(FTB-1962) Effect of Medium Composition on Commercially Important Alkaline Protease Production by Bacillus licheniformis N-2

Protease production by alkalophilic B. licheniformis N-2 was investigated in 50 mL of the growth medium consisting of (in g/L): glucose 10.0, soybean meal 10.0, K2HPO4 3.0, MgSO4·7H2O 0.5, NaCl 0.5 and CaCl2·2H2O 0.5 at pH=10. Different carbon and nitrogen sources in the form of fine powder of organic, inorganic and defatted meals were studied to select the suitable substrate for alkaline protease production. The highest level of alka-line protease (677.64 U/mL) was obtained in the medium containing glucose followed by soluble starch and wheat bran. Among various nitrogen sources, defatted soybean meal was found to be the best inducer of alkaline protease, while inorganic nitrogen sources in the form of ammonium salts repressed the enzyme activity up to 96 %. Thermostability studies showed that the enzyme in the presence of 10 mM Ca2+ ions retained its residual activity up to 80 % even after incubation at 40 °C for 12 h. The enzyme was found stable over a broad range of pH (8–11) and lost 52 % of its residual activity at pH=12. After th