Aktuğ Şahika GÖNÜL, A. Kemal SEÇKİN, Halil TOSUN

Acid adaptation effect on survival of Escherichia coli 0157:H7 in fermented milk products

Bu çalışmada sinbiyotik yoğurt, set tipi yogurt, süzme yoğurt ve kefirde, aside adapte edilen ve aside adapte edilmeyen Escherichia coli0157: H7 hücrelerinin gelişimleri incelenmiştir. Aside adapte edilen hücreler ve kontrol hücreleri sinbiyotik ve set tipi yoğurt örneklerine fermantasyondan önce ve sonra olmak üzere iki farklı aşamada ilave edilmiştir. Örneklere inokule edilen E. coli 0157:H7'nin canlılığı 4 T'de depolama sürecinde saptanmıştır. Kefir ve süzme yoğurtta, aside adaptasyon E. coii 0157: H7'nin canlılığını artırmıştır. Set tipi yoğurtta ise fermantasyon aşamasında ilave edilen örneklerde aside adaptasyon E. coli 0157: H7nın canlılığını artırmıştır. Bununla birlikte fermantasyondan önce inokule edilen örneklerde aside adaptasyonun £ coli 0157: H7'nin canlılığına etkisi olmamıştır. Bu sonuçlar aside adaptasyonun, £ coli 0157: H7nin fermente sıit ürünlerinde canlı kalmasına olanak sağlayan önemli bir mekanizma olduğunu ifade eden teorileri desteklemektedir.

Aside adaptasyonunun Escherichia coli 0157:H7' nin fermenta süt ürünlerinde canlılığına etkisi

The growth and survival of acid-adapted and nonadapted Escherichia coli 0157:H7 were determined in strained, set-type, and synbiotic yoghurt and kefir. Acid-adapted or nonadapted E. ccrf/0157:H7 were inoculated into the synbiotic and set-type yoghurt before and after the fermentation process. Survival of the inoculated E. co/ı 0157:H7 in these products was examined during storage at 4 X. Acid adaptation enhanced the survival of £ coli 0157:1-17 in kefir and strained yoghurt Acid adaptation also enhanced the survival of E coli 0!57:H7 in set-type yoghurt which was inoculated after the fermentation process; however, acid-adapted cell inoculation before fermentation did not enhance survival. These observations support the theory that acid adaptation is an important survival mechanism enabling £ coil 0157: H7 to persist in fermented dairy products.

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