Alternative Sigma Factor σE Has an Important Role in Stress Tolerance of Yersinia pseudotuberculosis IP32953

Yersinia pseudotuberculosis is an important pathogen that probably survives well in the modern food chain. However, little is known about the mechanisms that allow the growth of this pathogen in foods under stress conditions. The expression of rpoE encoding sigma(E) was defined by quantitative real-time reverse transcription-PCR. Expression of rpoE was induced at 3 degrees C, 37 degrees C, and 42 degrees C, under exposure to 3% NaCl, 3% ethanol, or high and low pH, in relation to its expression at the optimum growth temperature of 28 degrees C of Y. pseudotuberculosis. Mutation of rpoE either impaired or abolished growth under stresses caused by low or high temperature, low pH, and ethanol. In addition, the growth temperature range of the mutant was significantly diminished compared to that of the wild-type strain IP32953. The results were confirmed with complementation of the mutant. Thus, sigma(E) plays a significant role in the stress tolerance of Y. pseudotuberculosis IP32953 and probably contributes to the survival of this pathogen in the food chain.