Enhanced Production and Physicochemical Properties of a Commercially Viable Alkaline Protease from Bacillus amyloliquefaciens PFB-01

Bacillus amyloliquefaciens PFB-01 produced extracellular alkaline protease (385.25 U/ml) under shake flask conditions. Effects of process parameters such as cultivation period, pH, temperature, carbon and nitrogen sources on protease production were investigated for optimization. Production of protease was optimized with 5.0% inoculum size in culture medium (pH 8.0) incubated for 48 h at 37°C and 200 rpm. A combination of gelatin (0.75%) as nitrogen source and glucose (0.5%) as carbon source gave maximum yield of protease (525.82U/mL) which was 138% increase over enzyme yield in basal media. Soybean meal (0.75%) and glucose (0.5%) supported protease yield of 510.5 U/ml and 134% increase over basal media. The protease had optimum pH and temperature of 9.0 and 60 °C. Remarkably, it showed 60% residual activity after 60 min of incubation at 60 ºC in the absence of CaCl2. Protease activity was enhanced in the presence of most organic solvents studied and most stable in the presence of 25% DMSO with residual activity of 93.7%. The enzyme was compatible with the commercial detergents tested. Production of this protease in optimized media with inexpensive and readily available soybean meal as alternative nitrogen source indicates that its production can be cost effective for industrial applications. The physicochemical properties exhibited by the protease from B. amyloliquefaciens PFB-01 make this enzyme commercially viable for exploitation in detergent industry and ester synthesis.