Relative gene expression in acid-adapted Escherichia coli O157:H7 during lactoperoxidase and lactic acid challenge in Tryptone Soy Broth

Parry-Hanson, Angela Araba Bondzewaa; Jooste, Piet J.; Buys, E.M. (Elna Maria)

dc.contributor.author	Parry-Hanson, Angela Araba Bondzewaa
dc.contributor.author	Jooste, Piet J.
dc.contributor.author	Buys, E.M. (Elna Maria)
dc.date.accessioned	2010-02-01T07:31:24Z
dc.date.available	2010-02-01T07:31:24Z
dc.date.issued	2010
dc.description.abstract	Cross-protection of acid-adapted Escherichia coli O157:H7 against inimical stresses is mediated by the glucose-repressed sigma factor RpoS. However, many food systems in which E. coli O157:H7 occurs are complex and contain glucose. This study was aimed at investigating the contribution of acid and lactoperoxidase(LP)-inducible genes to cross- protection of E. coli O157:H7 against LP system and lactic acid(LA)in Tryptone Soy Broth(TSB). Acid-adapted and non-adapted E. coli O157:H7 were challenged to activated LP and LA at pH4.0 and 5.0 in TSBf or 6 h at 25 1C followed by expression of acid and LP- inducible genes. Acid-adapted E. coli showed cross-protection against activated LP and LA. All the acid-inducible genes tested were repressed at pH4.0 with or without activated LP system. At pH7.4, gadA, ompC and ompF were induced in acid-adapted cells. Induction of corA occurred in non-adapted cells but was repressed in acid-adapted cells. Although acid-inducible genes were repressed at pH4.0, high resistance of acid-adapted cells indicates that expression of acid-inducible genes occurred during acid adaptation and not the actual challenge. Repression of rpoS indicates that RpoS-independent systems contribute to cross-protection in acid-adapted E. coli O157:H7.	en
dc.identifier.citation	Parry-Hanson AA, et al. Relative gene expression in acid-adapted Escherichia coli O157:H7 during lactoperoxidase and lactic acid challenge in Tryptone Soy Broth. Microbiol Res 2006;(2009),doi:10.1016/j.micres.2009.11.003	en
dc.identifier.issn	0944-5013
dc.identifier.other	10.1016/j.micres.2009.11.003
dc.identifier.uri	http://hdl.handle.net/2263/12808
dc.language.iso	en	en
dc.publisher	Elsevier	en
dc.rights	Elsevier	en
dc.subject	Cross-protection	en
dc.subject	Lactoperoxidase	en
dc.subject	Acid-adaptation	en
dc.subject	Real-time PCR	en
dc.subject.lcsh	Escherichia coli O157:H7	en
dc.subject.lcsh	Gene expression	en
dc.subject.lcsh	Lactic acid	en
dc.title	Relative gene expression in acid-adapted Escherichia coli O157:H7 during lactoperoxidase and lactic acid challenge in Tryptone Soy Broth	en
dc.type	Postprint Article	en