Bioprospecting of soybean for production of nattokinase

Abstract

Nattokinase (NK), a fibrinolytic enzyme, is produced by solid-state fermentation (SSF) of soybean (DS 9814) by Bacillus subtilis MTCC 2616 using a rotating bioreactor. Glucose, casein, K2HPO4, FeSO4 and hypoxanthine were found to be the most influential components for maximum NK production as obtained from Plackett-Burman design. The optimum values of nutrients per (100 g of solid substrate) determined by response surface methodology were glucose 2 g, casein 1 g, K2HPO4 0.30 g, FeSO4 0.01 g and hypoxanthine 1 mg. These values predicted menaquinone-7 of 0.007 μg g−1 and NK with 310±2 FU g−1 (dry weight) of fermented soybean by B. subtilis MTCC 2616 under SSF. Crude NK was found to be stable in the range of 30–60°C, retaining 85% of its initial fibrinolytic activity. Thermodynamic parameters ΔH* (deactivation enthalpy) and δS* (deactivation entropy) for crude NK were found to be −335 kJ mol−1 and 5.34 kJ (mol K)−1 respectively.