Enhanced production of fibrinolytic protease from Bacillus cereus NS-2 using cotton seed cake as nitrogen source

• Bacillus cereus NS-2 showed proficient fibrinolytic protease producing ability.
• Wheat/rice bran served as admirable substrates for fibrinolytic protease production.
• Cotton cake as nitrogen source enhanced protease production substantially (71%).
• Fe2+, Ca2+, Mn2+, Zn2+, Cu2+, Mg2+ enhanced activity of partially purified (2.35-fold) protease.
• Protease showed reasonable stability towards Triton X-100, Tween 20 and EDTA.

Cardiovascular complications due to thrombosis have become one of the major causes of mortality. High cost and fatally undesired side effects associated with the available thrombolytic agents motivated the researchers to investigate potentially better agents for therapeutic applications. In the current study, production of an efficacious fibrinolytic protease from a bacterial isolate Bacillus cereus NS-2 was optimized by employing low-cost agricultural residues as substrates (wheat bran and cotton cake at 1%, w/v, each). Wheat bran supported fibrinolytic protease production (148 U/ml) that was comparable with control (145.5 U/ml on glucose). Cotton cake as nitrogen source enhanced fibrinolytic protease production substantially (71%) as compared to control (315 U/ml vs 184 U/ml). Fibrinolytic protease was partially purified (2.35-fold) by ammonium sulfate precipitation and diethylaminoethyl-sepharose chromatography with the yield of 58.27%. Maximum activity of partially purified fibrinolytic protease was observed at 40 °C and at pH 9. Fibrinolytic protease activity was increased immensely by Fe2+ (76.6%) and moderately by Ca2+, Mn2+, Zn2+, Cu2+ and Mg2+ (29–44%), however, Pb2+ and Hg2+ strongly inhibited the protease. B. cereus NS-2 protease showed reasonable stability in presence of Triton X-100 and Tween 20 (relative activity 87 and 80%, respectively) but poor stability in presence SDS (relative activity 29%). Retention of considerable activity (46%) in presence of EDTA reflects that requirement of divalent ions is not absolute for catalysis by B. cereus NS-2 fibrinolytic protease.