms in the indoor air of lunchrooms was unqualified to supply safe catering in child care centers. The ongoing control of indoor air quality is required.

• Journal of Microbiology
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• v.33 no.2
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• pp.154-159
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• 1995

SH-14, a novel killer strain of Ustilago maydis was isolated in Korea. It has been reported in other papers that the toxin specificity and double-stranded RNA pattern of SH-14 strain were different from other laboratory strains. In this paper, we analyzed the biochemical characteristics of U. maydis SH-14 virus. Three distinctive peaks were isolated from CsCl density gradient, designated as top (T), intermediate (I) and bottom (B) components. We found that the densities of each components, 1.285, 1.408 g/cm$\^$3/, respectively, are very similar to those of other strains. As previously reported by the analysis of dsRNA in each component, the dsRNA segments are separately encapsidated. Capsid protein of SH-14 virus consists of two proteins about 70 Kd shown by SDS-PAGE analysis. Electron microscopic examination of the virus particles revealed that UmV particles are very similar in size and morphology to all isolates as well as all lab-strains. In order to test immunological cross reactivity of UmV, werstern bolt analysis was carriedout with antiserum against A8 virus. All capsid protein had positive reaction against A8 antibody which indicated that UmV are immunologically cross-reactive with all isolates from Korea. The results presented in this paper may show that UmV isolated from SH-14 strain has very similar biochemical characteristics to those of other UmV. However, the difference in the toxin specificity and the molecular weight of toxin protein from the SH-14 strain has us to conclude that U. maydis SH-14 strain is a new killer type.

• Journal of Microbiology and Biotechnology
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• v.24 no.6
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• pp.725-731
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• 2014

The classical biotype strains of the Vibrio cholerae O1 serogroup harbor the biotype-specific cholera-toxin encoding phage (CTX) $CTX^{cla}$, and the El Tor biotype strains contain CTX-1. Although the classical biotype strains have become extinct, a remnant of classical CTX phage is transferred to the El Tor biotype strains. The prototype El Tor strains, which produce the biotype-specific cholera toxin, are now being replaced by atypical El Tor variant strains producing classical biotype cholera toxin. The genome sequences of the CTX phages in atypical El Tor strains indicate that the CTX phages in atypical El Tor strains are a mosaic of $CTX^{cla}$ and CTX-1. Before the emergence of atypical El Tor stains in the early 1990s, unusual pre-seventh pandemic strains were isolated in the US Gulf Coast between 1973 and 1986. These strains have characteristics of atypical El Tor strains since they are El Tor biotype strains containing $CTX^{cla}$, yet the genome sequence of this CTX phage indicates that it is different from $CTX^{cla}$ and is therefore classified separately as $CTX^{US\;Gulf}$.