Kefir, which is a fermented milk product that was recently introduced in Japan is becaming available for widespread consumption. Because there is the effect of controlling the growth of food poisoning bacteria in acid milk, it is expected that the growth of E. coli O157: H7 in kefir can be similarly controlled. When E. coli ATCC or E. coli O157: H7 was cultivated in a pH-neutral condition, the growth of the bacterium was not influenced at all regardless of the presence of kefir. On the other hand, when E. coil ATCC or E. coli O157: H7 was cultivated in pH-acid condition, the growth of these was markedly inhibited. The growth of E. coli ATCC of 109 cfu/ml or E. coli O157: H7 of 107 cfu/ml to which kefir of pH 4 was added was especially completely inhibited in a short time. These results suggested that an antibacterial substance to the growth of E. coli ATCC or E. coli O157: H7 was existed in kefir.
The purpose of this study was to evaluate the isolated media of Salmonella and to determine the usefulness of practices used for isolation of Salmonella from food and feed. ES Salmonella medium was based on the use of X-GAL enzyme, and compared to other isolated media for detection of Salmonella. A total of 47 Salmonella and various gramnegative and gram-positive bacteria were used for evaluation of the media with testing by the method of Miles and Misra. Salmonella Enteritidis was put in liquid eggs, broilers and human feces to compare detection of Salmonella Enteritidis, and the contamination of Salmonella was examined for isolation from those by the selective medium. ES Salmonella medium was as effective or better than other commercial selective media such as DHL, MLCB, BG and SMID media for isolation of Salmonella. ES Salmonella medium was therefore considered effective for isolation of Salmonella from food and feed, but not from the samples of human feces.