FIG 6 .

Acetate salts stimulate early biofilm formation by enhancing expression of the matrix genes. (A) Pellicle formation by wild-type B. subtilis cells (strain 3610) in LBGM medium or LBGM medium plus 0.2% NaAc or LBGM medium plus 0.2% NaCl, after 24 h of incubation at 30°C. Early pellicle formation was seen for cells growing in LBGM medium plus 0.2% NaAc. (B and C) Assays of β-galactosidase activities by B. subtilis cells harboring either the P_tapA-lacZ (YC121) (B) or the P_epsA-lacZ (YC110) (C) transcriptional reporter. Cells were grown in LB shaking culture in the presence or absence of 0.2% NaAc and were harvested when the OD₆₀₀ of the cultures reached 2.0.