Fig. 4

Growth and alkaline protease production of four B. pumilus strains. (A) The growth curves of four bacterial strains in LB (+ 0.2% gelatin) medium (37 °C, 200 rpm, aerobically). (B) The growth curves of four bacterial strains in fermentation medium (37 °C, 200 rpm, aerobically). (C) The extracellular alkaline protease activity of four strains in LB (+ 0.2% gelatin) medium (37 °C, 200 rpm, aerobically). (D) The extracellular alkaline protease activity of four bacterial strains in the fermentation medium (37 °C, 200 rpm, aerobically). The data were applied to student t-test with p < 0.05 (*), 0.01 (**) and 0.001 (***) compared with SCU11 at the same time points