FIG. 4.

Growth and expression of the lacZ reporter of strains of B. subtilis. Strains BFS47 (ytrF-pMUTIN2mcs) (A), BFS45 (Pytr::pMUTIN2mcs) (B), and BFS53 (ΔytrA::pMUTIN2mcs) (C) were grown in MM (open square, β-galactosidase activity; open circle, cell density) and in MM with 1 mM IPTG (closed square, β-galactosidase activity). Strain 168 (wild type) was also grown in MM (open triangle, β-galactosidase activity; closed circle, cell density) and in MM with 1 mM IPTG (closed triangle, β-galactosidase activity). (D) Strains BFS47 (squares, β-galactosidase activity; diamonds, cell density) and 168 (closed triangle, β-galactosidase activity; closed circle, cell density) were grown in DSM supplemented with (open symbols) and without (closed symbols) 5 mM acetoin; exogenous acetoin was added to the culture 3 h after the inoculation. The experiments were repeated at least three times for each strain and medium with similar results; representative results are shown. β-Galactosidase activity (nanomoles of 2-nitrophenyl-β-d-galactopyranoside hydrolyzed per minute per milligram of protein) was determined as described previously (28).