Sugar-responsive gene expression and the agr system are required for colony spreading in Staphylococcus aureus

Staphylococcus aureus spreads on soft agar surfaces, which is called “colony spreading”. Here, we report that the colony spreading in S. aureus was promoted by the addition of glucose to soft agar plates. Disruption of ccpA and hprK, which are involved in catabolite repression, decreased the colony spreading ability promoted by glucose. Deletion of the agr locus, a virulence regulatory element whose expression is activated by glucose in a ccpA-dependent manner, abolished the colony spreading promoted by glucose. Disruption of clpP and arlRS, which contributes to agr expression, also decreased glucose-promoted colony spreading. These findings suggest that S. aureus colony spreading requires the expression of agr, which is positively regulated by environmental carbon sources, and that virulence gene expression and colony spreading induced by agr are simultaneously activated in the S. aureus infectious process.