• Korean Journal of Microbiology
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• v.48 no.1
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• pp.22-28
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• 2012

Vibrio parahaemolyticus is one of the major agents responsible for food poisoning during summer in Korea, which is transmitted via seawater or seafoods. Recently, distribution of the bacteria in the marine environment has been increased due to global warming. Great concern also has been raised regarding public hygiene as well as marine culture by the emergence of pathogens with antibiotic resistance. Therefore, distribution of V. parahaemolyticus and antibiotic resistance of the isolates were monitored in 7 coastal areas of Kyonggi Province and Incheon by sampling seawater, fishes and clams monthly. V. parahaemolyticus was detected from 47.7% of 966 samples (seawater 61.9%, seafoods 41.8%) analyzed using $CHROMagar^{TM}$ and TCBS agar plates as well as multiplex PCR. Among 13 antibiotics tested, resistance to vancomycin and ampicillin was observed in 97.3% and 87.3% of the isolates, respectively, and the ratios of them resistant to cephalothin (48.8%) and rifampin (46.1%) were also high. The isolates were most highly sensitive to chloramphenicol (91.7%) and trimethoprim-sulfamethoxazole (91.8%). The ratio of sensitivity for other antibiotics was also high in the descending order of gentamycin (82.3%), tobramycin (74.8%), nalidixic acid (71.6%), tetracyclin (69.4%), cefotaxime (63.0%). About 69% of the isolates showed multiple drug resistance toward 3 antibiotics including vancomycin and ampicillin. Two of them exhibited resistance for 11 antibiotics used in this study. Plasmid profile analysis of the isolates with antibiotic resistance revealed that 55.1% of them retained plasmids of 24 different types. However, no clear inter-relationship between the resistance and the plasmid profile has been observed.

• Korean Journal of Microbiology
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• v.50 no.1
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• pp.27-32
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• 2014

Autophagy is one of the lysosomal degradation pathways to maintain cellular homeostasis. The damaged proteins or organelles are uptaken through extra- and intra-cellular stress, starvation and infected pathogens, subsequently, autophagosomes are fused with lysosomes to break down the molecules. Salmonella enterica serovar Typhimurium (S. Typhimurium), intracellular bacteria, cause acute gastroenteritis and food poisoning. Given that autophagy induced by S. Typhimurium plays an important role in the cells to control the infection, we identify whether the induction of autophagy with rapamycin, chemical inducer of autophagy, before infection regulates S. Typhimurium infection. After treatment of rapamycin or 3-methyladenine (3-MA), autophagy inhibitor, RAW264.7 cells were infected with S. Typhimurium. Pretretment of rapamycin decreased the growth rate of S. Typhimurium in the cells; otherwise, pretreatment of 3-MA increased the growth rate of S. Typhimurium. The expression of autophagy-related genes was significantly increased in the S. Typhimurium-infected cells pretreated with rapamycin. To examine whether induced autophagy by rapamycin control the infection with increase the production of reactive oxygen species (ROS) and nitric oxide (NO), antibacterial radical substrates were measured in infected cells followed by the treatment with either rapamycin or 3-MA. NO production increased in RAW264.7 cells; otherwise, ROS production remained unchanged during the infection. These findings suggest that inducing autophagy with rapamycin reveals antimicrobial activity as producing NO against S. Typhimurium infection in mouse macrophages.

• Journal of Life Science
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• v.15 no.4 s.71
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• pp.647-651
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• 2005

The major causative bacteria of food poisoning were Salmonella spp. $(35.6\%)$, Staphylococcus aureus $(11.3\%)$ and Vibrio parahaemolyticus $(3.2\%)$ in our country. In this study we attempted isolation of S. aureus from stools of patients with diarrhea. Sixty-four strains $(9.1\%)$ were isolated from 704 the stools of patients with diarrhea. The enterotoxin was detected from 29 isolates $(45.3\%)$: 24 isolates $(37.5\%)$, 3 isolates $(4.7\%)$ and 2 isolates $(3.1\%)$ were A, B and C type, respectively. In the antibiotic susceptibility, 63 isolates $(98.4\%)$ were resistant to penicillin, 60 isolates $(93.8\%)$ to ampicillin, 35 isolates $(54.7\%)$ to erythromycin, 32 isolates $(50.0\%)$ to gentamycin, 22 isolates $(34.4\%)$ to tetracycline and 20 isolates $(31.3\%)$ to oxacillin. All of S. aureus isolates were susceptible to chloramphenicol and vancomycin, 20 isolates $(31.3\%)$ were methicillin-resistance S. aureus (MRSA). MRSA isolation rate was higher in male $(35.7\%)$ than female $(26.3\%)$. With the exception of two isolates which were resistant only to penicillin, sixty-one isolates were multiple antibiotic resistance.

• Journal of agriculture & life science
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• v.46 no.3
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• pp.97-108
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• 2012

Physical, chemical and biological hazards of strawberry farms at the cultivation stage were analyzed to establish the GAP(Good Agricultural Practice) system. Samples were collected from the plants, cultivation environments(water, soil and air), and personal hygiene (hand, glove, and clothes) of three strawberry farms(A, B, and C) and were tested to analyze physical, chemical (heavy metals and pesticide residues), and biological(sanitary indications and foodborne pathogens) hazards. Physical hazards such as insects and pieces of metal and glass were found in the strawberry farms and can be potential bow for strawberry products. Heavy metal and pesticide residue as chemical hazards were detected at levels lower than the regulation limit. In case of biological hazards, total bacteria and coliform were detected at the levels of 1.6~7.3 and 1.3~5.6 log CFU/g, leaf, mL, hand or $100cm^2$. However, Escherichia coli was not detected in all samples. Bacillus cereus and Staphylococuus aureus were detected at levels of ${\leq}$ 1.1~6.1 log CFU and 4.7~5.4 log CFU/g, mL, hand or $100cm^2$, whereas Listeria monocytogenes, E. coli O157 and Salmonella spp. were not detected in all samples. This study demonstrates that various harzards were in strawberry farms at the growing stage. Therefore proper management such as GAP is needed to prevent the occurrence of food poisoning associated with the hazards revealed in this study.

• Journal of Food Hygiene and Safety
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• v.13 no.4
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• pp.441-447
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• 1998

This study was performed to investigate the changes of amount of S. typhimurium during cooking processes using pork and japchae (a Korean food which is made from meat, vegetables and noodles), and to support a practical application to develop a hazard analysis critical control point (HACCP) model. The pork was purchased in a retail shop, cut ($0.5\;cm\;{\times}\;10\;cm\;{\times}\;10\;cm$, 25 g), tested for Salmonella contamination (results: negative), inoculated with S. typhimurium ($10^{7}\;CFU/g$), then treated in various conditions related to cooking. Mter thawing for 24 hours in various conditions, the number of S. typhimurium was increased to $10^{10}\;CFU/g$ at a refrigerated temperature ($4~10^{\circ}C$), and to $10^{21}\;CFU/g$ at room temperature ($22~29^{\circ}C$). Mter thawing in a microwave oven for 40 seconds, the number of S. typhimurium increased to $10^{8}\;CFU/g$. During the thawing period, the number of S. typhimurium increased over time. At the refrigerated temperature, the number of the bacteria was $10^{10}\;CFU/g$ after 24 hours, $10^{13}\;CFU/g$ after 48 hours, and $10^{20}\;CFU/g$ after 72 hours. At room temperature the number of bacteria reached $10^{11}\;CFU/g$ in 2 hours, $10^{15}\;CFU/g$ in 4 hours, $10^{16}\;CFU/g$ in 8 hours, $10^{18}\;CFU/g$ in 12 hours, and $10^{21}\;CFU/g$ in 24 hours. Mter cooking in a frying pan (150{\pm}7^{\circ}C$) for 3 minutes, the bacterial count was $10^{16}\;CFU/g$. After cooking in hot water for 20 minutes, the bacterial count was $10^{7}\;CFU/g\;at\;60^{\circ}C,\;10^{6}\;CFU/g\;at\;63^{\circ}C,\;and\;10^{4}\;CFU/g\;at\;65^{\circ}C$. The fried pork was mixed with cooked vegetables, noodles, sesame oil, sesame seeds, and seasonings to make Korean japchae. This process took $10{\pm}2$ minutes. The bacterial count in the japchae increased to $10^{7}\;CFU/g$ from the count of $10^{6}\;CFU/g$ of the fried pork before it was mixed with the other ingredients. These results indicate that the amount of S. typhimurium is effected by various different cooking processes. This study can suggest that pork should be cooked in water at over $65^{\circ}C$ for 20 minutes in order to prevent food poisoning, if the pork is contaminated with S. typhimurium. The presence of S. typhimurium in the raw pork is identified in an HA for japchae, and the primary CCP for japchae is inadequate cooking (cooking method and time/temperature). We need to standardize time-temperature-size and amount of pork in cooking japchae, because pork is usually cooked in ordinary frying pans when we make this food.

• Journal of agriculture & life science
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• v.44 no.2
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• pp.7-15
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• 2010

This study was conducted to investigate the bacteriological and physiological quality of seawater and surface sediments in Sacheon Bay of Korea from January to September in 2009. During the study period, the means of temperature was range from 5.3 to $24.9^{\circ}C$ (mean $17.7{\pm}0.4^{\circ}C$), transparency range from 1.4 to 2.5 m (mean $1.8{\pm}0.5m$), suspended solid ranged from 16.2 to 35.8 mg/L (mean $24.2{\pm}2.2mg/L$), chemical oxygen demand ranged from 1.42 to $3.29mgO_2/L$ (mean $2.06{\pm}0.55mgO_2/L$), dissolved oxygen ranged from 6.7 to 9.5mg/L (mean $7.9{\pm}0.6mg/L$), respectively. Seafood, if eaten raw, carries the risk of food poisoning. Seafood poisoning is often cause by pathogenic microorganism originating from fecal contamination, such as Salmonella sp., Shigella sp. and norovirus. Fecal coliforms are an important indicator of fecal contamination. Therefor, data on fecal coliform are very important for evaluating the safety of fisheries in coastal areas. So, we investigated the sanitary indicate bacteria. In this study, 56 sea water samples were collected from the Sacheon Bay, and total and fecal coliforms were compared and analyzed. The coliform group and fecal coliform MPN's of sea water in Sacehon Bay were ranged from <1.8~7,900 MPN/100mL (GM 214.7 MPN/100mL) and <1.8~330 MPN/100mL (GM 9.7 MPN/ 100mL), respectively. Total coliforms were detected in 75.0% of the samples and 76.2% of the total coliforms were fecal coliforms. During the study period, the means of water content, ignition loss, COD, and acid volatile sulfates in sediments in Sacheon Bay were $53.28{\pm}2.58%$, $9.38{\pm}0.42%$, $14.23{\pm}3.36mgO_2/g$, $0.09{\pm}0.07mgS/g$, respectively.

• Journal of Life Science
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• v.34 no.3
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• pp.191-198
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• 2024

To verify the nutritional value and safety of larvae fed with a soymilk residue-added food source, we compared and analyzed the nutritional components of and harmful substances in Tenebrio molitor larvae reared on wheat bran. Crude protein content based on dry weight was 1.2 times higher in the 10% soymilk residue-fed group (SR) (54.0%) than in the wheat bran-fed group (WB) (43.5%). Dietary fiber also tended to be 1.9 times more in the SR (4.9%) than the WB (2.5%). Among unsaturated fatty acids, the linoleic acid content was found to be 1.1-fold higher in the SR (32.9%) than in the WB (29.0%). Potassium, which was the most abundant among the macro minerals, was 1.1-fold more abundant in the WB (1,074.5 mg/100 g) than in the SR (1,014.0 mg/100 g). Among the micro minerals, zinc content was 1.2-fold higher in the SR (14.5 mg/100 g) than in the WB (11.9 mg/100 g). The results of the analysis of hazardous substances in the WB and SR revealed that the amount of heavy metals met the standards for heavy metals in edible insects, and food poisoning-inducing bacteria such as Escherichia coli and Salmonella spp. were not detected in all groups. These results indicate that mealworm larvae fed with 10% soymilk residue have abundant nutrients and are safe for intake. Thus, food sources with added soymilk residue has the potential to be used as feed ingredients.

• Journal of Food Hygiene and Safety
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• v.13 no.2
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• pp.143-148
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• 1998

The purpose of this study was to determine the kinetics of paralytic shellfish poison (PSP) destruction at various temperature. The toxic digestive gland homogenate of blue mussel (Mytilus edulis), PSP crude toxin, gonyautoxin group and saxitoxin group were heated at temperature ranging from 90 to $120^{\circ}C$, and then the toxicities were measured in samples heated for various time intervals. The rate constant (k) of the toxic digestive gland homogenate, PSP crude toxin, gonyautoxin group and saxitoxin group were $3.28{\times}10^{-2},\;1.20{\times}10^{-2},\;5.88{\times}10^{-2}\;and\;2.58{\times}10^{-2}\;at\;120^{\circ}C$, respectively. The decimal reduction time (D-value) of the toxic digestive gland homogenate, PSP crude toxin, gonyautoxin group and saxitoxin group were 70, 192, 39 and 89 at $120^{\circ}C$, respectively. These results indicate that PSP crude toxin is most heat-stable of 4 types of PSP toxins and PSP toxin are more heat-stable than food poisoning bacteria and spores. The retorting condition to reduce PSP toxicity below quarantine limit ($80\;\mu\textrm{g}/100\;g$ in Korea and America, 4 MU/g in Japan) could be calculated by rate constant. For example, the digestive gland homogenate having a initial toxicity of $200\;\mu\textrm{g}/100\;g$ could have toxicity below quarantine limit when heated at $90^{\circ}C$ for 129 min., $100^{\circ}C$ for 82 min., $110^{\circ}C$ for 48 min. and $120^{\circ}C$ for 28 min. These results suggest that commercial retorting condition ($115^{\circ}C$ for 70 min) in Korea is enough to reduce toxicity below quarantine limit from initial toxicity of $200\;\mu\textrm{g}/100\;g$. From these results, the quarantine limit of PSP-infested shellfish for canning can be level up to raw score of $200\;\mu\textrm{g}/100\;g$.