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Viable but non culturable state and expression of pathogenic genes of Escherichia coli O157 : H7 in salted silver carp
Author(s) -
Khezri Mohammad,
Rezaei Masoud,
Mohabbati Mobarez Ashraf,
Zolfaghari Mehdi
Publication year - 2020
Publication title -
journal of food safety
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 43
eISSN - 1745-4565
pISSN - 0149-6085
DOI - 10.1111/jfs.12843
Subject(s) - escherichia coli , microbiology and biotechnology , bacteria , salinity , 16s ribosomal rna , biology , pathogenic bacteria , carp , food science , microcosm , gene , fish <actinopterygii> , fishery , biochemistry , ecology , genetics
Abstract 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 , stx 1 , stx 2 , 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.