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Abstract
RpoS, an alternative sigma subunit of RNA polymerase, is known to be involved in eliciting a general stress response in Escherichia coli. The aim of this study was to determine whether RpoS was necessary for the improved o heat tolerance at 50 C previously observed in Escherichia coli pre-treated with sub-inhibitory kanamycin. Spread plating was done to assess cell viability before and after heat treatment in wildtype Escherichia coli and an isogenic Δ rpo S mutant. Western blotting was used to evaluate RpoS expression levels in both strains and to confirm the rpo S knockout. Our viability assay results showed reduced cell viability in both strains after kanamycin pretreatment, and the Δ rpo S strain showed similar and higher percent viability compared to the wildtype in control and kanamycin treatment groups, respectively. Induction of RpoS was seen in the wildtype with pre-treatment of sub-inhibitory kanamycin and after heat treatment. Our findings indicate that RpoS was not necessary for inducing heat tolerance.