The TCA was removed, and the cells were washed five times with DI water, then staining with 0.4% (w/v) SRBdissolved in 1% (v/v) acetic acid for 30 min at room temperature. Unbound dye was removed using five washes of1% (v/v) acetic acid, after which the cells were solubilized with 10 mM unbuffered Tris base (pH 10.0).