Identification of Bacillus subtilis σW-dependent genes that provide intrinsic resistance to antimicrobial compounds produced by Bacilli

Abstract

Bacillus subtilis produces many antibiotics of varying structures and specificity. Here we identify a prominent role for σW, an extracytoplasmic function (ECF) sigma factor, in providing intrinsic resistance to antimicrobial compounds produced by other Bacilli. By using a panel of B. subtilis mutants disrupted for each of the 30 known σW- dependent operons we identified resistance genes for at least three different antimicrobial compounds. The ydbST and fosB genes contribute to resistance to antimicrobial compound(s) produced by B. amyloliquefaciens FZB42, the yqeZyqfAB operon provides resistance to the SPβ prophage-encoded bacteriocin sublancin, and the yknWXYZ operon and yfhL provide resistance to the antimicrobial peptide SdpC. YfhL encodes a paralogue of SdpI, a membrane protein that provides immunity to SdpC. In competition experiments, we identify σW as a key factor in allowing B. subtilis to resist antibiotic killing and encroachment by competing strains. Together with the previous observation that σW provides inducible resistance against the Streptomyces antibiotic fosfomycin, these studies support the notion that σW controls an antibiosis regulon important in the microbial ecology of soil bacteria. © 2006 Blackwell Publishing Ltd.