The change in heat inactivation of Escherichia coli O157:H7 after entering into the viable but non-culturable state in salted fish, Hypophthalmichthys molitrix

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 O157:H7 after entering into the VBNC state in salted silver carp, Hypophthalmichthys molitri...

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Main Authors:	Mohammad Khezri, Masoud Rezaei, Ashraf Mohabbati Mobarez, Mehdi Zolfaghari
Format:	article
Language:	EN
Published:	University of Guilan 2021
Subjects:	escherichia coli o157:h7 vbnc state thermal resistance Environmental sciences GE1-350 Science Q
Online Access:	https://doaj.org/article/ffe56dbc376349d487a4531408a3ebd9
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spelling	oai:doaj.org-article:ffe56dbc376349d487a4531408a3ebd92021-12-02T20:25:58ZThe change in heat inactivation of Escherichia coli O157:H7 after entering into the viable but non-culturable state in salted fish, Hypophthalmichthys molitrix1735-30331735-386610.22124/cjes.2021.5136https://doaj.org/article/ffe56dbc376349d487a4531408a3ebd92021-10-01T00:00:00Zhttps://cjes.guilan.ac.ir/article_5136_34350fb37be0093b2609c2b09c64f231.pdfhttps://doaj.org/toc/1735-3033https://doaj.org/toc/1735-3866Many 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 O157:H7 after entering into the VBNC state in salted silver carp, Hypophthalmichthys molitrix, was investigated. E. coli O157:H7 was inoculated on the fish control group (TF) and on those fish with 30% NaCl (TF + 30% 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 16S 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 O157:H7. Also, cultivable and VBNC E. coli O157:H7 were individually heat-treated at 55, 62 and 70 °C for 5 min. The samples were cooled and after 24 h, the thermal resistance of bacteria was determined through viability detection using RT-PCR of 16S rRNA gene. The culturability of bacteria was kept in fish treatment but they were non-cultivable in fish under 30% NaCl after 5 days. The positive expression of 16S rRNA in all studied treatments indicated the entering of E. coli O157:H7 into the VBNC state in fish treatment under 30% NaCl. Moreover, the RT-PCR of 16S rRNA gene showed that only VBNC forms of E. coli O157:H7 showed viability at 62 °C for 5 min which indicated the increased resistant of VBNC bacteria to the thermal inactivation. The ability of E. coli O157:H7 to enter into VBNC state in salted fish and also the increase of its thermal resistance suggest that VBNC E. coli O157: H7 can be considered as critical threat to public health and food safety.Mohammad KhezriMasoud RezaeiAshraf Mohabbati MobarezMehdi ZolfaghariUniversity of Guilanarticleescherichia coli o157:h7vbnc statethermal resistanceEnvironmental sciencesGE1-350ScienceQENCaspian Journal of Environmental Sciences , Vol 19, Iss 4, Pp 629-637 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	escherichia coli o157:h7 vbnc state thermal resistance Environmental sciences GE1-350 Science Q
spellingShingle	escherichia coli o157:h7 vbnc state thermal resistance Environmental sciences GE1-350 Science Q Mohammad Khezri Masoud Rezaei Ashraf Mohabbati Mobarez Mehdi Zolfaghari The change in heat inactivation of Escherichia coli O157:H7 after entering into the viable but non-culturable state in salted fish, Hypophthalmichthys molitrix
description	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 O157:H7 after entering into the VBNC state in salted silver carp, Hypophthalmichthys molitrix, was investigated. E. coli O157:H7 was inoculated on the fish control group (TF) and on those fish with 30% NaCl (TF + 30% 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 16S 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 O157:H7. Also, cultivable and VBNC E. coli O157:H7 were individually heat-treated at 55, 62 and 70 °C for 5 min. The samples were cooled and after 24 h, the thermal resistance of bacteria was determined through viability detection using RT-PCR of 16S rRNA gene. The culturability of bacteria was kept in fish treatment but they were non-cultivable in fish under 30% NaCl after 5 days. The positive expression of 16S rRNA in all studied treatments indicated the entering of E. coli O157:H7 into the VBNC state in fish treatment under 30% NaCl. Moreover, the RT-PCR of 16S rRNA gene showed that only VBNC forms of E. coli O157:H7 showed viability at 62 °C for 5 min which indicated the increased resistant of VBNC bacteria to the thermal inactivation. The ability of E. coli O157:H7 to enter into VBNC state in salted fish and also the increase of its thermal resistance suggest that VBNC E. coli O157: H7 can be considered as critical threat to public health and food safety.
format	article
author	Mohammad Khezri Masoud Rezaei Ashraf Mohabbati Mobarez Mehdi Zolfaghari
author_facet	Mohammad Khezri Masoud Rezaei Ashraf Mohabbati Mobarez Mehdi Zolfaghari
author_sort	Mohammad Khezri
title	The change in heat inactivation of Escherichia coli O157:H7 after entering into the viable but non-culturable state in salted fish, Hypophthalmichthys molitrix
title_short	The change in heat inactivation of Escherichia coli O157:H7 after entering into the viable but non-culturable state in salted fish, Hypophthalmichthys molitrix
title_full	The change in heat inactivation of Escherichia coli O157:H7 after entering into the viable but non-culturable state in salted fish, Hypophthalmichthys molitrix
title_fullStr	The change in heat inactivation of Escherichia coli O157:H7 after entering into the viable but non-culturable state in salted fish, Hypophthalmichthys molitrix
title_full_unstemmed	The change in heat inactivation of Escherichia coli O157:H7 after entering into the viable but non-culturable state in salted fish, Hypophthalmichthys molitrix
title_sort	change in heat inactivation of escherichia coli o157:h7 after entering into the viable but non-culturable state in salted fish, hypophthalmichthys molitrix
publisher	University of Guilan
publishDate	2021
url	https://doaj.org/article/ffe56dbc376349d487a4531408a3ebd9
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The change in heat inactivation of Escherichia coli O157:H7 after entering into the viable but non-culturable state in salted fish, Hypophthalmichthys molitrix

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