• Journal of Food Hygiene and Safety
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• v.13 no.3
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• pp.313-317
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• 1998

This study was perfonned to investigate the possible effect of Bacillus subtilis which is the predominant species of bacteria in Korean soy sauce, soy paste, and Meju (soybean cake) on the growth and aflatoxin production of Aspergillus parasiticus ATCC 15517. The microorganisms were grown in a modified APT broth and incubated at $30^{\circ}C$ for 12 days. Aflatoxins were determined using high performance liquid chromatography (HPLC). A remarkable inhibition of the growth of Aspergillus parasiticus was observed during the incubation period when in the presence of B. subtilis (mixed culture). Dry mycelial weight in the mixed culture was significantly reduced by 85.3% in comparison to the control at the end of the incubation period (p<0.01). Lower levels of aflatoxins were found in the mixed culture than in the monoculture. At the end of the incubation period aflatoxin production was significantly inhibited by more than 50% (p<0.05). These results indicate that B. subtilis mainly inhibites the growth and aflatoxin production of toxigenic Aspergillus in Meju, soy sauce and soy paste. Although its effect on aflatoxin production was less pronounced, we could expect more inhibition by another bacteria related with fermentation in Meju.

• 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.

• Journal of Environmental Health Sciences
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• v.42 no.1
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• pp.10-18
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• 2016

Objectives: Microcystin (MC) produced during cyanobacterial blooms is a worldwide problem presenting a serious health threats to humans and ecosystems. During July through October of 2013, the Ilwol Reservoir experienced a high biomass of phytoplankton (maximum $211.7mg/m^3$ of Chlorophyll-a) containing the toxigenic cyanobacterium Oscillatoria sp. The aim of this study is to analyze MC concentration in the reservoir water, as well as in representative fish species (Carassius cuvieri, Carassius auratus, Channa argus). We also evaluated the human health risk of exposure to MCs accumulated in the fish. Methods: Concentrations of MCs in the water and fish samples were analyzed by liquid chromatography with a triple quadrupole tandem mass spectrometer (LC/MS/MS) and enzyme-linked immunosorbent assay (ELISA). Results: The total levels of four MC variants, including MC-LR, MC-RR, MC-YR and MC-LA were below the WHO drinking water guideline limit (1 ug MC-LR per liter) both for the dissolved and particulate fraction present in the water samples. The mean MC concentrations in the livers of all species were significantly higher than in the gills (p < 0.01) and muscles (p < 0.05). The values of estimated daily intake of MCs in muscles, the edible part of the fish, would be only $0.005-0.015{\mu}g/kg{\cdot}day$, much lower than WHO's provisional tolerable daily intake of $0.04{\mu}g/kg{\cdot}day$. Conclusion: This study suggests that, owing to the spatial distribution or temporal variation of MC, there is a need for careful monitoring of cyanotoxin in reservoir water and aquatic animals to protect public health.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.117-124
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• 2019

Vibrio cholerae is a very important pathogenic bacterium that has to be monitored in seafood and ships' ballast water. Various methods have been developed to identify this bacterium, yet these methods are time-consuming and have limitations for their sensitivity to detect contamination. The purpose of the present study was to develop a robust and reliable method for identifying V. cholerae. Peptide nucleic acid (PNA) probes were developed to use for PNA-based asymmetrical real-time PCR techniques. The toxigenic Cholera enterotoxin subunit B (ctxB) gene was selected as a target for detecting V. cholerae and the gene was synthesized as a positive template for conventional and real-time PCR. Real-time PCR primers and PNA probes were designed and standard curves were produced for the quantitative analysis. The selected PNA probes reacted specifically to V. cholerae without any ambiguity, even among closely related species, and the detection limit was 0.1 cfu/100 mL. Taken together, the PNA probes and asymmetrical qPCR methods developed in this present study could contribute to the rapid, accurate monitoring of V. cholerae in marine environments, and as well as in seafood and ships' ballast waters.

• Korean Journal of Microbiology
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• v.31 no.4
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• pp.312-317
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• 1993

A total of 110 Fusarium graminearum isolates were obtained from corn and barley samples which were collected from Kangwon province and the southern part of Korea, respectively. The isolates were tested for trichothecene and zearalenone (ZEA) production in rice culture. The incidences of trichothecene production by 51 isolates of F. graminearum from corn were 64.7% for deoxynivalenol (DON), 7.8% for 3-acetyldeoxynivalenol (3-ADON),33.3% for 15-acetylde-oxynivalenol (15-ADON), 21.6% for invalenol (NIV), and 13.7% for 4-acetylnivalenol (4-ANIV). DON producers frequently co-produced 15-ADON rather than 3-ADON. On the other hand, the incidences of trichothecene production by 59 isolates of F. graminearum from barley were 71.2% for NIV, 61.0% for 4-ANIV, and only one isolate produced DON and 3-ADON. The incidences and mean levels of ZEA producers were 32.0% and 71.$\mu$g/g for the isolates from corn, and 29.0% and 74 .$\mu$g/g for the isolates from barley. There was a great regional difference in trichothecene production of F. graminearum isolates between Kangwon province and the southern part of Korea.

• Journal of Life Science
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• v.20 no.7
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• pp.1073-1077
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• 2010

Fungi, including allergenic, pathogenic or toxigenic species, may have direct effects on human health, interfere with the disinfection process and maintenance of chlorine residual, and add to taste and odor problems. We surveyed distribution of waterborne fungi from raw water in Busan metropolitan city using the EPA standard method. According to the survey, conducted from March 2008 to October 2008, the number of fungi in raw water was high in September and low in April. Quantitative enumeration of fungi per 100 ml of raw water ranged from 5 to 64 CFU, and a higher number was detected in the Mulgum region compared to the Maeri region. Total fungi numbers highly correlated with pH, water temperature and total coliform in this area. Predominant fungi genera grown in medium were identified as Aspergillus, Penicillum, Histoplasma, Rhizopus, Trichophyton, Mucor and Sporthrix species. Aspergillus flavus and Penicillum notatum were particularly dominant in both areas. There were a total of 6 and 9 species detected in the Mulgum and Maeri regions respectively, and the number of species was more verified in the Maeri region than the Mulgum region.

• Journal of Microbiology and Biotechnology
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• v.31 no.3
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• pp.368-379
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• 2021

Two virulence factors of Helicobacter pylori, cagA and vacA, have been known to play a role in the development of severe gastric symptoms. However, they are not always associated with peptic ulcer or gastric cancer. To predict the disease outcome more accurately, it is necessary to understand the risk of severe symptoms linked to other virulence factors. Several other virulence factors of H. pylori have also been reported to be associated with disease outcomes, although there are many controversial descriptions. H. pylori isolates from Koreans may be useful in evaluating the relevance of other virulence factors to clinical symptoms of gastric diseases because the majority of Koreans are infected by toxigenic strains of H. pylori bearing cagA and vacA. In this study, a total of 116 H. pylori strains from Korean patients with chronic gastritis, peptic ulcers, and gastric cancers were genotyped. The presence of virulence factors vacAs1c, alpA, babA2, hopZ, and the extremely strong vacuolating toxin was found to contribute significantly to the development of severe gastric symptoms. The genotype combination vacAs1c/alpA/babA2 was the most predictable determinant for the development of severe symptoms, and the presence of babA2 was found to be the most critical factor. This study provides important information on the virulence factors that contribute to the development of severe gastric symptoms and will assist in predicting clinical disease outcomes due to H. pylori infection.

• Research in Plant Disease
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• v.24 no.4
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• pp.308-312
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• 2018

We analyzed rice sample with scab (collected in 2017) for fungal occurrence and found that frequency of Fusarium spp. was the highest among fungal genera. Within Fusarium, Fusarium asiaticum-nivalenol type dominated as 79%. Among mycotoxins, zearalenone was the highest toxin detected (1117 ng/g), followed by deoxynivalenol (163 ng/g), 15-acetyl deoxynivalenol (155 ng/g), nivalenol (110 ng/g). Analysis of mycotoxin levels in scabby and healthy grains (collected in 2015) revealed that both grain samples were contaminated with zearalenone. However, level difference of zearalenone between the samples was over 5 times as the scabby samples were 1400-2370 ng/g, while healthy ones were 240-430 ng/g. This result indicates that scabby grains should be removed when harvest to reduce zearalenone contamination in rice.

• The Korean Journal of Mycology
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• v.43 no.3
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• pp.149-157
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• 2015

We examined taxonomic characteristics and safety of eight Nuruk molds that are widely used for making soybean paste, soy sauce and alcoholic beverages in Korea. HK1 from Hakyeong Fermentation Co., SW101 from Suwon Fermentation Co., CF1001, CF1002, CF1003 from Chungmoo Fermaentation Co. and KACC 93210 are yellow-Nuruk molds, and SW201 from Suwon Fermentation Co. and CF1005 from Chungmoo Fermentation Co. are white-Nuruk molds. Six strains of yellow-Nuruk molds were identified as Aspergillus oryzae. HK1, SW101, CF1001 and CF1003 of yellow-Nuruk molds have middle length of stipes ($711{\sim}1,121{\mu}m$), and CF1003 (for sake) produced less conidia and more hyphae than HK1, SW101 and CF1001 (for soybean paste). CF 1002 used for soy sauce has shorter stipes ($543{\mu}m$) and is clustered into IBLB-group based on omtA gene analysis although the other yellow-Nuruk molds are clustered into ICAo group. KACC 93210 isolated from traditional Korean Meju has very short stipes (average $270{\mu}m$), and showed velvety colonies although the others showed floccose colonies. The strain has different DNA sequences of omtA gene from other strains in NCBI GenBank as well as strains used in Korea, suggesting that it is unique from other strains published. SW201 and CF1005 of white-Nuruk molds were identified as Aspergillus luchuensis or A. luchuensis mut. Kawachii that is known as safe, non-toxigenic fungus. The six strains of yellow-Nuruk molds did not produce mycotoxins including aflatoxin, cyclopiazonic acid, and sterigmatocystin. Therefore, eight strains of Nuruk molds used for making soy sauce, soybean paste and alcoholic beverages in Korea were proved to be safe in this study.

• Research in Plant Disease
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• v.17 no.3
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• pp.272-279
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• 2011

Fusarium species are worldwide causal agents of Fusarium head blight (FHB) in cereals such as barley and wheat. Their toxigenic potential is a health risk for both humans and animals. To survey the natural occurrence of FHB and mycotoxins produced by Fusarium, total 126 barley or wheat grains grown in 2009-2010 season in Korea were collected. The incidence of FHB was 30.7% in silage barley, 26.9% in wheat, 20.7% in naked barley, 19.4% in malting barley, 16.4% in unhulled barley. Overall FHB incidence of barley and wheat in 2010 was 23.0% and 10% higher than that of 2009. The incidences and level of deoxynivalenol (DON), nivalenol (NIV), and zearalenone (ZEA) were 34%, 0.89 mg/kg, 84.9%, 1.86 mg/kg, and 10.3%, 0.06 mg/kg respectively. The both levels and incidences of NIV were found to be highest in barley, whereas the level of DON was found to be highest in wheat. Incidences of DON and NIV and the level of NIV in the samples from southern regions of Korea were higher than those from central region, whereas the level of DON from central region was higher than that from southern regions. This is the first paper demonstrating regional difference in natural occurrence of DON and NIV in wheat and barley.