Application of Box-Behnken Design for the Optimization of Culture Conditions for Novel Fibrinolytic Enzyme Production by Bacillus altitudinis S-CSR 0020

A bacterium which produced novel extracellular fibrinolytic enzyme for digesting bovine blood clots was isolated from soil, and identified by 16s rRNA sequencing as Bacillus altitudinis, given strain name was S-CSR 0020 (accession number KT369312). Fibrin proved the best nitrogen source with an enzyme activity of 750 U/mL, followed by casein after incubation at 37 °C for 4 days. The cultural conditions were optimised using Response Surface Methodology (RSM) and Box-Behnken Design (BBD). Based on 3D surface plot and contour plots, the optimized temperature, pH and substrate concentrations were 47 °C, 10.5 and 4 g/L respectively, resulted in increase in enzyme activity of 306.88 U/mL and specific activity of 780 U/mg which was 2-fold; compared to initial level of 400 U/mg after 2 days of incubation. The crude enzyme has got potent activity and digested human blood clot completely within 1 hr.