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Front. Microbiol. | doi: 10.3389/fmicb.2018.02829

Pch genes control biofilm and cell adhesion in a clinical serotype O157:H7 isolate

 Elisa Andreozzi1,  Nereus W. Gunther IV1*, Erin R. Reichenberger1, Luca Rotundo1, Bryan J. Cottrell1, Alberto Nunez1 and  Gaylen A. Uhlich1*
  • 1Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, United States

In a previous study, induction of the Escherichia coli serotype O157:H7 SOS response decreased csgD expression in the clinical isolate PA20 at 30°C but strongly induced genes in the horizontally-transferred-DNA regions (HTR), including many known virulence regulators. To determine the role of HTR regulators in the control of csgD and curli, specific regulators were plasmid-expressed in wild-type and mutant strains of PA20 and its strong biofilm-forming derivative, 20R2R. The O157:H7 group 3 perC homologue, pchE, strongly repressed csgD and CsgD-dependent phenotypes such as biofilm formation and Congo red dye affinity in a ler-independent manner at 30°C. At 37°C under non-SOS inducing conditions, curli, rather than espA, contributed to host cell adhesion and pchE was capable of minimizing the curli-dependent cell adherence, providing a host-adapting adhesion control mechanism. Expression of pchE was also repressed during SOS response induction at 37°C, providing a mechanism by which curli expression might complement the group1 pch initiated espA-dependent intimate adhesion.

Keywords: E. coli O157:H7, biofilm control, Cell Adhesion, curli, horizontally transferred DNA regions, pch regulatory genes, Locus of Enterocyte Effacement, pchE gene

Received: 03 Aug 2018; Accepted: 05 Nov 2018.

Edited by:

Alain P. Gobert, Vanderbilt University Medical Center, United States

Reviewed by:

Maria T. Brandl, Agricultural Research Service, United States Department of Agriculture, United States
Jay Mellies, Reed College, United States  

Copyright: © 2018 Andreozzi, Gunther IV, Reichenberger, Rotundo, Cottrell, Nunez and Uhlich. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Dr. Nereus W. Gunther IV, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Molecular Characterization of Foodborne Pathogens Research Unit, Wyndmoor, United States, jack.gunther@ars.usda.gov
Dr. Gaylen A. Uhlich, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Molecular Characterization of Foodborne Pathogens Research Unit, Wyndmoor, United States, gaylen.uhlich@ars.usda.gov