Transcriptome analysis of sorbic acid stressed Bacillus subtilis reveals a nutrient limitation response and indicates plasma membrane remodeling

Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands

^* To whom correspondence should be addressed. Email: aterbeek{at}science.uva.nl.

	Abstract

The weak organic acid sorbic acid is a commonly used food preservative, as it inhibits the growth of bacteria, yeasts and molds. We have used genome-wide transcriptional profiling of Bacillus subtilis cells during mild sorbic acid stress to reveal the growth inhibitory activity of this preservative and to identify potential resistance mechanisms. Our analysis demonstrated that sorbic acid stressed cells induce responses normally seen upon nutrient limitation. This is indicated by the strong de-repression of the CcpA, CodY and Fur regulon, the induction of TCA cycle genes, SigL and SigH mediated genes, and the stringent response. Intriguingly, these conditions did not lead to the activation of sporulation, competence, or the general stress response (GSR). The fatty acid biosynthesis (fab) genes and BkdR regulated genes are upregulated, which may indicate plasma membrane remodeling. This was further supported by the reduced sensitivity towards the fab inhibitor cerulenin upon sorbic acid stress. We are the first to present a comprehensive analysis of the transcriptional response of B. subtilis to sorbic acid stress.