Protease production from soybean residue by solid state fermentation using Bacillus subtilis

Abstract

Soybean residue is the residue after the manufacture of soymilk. In this research, soybean residue was recycled back in order to prevent the environmental issues that rise due to the accumulation of the soybean wastes. Due to the high moisture content of soybean residue, it can be used as a substrate for the production of protease. Since protease enzyme are very expensive in the global market, an alternative method was apply in order to reduce the production cost. The project aims to study the growth profile of Bacillus subtilis and to optimize the protease production for higher yield. Protease enzyme was produced by Bacillus subtilis via solid state fermentation at the optimum incubation time which is at 36 hours. Prior to the optimization of protease production from soybean residue, the optimized paerameter were screened by conducting One-Factor-At-A-Time (OFAT) experiments. The parameter screened were inoculum size, substrate concentration and glucose concentration. The maximum protease activity by solid state fermentation was obtained at the optimized conditions at inoculum size of 3 % v/w, substrate concentration of 50 % w/w, and 5 % w/v of glucose concentration with 22 U/ml, 21.31 U/ml and 26.47 U/ml, respectively. Besides that, the kinetic parameter was also studied in this research where the value of Km and Vm obtained were 2 μmoles and 2.2 μmoles/min, respectively. The plotted graph of Lineweaver-Burk model obeyed the Michaelis-Menten kinetics. The small value of Km compared to Vm indicated a high affinity to form enzyme substrate complexs.