GROWTH OF YERSINIA-ENTEROCOLITICA AND AEROMONAS-HYDROPHILA IN ACIDOPHILUS YOGURT

Survival and growth of Yersinia enterocolitica and Aeromonas hydrophil a in acidophilus yoghurt and control yoghurt were investigated. These two types of yoghurt containing the pathogenic bacteria were stored at 4 +/- 1-degree-C for 26 days. Numbers of Y. enterocolitica, A. hydrop hila and Lactobacillus acidophilus, as well as pH values of yoghurt sa mples were determined at appropriate intervals. While the numbers of v iable A. hydrophila in acidophilus and control yoghurts were markedly reduced after one day's storage, and non existent after five days, Y. enterocolitica survived until the end of storage. During storage, diff erences were obtained between the acidophilus yoghurt and the control yoghurt in the counts of both pathogenic bacteria suggesting that inhi bition due to L. acidophilus, in addition to the acidity of the yoghur t, contributed to the decreased viability of Y. enterocolitica and A. hydrophila. Numbers of L. acidophilus did not decrease during storage.