σ B Inhibits Poly- N -Acetylglucosamine Exopolysaccharide Synthesis and Biofilm Formation in Staphylococcus aureus

Abstract

Due to its multifaceted lifestyle, Staphylococcus aureus needs a complex regulatory network to connect environmental signals with cellular physiology. One particular transcription factor, named σ B (SigB), is involved in the general stress response and the expression of virulence factors. For many years, great confusion has existed about the role of σ B in the regulation of the biofilm lifestyle in S. aureus . Our study demonstrated that σ B is not necessary for exopolysaccharide-dependent biofilms and, even more, that S. aureus produces stronger biofilms in the absence of σ B . The increased accumulation of exopolysaccharide correlates with higher stability of the proteins responsible for its synthesis. The present findings reveal an additional regulatory layer to control biofilm exopolysaccharide synthesis under stress conditions.