The Role of wza in Extracellular Capsular Polysaccharide Levels During Exposure to Sublethal Doses of Streptomycin

Abstract

It has been previously shown that treatment of Escherichia coli with streptomycin triggers an increase in capsular polysaccharide (CPS) production. In this study, we investigated whether an increased export of CPS to the cell surface and therefore a thicker CPS is correlated with streptomycin resistance. This was done by using a strain lacking wza which codes for a protein involved in the transport of CPS polymers to the cell surface. The results of the anthrone assay revealed that extracellular CPS levels following stimulation with sublethal concentrations of streptomycin was lower for the Δ wza strain compared to the wild-type (WT) strain indicating that exposure to the antibiotic does indeed induce CPS production and export and also confirmed the role of wza in CPS transport. Furthermore, it was seen that WT treated cells were more resistant to the lethal antibiotic concentrations indicating a role for the thicker CPS in antibiotic resistance. However, the Δ wza strain did not display a lower level of resistance to antibiotics.