Frequent emergence of sigB mutant alleles in Listeria monocytogenes is likely to be linked to a growth advantage at elevated temperatures

International audience; Background: The food-borne pathogen Listeria monocytogenes is a Gram-positive bacteria and highly resistant to a variety of stresses. Such resistance is determinate by the activation of the alternative sigma factor B (σB). Genes within sigB operon encode for the signal transduction that controls σB activity. Mutations within this operon generally result on reduced σB activation. Objectives: Characterize the impact of secondary mutations within L. monocytogenes sigB operon, and identify laboratory conditions that promote the selection of such mutations among wild type (WT) populations. Methods: Transposon mutants (Tms) that lost the ability to form rings in response t…