FIG. 2.

Identification of prophage 1-specific genes involved in LipA production. (A) LipA activities in the growth media of B. subtilis 168, Δ6, Δ1, 168 skfD, and Δ1 albA containing pLip2031 for the overproduction of LipA. Cells were grown overnight in LB medium at 37°C and separated from the growth medium by centrifugation. Growth medium fractions were used for lipase activity determinations as described in Materials and Methods. Numbers are averages for four independent cultures. LipA activity was calculated as the increase in the absorbance at 405 nm · min⁻¹ per OD unit and is presented as a percentage of the lipase activity in the growth medium of the parental strain 168 (100%). Error bars indicate the standard deviations of the biological repeats. (B) LipA production and secretion. Cells from B. subtilis 168, Δ6, Δ1, 168 skfD, and Δ1 albA containing pLip2031 for the overproduction of LipA were grown overnight in LB medium at 37°C and separated from the growth medium by centrifugation. Proteins in the growth medium were concentrated by precipitation with TCA, and samples for SDS-PAGE and Western blotting were prepared. LipA was visualized by using LipA-specific antibodies.