• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.2043-2048
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• 2015

Bacillus thuringiensis microbial insecticide products have been applied worldwide. Although a few cases of B. thuringiensis foodborne illness have been reported, little is known about the toxigenic properties of B. thuringiensis isolates. The aims of this study were to estimate the pathogenic potential of B. thuringiensis selected from microbial insecticide products, based on its possession of toxin genes and production of enterotoxins. Fifty-two B. thuringiensis strains selected from four kinds of microbial insecticide products were analyzed. PCR assay for detection of toxin genes and immunoassay for detection of enterotoxins were performed. The hemolysin BL complex as a major enterotoxin was produced by 17 (32.7%), whereas the non-hemolytic enterotoxin complex was detected in 1 (1.9%) of 52 B. thuringiensis strains. However, cytK, entFM, and ces genes were not detected in any of the tested B. thuringiensis strains. The potential risk of food poisoning by B. thuringiensis along with concerns over B. thuringiensis microbial insecticide products has gained attention recently. Thus, microbial insecticide products based on B. thuringiensis should be carefully controlled.

• 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.

• Journal of the Korean Dietetic Association
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• v.13 no.2
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• pp.169-182
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• 2007

We investigated elementary school students' knowledge, behavior, experience and preference of education method related to food safety in order to provide basic information for food safety educational program. A survey study was conducted with 569, fourth and sixth grade students, from two schools in Seoul and Ulsan. Students were asked thirty-two questions regarding food safety knowledge, behavior and experiences as well as their attitude to food safety class and preference for teaching method. The data was analyzed for the frequency analysis, t-test, chi-square test, one-way ANOVA and Pearson correlation using the SPSS/Windows. Results indicated that 91.9 percent of the respondents did not know what unsanitary food is. 67 percent of the respondents did not know the proper method of hand washing. Although the students' level of knowledge and behavior associated with food safety was low, there was meaningful correlation(r =.184, p<.01) between knowledge and behavior. Surprisingly, students in higher grade did not demonstrate an exceeding food safety knowledge and behavior. More than 50 percent of the subjects did not have food safety education either at home or school. 60 percent of the respondents interested in food safety and the majority recognized that a food safety education is needed. Students want to learn about unsanitary food(34.1%), foodborne illness(29.7%), food selection and storage method(21.3%), and personal hygiene(11.2%) through game, role play, and practice in real situation. These results suggest that development of food safety education program is needed through the elementary school year and the education program must include fun activities in which students can participate.

• Journal of the Korean Dietetic Association
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• v.10 no.4
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• pp.381-389
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• 2004

The purpose of this study was to investigate effectiveness of sanitization on raw vegetables not heated in foodservice operations. Microbiological examinations of food materials and cooked food with leek Gukgalli were performed in 2 HACCP-implemented foodservices (A and B) appointed by Food and Drug Administrations, and in 2 other foodservices (C and D) not implemented HACCP. 'Washing and sanitizing raw vegetables' were monitored as CCP at A and B foodservices but only washing has been done in pre-preparation at C and D foodservices. Aerobic plate counts of received leek in A and B foodservices were above $10^7$ CFU/g indicating very poor microbiological quality. After sanitization treatment (soaking for 5 minutes in chlorine water: chlorine density 50〜100 ppm), its aerobic plate counts decreased to 7.06×$10^5$ CFU/g (A foodservice) and 4.31×$10^5$ CFU/g (B foodservice), coliform and faecal coliform were not detected. With this result, the effect of microbial reduction by sanitizer was conformed. But, the conditions of leek were still not acceptable by microbiological standards for ready-to-eat foods. After three more times of rinse has been done, the microbial conditions of leek became acceptable. In C and D foodservices, aerobic plate counts of leek showed decreasing trends by 2〜4 times of washings but microbiological quality of leek after pre-preparation were unacceptable by microbiological standards for ready-to-eat foods (C foodservice: 3.58×$10^5$ CFU/g, D foodservice: 1.29×$10^9$ CFU/g). For the prevention of foodborne illness, sanitizing raw vegetables should be performed during pre-preparation of non-heated foods.

• Journal of Environmental Health Sciences
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• v.28 no.2
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• pp.161-171
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• 2002

The number of food establishments selling raw and convenience foods are increasing in Korea, and people enjoy purchasing and eating foods at these shops. However, there are only a few reports on the temperature control of the refrigerators and freezers at retail food shops. This study was performed to investigate the temperature control of refrigerators and freezers in retail food shops in Daegu. The survey was carried out from July 20 to August 30 in 2001. The trained surveyors visited the twenty retail food shops (four department stores, eight marts/supermarkets and eight convenience stores) in the 8 major areas of Daegu and inspected the temperature control of 48 refrigerators for dairy products, fruits & vegetables, and rolled rice & sandwiches, and 52 freezers for ice cream & sherbet, frozen food, and frozen fish. The percentage of the refrigerators, and freezers with unsafe temperatures higher than the recommended safe temperature (10℃ for refrigerators, and -18℃ for freezers) was 42%; 45.8% in refrigerators; 38.5% in freezers. On an average, the bigger the size of the shop, the better than the other freezers. On the other hand, the temperature control of refrigerator for fruits & vegetables was the worst because they were usually open. Actual temperatures in the refrigerators and freezers were found to be significantly higher than the reading on the thermometers attached to the refrigerators and freezers(p<0.05). These results indicate that temperature control of refrigerators and freezers at retail food shops should be monitored several times each day, and should have strict inspection. There should be more detailed legal standard and specification for temperature control of refrigerators and freezers at retail food shops to prevent foodborne illness from unsafely stored food.

• Korean Journal of Community Nutrition
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• v.12 no.3
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• pp.310-321
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• 2007

Effective and systematic sanitation management programs are necessary to prevent foodborne disease outbreaks in school foodservice operations. The purpose of this study was to identify the elements to improve in order to ensure the safety of school food service by evaluating sanitation management practices implemented under HACCP-based programs. The survey was designed to assess the level of hygiene practices of school food service by using an inspection checklist of food hygiene and safety. Fifty-four school foodservice establishments considered as poor sanitation practice groups from two year inspections by Seoul Metropolitan Office of Education were surveyed from September to December in 2005. Inspection checklists consisted of seven categories with 50 checkpoints; facilities and equipment management, personal hygiene, ingredient control, process control, environmental sanitation management, HACCP system and safety management. Surveyed schools scored $68.0{\pm}12.42$ points out of 100 on average. The average score (% of compliance) of each field was 10.7/20 (53.3%) for facilities and equipment management, 7.4/11 (67.2%) for personal hygiene, 7.4/11 (74.1%) for ingredient control, 22.4/32 (69.8%) for process control, 8.9/12 (73.8%) for environmental sanitation management, 4.2/7 (59.7%) for HACCP systems management, and 7.2/8 (89.7%) for safety management, respectively. The field to be improved first was the sanitation control of facilities and equipment. The elements to improve this category were unprofessional consultation for kitchen layout, improper compartment of the kitchen area, lacks of pest control, inadequate water supply, poor ventilation system, and insufficient hand-washing facilities. To elevate the overall performance level of sanitation management, prerequisite programs prior to HACCP plan implementation should be stressed on the school officials, specifically principals, for the integration of the system.

• Journal of the East Asian Society of Dietary Life
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• v.25 no.4
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• pp.691-702
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• 2015

This study examined the levels of risk perception of food risk elements by adopting a psychometric paradigm and analyzed factors affecting concerns about food risk elements to obtain basic materials for food safety policy. The data were collected from 296 housewives in Daegu, Korea, by a self-administered questionnaire. Frequency distributions, Pearson's correlation coefficient analysis, factor analysis, Cronbach's ${alpha}$, and multiple regression analyses were conducted by SPSS 21.0. The mean level of concern for food safety was 3.75/5.00 points, and the mean percentage of correct answers about heavy metal contamination was highest among food risk elements. The respondents perceived radioactive contaminated foods, GM foods, and endocrine disruptors as a new, delayed, scientifically unknown, involuntary, serious, and uncontrollable risk in risk perception. According to the result of factor analysis for risk perception, two factors such as non-controllability and dread were categorized. In the risk perception map, radioactive contaminated foods and GM foods were considered as an uncontrollable and dreaded risk, heavy metal contamination, endocrine disruptors, and pesticide residues as a controllable and dreaded risk, and foodborne illness and food additives as a controllable and less dreaded risk. On the other hand, the levels of concerns about food risk elements were higher in order of radioactive contaminated foods, GM foods, and endocrine disruptors. The results of multiple regression analysis showed that age, concern for food safety, percentage of correct answers about food risk elements, non-controllability, and dread influenced the concerns about food risk elements. These results imply that food safety policies should consider differences in consumer's risk perception of food risk elements.

• Journal of Microbiology and Biotechnology
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• v.28 no.8
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• pp.1233-1246
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• 2018

Vibrio parahaemolyticus contamination causes serious foodborne illness and has become a global health problem. As a disinfectant, aqueous ozone can effectively kill a number of bacteria, viruses, parasites, and other microorganisms. In this study, three factors, namely, the aqueous ozone concentration, the exposure time, and the bacterial density, were analyzed by response surface methodology, and the aqueous ozone concentration was the most influential factor in the sterilization ratio. Under low aqueous ozone concentrations (less than 0.125 mg/l), the bacterial cell membranes remained intact, and the ozone was detoxified by intracellular antioxidant enzymes (e.g., superoxide dismutase and catalase). Under high aqueous ozone concentrations (more than 1 mg/l), cell membranes were damaged by the degree of peripheral electronegativity at the cell surface and the concentration of lactate dehydrogenase released into the extracellular space, and the ultrastructures of the cells were confirmed by transmission electron microscopy. Aqueous ozone penetrated the cells through leaking membranes, inactivated the enzymes, inhibited almost all the genes, and degraded the genetic materials of gDNA and total RNA, which eventually led to cell death.

• Food Science of Animal Resources
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• v.39 no.1
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• pp.84-92
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• 2019

Listeria monocytogenes is a major cause of serious foodborne illness in the dairy foods. Although Caenorhabditis elegans model is well established as a virulence model of pathogenic bacteria, its application on L. monocytogenes is critically unclear. The objective of this study was to carry out an evaluation of L. monocytogenes toxicity using C. elegans nematode as a simple host model. We found that C. elegans nematodes have high susceptibility to L. monocytogenes infection, as a consequence of accumulation of bacteria in the worms' intestine. However, L. innocua, which is known to be non-toxic, is not accumulate in the intestine of worms and is not toxic similarly to Escherichia coli OP50 known as the normal feed source of C. elegans. Importantly, immune-associated genes of C. elegans were intensely upregulated more than 3.0-fold when they exposed to L. monocytogenes. In conclusion, we established that C. elegans is an effective model for studying the toxicity of L. monocytogenes and we anticipate that this system will result in the discovery of many potential anti-listeria agents for dairy foods.

• Korean Journal of Food Science and Technology
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• v.53 no.3
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• pp.334-343
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• 2021

Various vegetables, including cucumbers, have a high probability of foodborne illness because they are usually eaten raw. In this study, we analyzed the 16S rRNA gene sequences of the cucumber (Cucumis sativus L.) microbiota. The diversity indices of cucumber cultivated in May were higher than in cucumber cultivated in November. At the phylum level, Proteobacteria, Firmicutes, and Actinobacteria were predominant. The classes generally comprised Gammaproteobacteria, Bacilli, Alphaproteobacteria, and Actinobacteria. At the genus level, the proportions of Aureimonas, Escherichia, and Microbacterium in samples from May were relatively high, whereas Enterococcus, Pseudomonas, and Rhizobium accounted for a higher proportion in samples from November. Moreover, it is noteworthy that potential pathogenic genera such as Acinetobacter, Aerococcus, Aureimonas, Enterobacter, Enterococcus, Escherichia, Pantoea, Pseudomonas, and Staphylococcus were detected. Although further studies on the characteristics of potential pathogens are required, our results can be used to improve the food safety of vegetables.