• Journal of Food Hygiene and Safety
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• v.26 no.4
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• pp.296-301
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• 2011

This study was to evaluate the growth potential of E. coli O157:H7 in lettuce leaf extracts and on lettuce leaf surface at various temperatures. The pathogen can survive and multiply in the extracts and leaf surface of lettuce. The population of E. coli O157:H7 in the lettuce extracts reached to 4.79 log CFU/mL at $37^{\circ}C$. The multiplication of pathogen in lettuce extracts initiated within 10 hours of inoculation over $15^{\circ}C$ conditions. And it can survive in the lettuce leaf extracts at $4^{\circ}C$ for 100 hours at least. And this pathogen can multiply on lettuce leaf surface and the population of pathogen on the lettuce leaf surface increased to 1.82 log CFU/g at $25^{\circ}C$. At $37^{\circ}C$, the pathogen density increased to 1.53 CFU/g within 3 days after inoculation. At all temperature, irrespective of the inoculation level, similar trends in growth of E. coli O157:H7 were observed. These results emphasize the growth potential of E. coli O157:H7 in lettuce leaf extract and on lettuce leaf surface. To reduce the risk of outbreak, it is important to maintain the cold chain system during storage before the consumption.

• Journal of Food Hygiene and Safety
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• v.20 no.1
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• pp.48-52
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• 2005

This study was investigated to determine the antimicrobial activity of ethanol extract of green tea, and of solvent fractionated ethanol extract on Escherichia coli O157:H7. MIC value of ethanol extracts and solvent fractionated ethanol extract (hexane, ethyl-acetate, chloroform and water) were $2000{\mu}g/ml,\;0,\;500{\mu}g/ml,\;2000{\mu}g/ml,\;1000{\mu}g/ml$, respectively. The antimicrobial activity of ethyl acetate fraction against E. coli O157 :H7 ranged from $250-2000{\mu}g/disk$. The antimicrobial activity was significantly increased as concentration dependent. When E. coli O157:H7 was pH-adjusted TSB containing $1000{\mu}g/ml$ ethyl acetate, E. coli O157:H7 was significantly inhibited at initial pH of 10, whereas the pathogen grew well in the presence of pH 4.5-pH 9. The inhibitory effect of the ethyl acetate fraction on the growth of E. coli O157 :H7 was investigated. Growth of both strain in the tested conditions were rapidly occurred up to 12 h, but no growth was occurred in the presence of $250-1000{\mu}g/mL$ of ethyl acetate fraction for 72 h.

• Journal of Life Science
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• v.18 no.3
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• pp.395-402
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• 2008

Level of microbial contamination was examined in four fish farms of Jeju east coast for sanitary indication of bacterial contamination such as heterotrophic bacteria, Escherichia coli O157:H7, Salmonella spp., Vibrio parahaemolyticus, Staphylococcus aureus, Bacillus cereus and total coliforms. The samples were collected and investigated from June to October in 2007. Bacterial species of S. aureus, B. cereus and Salmonella spp. were frequently detected from the seawater of above fish farms. Salmonella spp., S. aureus, B. cereus were detected in the range of $0{\sim}4.3{\times}l0^3,\;0{\sim}2.7{\times}l0^4,\;0{\sim}7.6{\times}l0^3$ CFU/ml, respectively, from the fish feed used in all four selected farms. Additionally, Salmonella spp., S. aureus, B. cereus were detected in oliver flounder (Paralichthys olivaceus) of these farms, however total coliforms and E. coli O157:H7 were not detected during our experimental period. For the production of microbiologically safe and healthy oliver flounder, proper quality control of feed, sanitation programs, and continuous monitoring of microorganism are essential practices, which required to include in the farm management system.