Alternative transcription factor σB is involved in regulation of biofilm expression in a Staphylococcus aureus mucosal isolate

Osmotic stress was found to induce biofilm formation in a Staphylococcus aureus mucosal isolate. Inactivation of a global regulator of the bacterial stress response, the alternative transcription factor sigma (B), resulted in a biofilm-negative phenotype and loss of salt-induced biofilm production. Complementation of the mutant strain with an expression plasmid encoding sigma (B) completely restored the wild-type phenotype. The combined data suggest a critical role of sigma (B) in S. aureus biofilm regulation under environmental stress conditions.