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Pathog Dis. 2016 Mar;74(2). pii: ftv123. doi: 10.1093/femspd/ftv123. Epub 2015 Dec 23.

Multiple mechanisms responsible for strong Congo-red-binding variants of Escherichia coli O157:H7 strains.

Author information

1
Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, U. S. Department of Agriculture, Wyndmoor, PA 19038, USA chin-yi.chen@ars.usda.gov.
2
Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, U. S. Department of Agriculture, Wyndmoor, PA 19038, USA.

Abstract

High variability in the expression of csgD-dependent, biofilm-forming and adhesive properties is common among Shiga toxin-producing Escherichia coli. Although many strains of serotype O157:H7 form little biofilm, conversion to stronger biofilm phenotypes has been observed. In this study, we screened different strains of serotype O157:H7 for the emergence of strong Congo-red (CR) affinity/biofilm-forming properties and investigated the underlying genetic mechanisms. Two major mechanisms which conferred stronger biofilm phenotypes were identified: mutations (insertion, deletion, single nucleotide change) in rcsB region and stx-prophage excision from the mlrA site. Restoration of the native mlrA gene (due to prophage excision) resulted in strong biofilm properties to all variants. Whereas RcsB mutants showed weaker CR affinity and biofilm properties, it provided more possibilities for phenotypic presentations through heterogenic sequence mutations.

KEYWORDS:

Congo red; O157:H7; STEC; biofilm; mlrA; rcsB

PMID:
26702633
DOI:
10.1093/femspd/ftv123
[Indexed for MEDLINE]

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