Under normal conditions (such as in rich media), the protein kinase SiaB dominates and maintains most SiaC phosphorylated, which failed to bind to SiaD or induce the DGC activity of SiaD; therefore, c-di-GMP is insufficient to activate the biofilm and aggregate formation. Once under stress conditions (such as SDS stimulation), SiaA phosphatase is activated and most SiaC stays unphosphorylated; in this situation, the unphosphorylated SiaC promotes the DGC activity of SiaD and produces sufficient c-di-GMP, which leads to aggregate and biofilm formation. 