The change in heat inactivation of Escherichia coli O۱۵۷:H۷ after entering into the viable but non-culturable state in salted fish, Hypophthalmichthys molitrix
- سال انتشار: 1400
- محل انتشار: مجله علوم زیستی خاورمیانه، دوره: 19، شماره: 4
- کد COI اختصاصی: JR_CJES-19-4_003
- زبان مقاله: انگلیسی
- تعداد مشاهده: 197
نویسندگان
Department of Seafood Science, Faculty of Marine Sciences, Tarbiat Modares University, Noor, Iran
Department of Seafood Science, Faculty of Marine Sciences, Tarbiat Modares University, Noor, Iran
Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Fisheries Department, Agriculture and Natural Resource University of Gorgan, Gorgan, Iran
چکیده
Many species of non-sporulating bacteria including Escherichia coli can enter into a viable but non-culturable (VBNC) state under stress conditions. In this study, the change in thermal resistance of E. coli O۱۵۷:H۷ after entering into the VBNC state in salted silver carp, Hypophthalmichthys molitrix, was investigated. E. coli O۱۵۷:H۷ was inoculated on the fish control group (TF) and on those fish with ۳۰% NaCl (TF + ۳۰% NaCl) at room temperature. Culturability of bacteria was determined using routine culture and colony counting on Sorbitol MacConkey agar. When bacteria were non-cultivable, the RT-PCR of ۱۶S rRNA gene (including direct extraction and purification of RNA, DNase I treatment for removing DNA contamination, cDNA synthesis and electrophoresis of PCR products of cDNA) was used to detect VBNC E. coli O۱۵۷:H۷. Also, cultivable and VBNC E. coli O۱۵۷:H۷ were individually heat-treated at ۵۵, ۶۲ and ۷۰ °C for ۵ min. The samples were cooled and after ۲۴ h, the thermal resistance of bacteria was determined through viability detection using RT-PCR of ۱۶S rRNA gene. The culturability of bacteria was kept in fish treatment but they were non-cultivable in fish under ۳۰% NaCl after ۵ days. The positive expression of ۱۶S rRNA in all studied treatments indicated the entering of E. coli O۱۵۷:H۷ into the VBNC state in fish treatment under ۳۰% NaCl. Moreover, the RT-PCR of ۱۶S rRNA gene showed that only VBNC forms of E. coli O۱۵۷:H۷ showed viability at ۶۲ °C for ۵ min which indicated the increased resistant of VBNC bacteria to the thermal inactivation. The ability of E. coli O۱۵۷:H۷ to enter into VBNC state in salted fish and also the increase of its thermal resistance suggest that VBNC E. coli O۱۵۷: H۷ can be considered as critical threat to public health and food safety.کلیدواژه ها
Escherichia coli O۱۵۷:H۷, VBNC state, Thermal resistanceاطلاعات بیشتر در مورد COI
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