개선된 회수율을 갖는 새로운 대장균 선택배지(nESM)의 개발 = Development of New E. coli Selective Media (nESM) Having Improved Recovery Rate

다국어 초록 (Multilingual Abstract)

This study is to develop a selective medium which grows more E. coli compared to commercialized or established E. coli growth media, by using a recovery rate depending on the composition of E. coli growth medium. X-gluc (5-bromo-4-chloro-3-indolyl-beta-D-glucuronic acid) was selected as the E. coli-specific chromogenic substrate and then the specificity and the sensitivity for the reference strains and the food-isolated strains were evaluated. Carbon sources include a total of four ingredients, such as glucose, sucrose, galactose and lactose, nitrogen sources include a total of nine ingredients, such as yeast extract, casein enzymic hydrolysate, meat extract, proteose peptone, soya peptone, trypton, beef extract, casein peptone and special peptone, buffering agents include a total of five ingredients, such as pyruvate and sodium chloride, sodium citrate dihydrate, potassium phosphate monobasic and potassium phosphate dibasic. and gram-positive inhibitors include a total of four ingredients types, such as sodium dodesyl sulfate, oxgall, sodium deoxycholate and bile salts. It was analyzed the recovery rate of E. coli and S. aureus (ATCC 25923) spreaded after culturing for 16 hours depending on each ingredient. In the result using One-way ANOVA and Duncan test for statistical analysis, the medium containing glucose, beef extract and sodium chloride, and sodium deoxycholate for inhibiting growth of gram-positive bacteria was the greatest for the proliferation of E. coli, and also the colony size was significantly different depending on medium ingredients. Furthermore, the substrate, X-gluc, showed the sensitivity and specificity higher than 99% for E. coli compared to non-E. coli bacteria. Further medium performance tests of more isolated strains and comparative studies with established selective media will be performed to investigate the feasibility of the practical use of the E. coli medium composition we studied here.