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Viable but non culturable state and expression of pathogenic genes of Escherichia coli O157:H7 in salted silver carp
Journal of Food Safety ( IF 1.9 ) Pub Date : 2020-08-17 , DOI: 10.1111/jfs.12843
Mohammad Khezri 1 , Masoud Rezaei 1 , Ashraf Mohabbati Mobarez 2 , Mehdi Zolfaghari 3
Affiliation  

Many bacteria including Escherichia coli can enter into the viable but non‐culturable (VBNC) state under unfavorable condition. This study investigated the fate of E. coli O157:H7 under high salinity stress in salted silver carp. E. coli O157:H7 was inoculated in distilled water and fish meat under 0, 10, and 30% NaCl at room temperature. The culturability of bacteria was investigated using culture‐based colony counting method. Viability and expression of pathogenic genes of E. coli O157:H7 were evaluated using reverse transcription polymerase chain reaction (RT‐PCR) of 16S rRNA, stx1, stx2, eae, and hly genes. The bacteria kept their culturability in both water microcosms and fish meat without salinity stress, however, bacterial culturabillity was lost under salinity of 10 and 30% in water microcosms on day 4 and in fish meat under salinity of 10% and 30%, respectively, on day 9 and 5. RT‐PCR showed positive expression of 16S rRNA in both culturable and non‐culturable bacteria indicating the entering of E. coli O157:H7 into the VBNC state under salinity stress. Moreover, VBNC E. coli O157:H7 kept the expression of its pathogenesis genes. So, E. coli O157: H7 in salted silver carp should be considered as a threat to public health and food safety.

中文翻译:

盐silver鱼中大肠杆菌O157:H7的存活但不可培养的状态及其致病基因的表达

在不利条件下,包括大肠杆菌在内的许多细菌都可以进入存活但不可培养的状态。这项研究调查了盐腌silver鱼在高盐度胁迫下大肠杆菌O157:H7的命运。在室温下,将大肠杆菌O157:H7接种在0%,10%和30%NaCl的蒸馏水和鱼肉中。使用基于培养物的菌落计数方法研究了细菌的可培养性。使用16S rRNAstx 1stx 2eaeE.coli的逆转录聚合酶链反应(RT-PCR)评价了O157:H7大肠杆菌的生存力和致病基因的表达。hly基因。细菌在水的微观世界和鱼肉中都保持了可培养性,没有盐分胁迫,但是,在第4天的水微观世界中,在盐度分别为10%和30%时和在盐分分别为10%和30%的鱼肉中,细菌的培养能力消失了。在第9天和第5天,RT-PCR在可培养和不可培养细菌中均显示16S rRNA阳性表达,这表明在盐分胁迫下大肠杆菌O157:H7进入VBNC状态。此外,VBNC大肠杆菌O157:H7保留了其发病基因的表达。因此,应将盐腌O鱼中的O157:H7大肠杆菌视为对公共健康和食品安全的威胁。
更新日期:2020-10-08
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