Header

UZH-Logo

Maintenance Infos

In vitro characterization of Shiga toxin-producing and generic Escherichia coli in respect of cheese-production relevant stresses


Peng, S; Stephan, R; Hummerjohann, J; Blanco, J; Zweifel, C (2012). In vitro characterization of Shiga toxin-producing and generic Escherichia coli in respect of cheese-production relevant stresses. Journal of Food Safety and Food Quality, 63(5):136-141.

Abstract

Forty-one Escherichia (E.) coli strains from raw milk cheese, including 26 Shiga toxin-producing strains (STEC), and six STEC strains from cattle feces were characterized in respect of cheese production-relevant stress (thermal inactivation, glucose-repressed oxidative acid resistance system, acidic and osmotic stress). Of all 47 E. coli isolates, seven generic E. coli strains showed an increased heat tolerance (55 °C, 15 min) and 20 strains (STEC and generic E. coli) exhibited a survival rate of ≥10 % (pH 2.5, 2 h) with induced oxidative acid resistance system. Besides, growth was observed for all E. coli strains at pH or aw values commonly found in (semi-hard) cheese (pH=5.2, aw=0.970), whereas counts tended to decrease at a pH value of 4.5 or an aW value of 0.942. Overall, no clear and universal differences between STEC and generic E. coli strains were found. The large strain variations observed in respect of the applied stresses within this strain collection do not indicate a shared feature amongst our E. coli strains that may be beneficial for their survival in raw milk cheese. It remains to be elucidated if there are key factors enabling the survival of E. coli and in particular STEC during production of raw milk cheese or if differences in the production process are more important.

Abstract

Forty-one Escherichia (E.) coli strains from raw milk cheese, including 26 Shiga toxin-producing strains (STEC), and six STEC strains from cattle feces were characterized in respect of cheese production-relevant stress (thermal inactivation, glucose-repressed oxidative acid resistance system, acidic and osmotic stress). Of all 47 E. coli isolates, seven generic E. coli strains showed an increased heat tolerance (55 °C, 15 min) and 20 strains (STEC and generic E. coli) exhibited a survival rate of ≥10 % (pH 2.5, 2 h) with induced oxidative acid resistance system. Besides, growth was observed for all E. coli strains at pH or aw values commonly found in (semi-hard) cheese (pH=5.2, aw=0.970), whereas counts tended to decrease at a pH value of 4.5 or an aW value of 0.942. Overall, no clear and universal differences between STEC and generic E. coli strains were found. The large strain variations observed in respect of the applied stresses within this strain collection do not indicate a shared feature amongst our E. coli strains that may be beneficial for their survival in raw milk cheese. It remains to be elucidated if there are key factors enabling the survival of E. coli and in particular STEC during production of raw milk cheese or if differences in the production process are more important.

Statistics

Citations

7 citations in Web of Science®
8 citations in Scopus®
Google Scholar™

Altmetrics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:05 Vetsuisse Faculty > Institute of Food Safety and Hygiene
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:2012
Deposited On:11 Mar 2013 09:03
Last Modified:05 Apr 2016 16:37
Publisher DOI:https://doi.org/10.2376/0003-925X-63-136

Download

Full text not available from this repository.
View at publisher

TrendTerms

TrendTerms displays relevant terms of the abstract of this publication and related documents on a map. The terms and their relations were extracted from ZORA using word statistics. Their timelines are taken from ZORA as well. The bubble size of a term is proportional to the number of documents where the term occurs. Red, orange, yellow and green colors are used for terms that occur in the current document; red indicates high interlinkedness of a term with other terms, orange, yellow and green decreasing interlinkedness. Blue is used for terms that have a relation with the terms in this document, but occur in other documents.
You can navigate and zoom the map. Mouse-hovering a term displays its timeline, clicking it yields the associated documents.

Author Collaborations