Selection and Characterization of Cellulose-Deficient Derivates of Shiga Toxin–Producing Escherichia coli

Abstract

Shiga toxin–producing Escherichia coli (STEC) is known to have several defense mechanisms, one of which is the production of extracellular substances including cellulose. The goal of this study was to prepare pairs of STEC cultures for use in future studies designed to address the role of cellulose in protecting the cells of STEC for survival under adverse environmental conditions. Cells of STEC deficient in cellulose production were separated from cellulose-proficient wild-type cells. The identities of the two types of cells were confirmed using serotyping and pulsed-field gel electrophoresis (PFGE). Selected growth characteristics of the two types of cells were determined using three phenotype microarray plates, PM9, PM10, and PM11. The cellulose-deficient and cellulose-proficient cells in each STEC pair shared the same serotype and PFGE profile. The deficiency in cellulose production did not significantly (P > 0.05) affect the growth characteristics of STEC cells under 191 of the 210 tested growth conditions. Significant differences in growth between the two types of cells were observed only in the presence of two antibiotics, a short chain fatty acid, and high concentrations of osmolytes, as well as under extreme acidic and alkaline pH. These results suggest that deficiency in cellulose production did not alter the serological property, PFGE profile, and growth characteristics of selected STEC strains under optimal growth conditions. The STEC strains and their cellulose-deficient derivates could be useful for studying the role of cellulose in protecting the cells of STEC for survival under adverse environmental conditions.