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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #317195

Title: Comparative transcriptional profiling reveals differential expression of pathways directly and indirectly influencing biofilm formation in Escherichia coli O157:H7

Author
item Sharma, Vijay
item Alt, David
item Bayles, Darrell
item Looft, Torey
item Brunelle, Brian

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/16/2015
Publication Date: 8/20/2015
Citation: Sharma, V.K., Alt, D.P., Bayles, D.O., Looft, T.P., Brunelle, B.W. 2015. Comparative transcriptional profiling reveals differential expression of pathways directly and indirectly influencing biofilm formation in Escherichia coli O157:H7 [abstract]. Verocytotoxin Producing Escherichia Coli. p. 119.

Interpretive Summary:

Technical Abstract: Introduction: Escherichia coli O157:H7 (O157) is a frequent cause of foodborne disease outbreaks. O157 encodes virulence factors for colonizing and survival in reservoir animals and the environment. For example, genetic factors promoting biofilm formation are linked to survival of O157 in and outside the animal host. O157 strain 86-24, which neither binds Congo red (CR) nor produces biofilms, can generate CR-binding and biofilm-producing isolates at variable frequencies. Electron microscopy revealed the presence of higher amounts of curli (required for CR binding and biofilm formation) in a CR-binding isolate. In order to determine what other pathways besides curli biosynthesis were impacted, the RNA-Seq profile of a CR-binding isolate was compared to a CR-negative parental strain. Methods: The rRNA-depleted RNA of CR-binding and CR-negative parental isolates were used for preparing strand-specific RNA-seq libraries for sequencing with the Illumina HiSeq 2500. The reads were mapped to a reference genome (O157 EDL933) and analyzed for differential gene expression. Results and Discussion: Of 393 differentially regulated genes, 273 genes were down- and 120 genes were up-regulated in the CR-binding isolate. Among the up-regulated (greater than or equal to 2.0 fold; p less than 0.05) genes were those encoding curli biosynthesis and motility, corroborating phenotypic data reflecting increased CR binding, biofilm formation, and motility by the CR-binding isolate. Some of the down-regulated (greater than or equal to 2.0 fold; p less than 0.05) genes encoded for acid resistance, colanic acid biosynthesis, amino acid transport and biosynthesis, putrescine transport, and phage shock proteins. Transcriptional regulators, such as ctr capsule biosynthesis regulator RcsA, periplasmic stress response protein CpxP, and heat shock protein HtpX were significantly down-regulated. Implications: Since differential expression of pathways listed above is linked to biofilm formation and direct or indirect regulation by RcsA, CpxP, and HtpX, a genetic mechanism causing cumulative or hierarchical down-regulation of these regulators could enhance CR-binding and biofilm-producing ability of O157.