The Production of Alkaline Protease from a Recombinant Strain Expressed Apr

The alkaline protease gene, Apr, from Bacillus licheniformis 2709 was cloned into an expression vector pET 28b(+). The pET-28b(+) Apr was expressed in a high expression strain E. coli BL21. In order to develop and optimize mathematical model of protease activity, three variables were investigated, including peptone concentration (6 g/L to 10 g/L), incubation time (16 h to 32 h) and agitation frequency (150 r/min to 240 r/min), by response surface methodology (RSM). The protease produced by recombinant strain with optimal protease activity was predicted to be obtained at: the peptone concentration 8.08 g/L, the incubation time 24.25 h and the agitation frequency 180.14 r/min. Under the optimal condition, the protease activity achieved 1125.81 U/mL.