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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Characterization and Interventions for Foodborne Pathogens » Research » Publications at this Location » Publication #327313

Research Project: Shiga Toxin-Producing Escherichia coli in Biofilms and within Microbial Communities in Food

Location: Characterization and Interventions for Foodborne Pathogens

Title: Stx1 prophage excision in Escherichia coli strain PA20 confers strong curli and biofilm formation by restoring native mlrA

item Uhlich, Gaylen
item Chen, Chinyi
item Cottrell, Bryan
item Yan, Xianghe
item HOFMANN, CHRISTOPHER - Vanderbilt University Medical Center
item Nguyen, Ly Huong

Submitted to: FEMS Microbiology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2016
Publication Date: 5/5/2016
Publication URL:
Citation: Uhlich, G.A., Chen, C., Cottrell, B.J., Yan, X., Hofmann, C.S., Nguyen, L.T. 2016. Stx1 prophage excision in Escherichia coli strain PA20 confers strong curli and biofilm formation by restoring native mlrA. FEMS Microbiology Letters. doi: 10.1093/femsle/fnw123.

Interpretive Summary: Shiga toxin-producing Escherichia coli (STEC) are food-borne pathogenic bacteria that include serotype O157:H7, which have been associated with large outbreaks of bloody diarrhea that are often fatal for children, the elderly, and immunocompromised adults. We have previously shown that a bacterial virus often inserts into a regulatory gene that controls biofilm formation (bacteria forming large aggregates on surfaces) and resistance to food-related stress in E. coli serotype O157:H7, severely limiting its ability to survive in the environment. However, small numbers of these virus-infected cells can spontaneously lose the virus. In this study, we show that when the virus is cured from the chromosome of STEC O157:H7, the regulatory gene is reformed, restoring stress resistance. This provides a strong mechanism for increasing the survival and persistence of this important pathogen. This mechanism offers an important new target for developing drugs or virus-based therapies for controlling STEC outbreaks.

Technical Abstract: Prophage insertions in Escherichia coli O157:H7 mlrA contribute to the low expression of curli fimbriae and biofilm observed in many clinical isolates. Varying levels of CsgD-dependent curli/biofilm expression are restored to strains bearing prophage insertions in mlrA by mutation of regulatory genes affecting csgD. Our previous study identified strong biofilm- and curli-producing variants in O157:H7 cultures that had lost the mlrA-imbedded prophage characteristic of the parent population, suggesting prophage excision as a mechanism for restoring biofilm properties. In this study we compared genomic, transcriptomic, and phenotypic properties of parent strain PA20 (stx1, stx2) and its prophage-cured variant, 20R2R (stx2), and confirmed the mechanism underlying the differences in biofilm formation.