STATISTICAL AND KINETIC STUDIES OF ACID PROTEASE BY ASPERGILLUS SPP. ISOLATED FROM SOIL CONTAMINATED WITH ABATTOIR WASTE

Objective : Aim of the present investigation was to optimize the acid protease production from Aspergillus spp. through statistical method in solid state fermentation and to study the inhibitory enzyme kinetics. Methods: To fulfill above mentioned aim, seven solid substrates were screened though using PBD (Plackett-Burman Design) and concentrations of three significant were determined by using one of the Response surface methodologies (RSM), Box-Behnken design (BBD). Inhibitory enzymatic effects were carried by using previously developed models. Results : From PBD, wheat bran, soybean meal, and dried potato peel (DPP) were screened as major influencing nutritional factors for enzyme production. Better optimal values were determined by BBD as wheat bran: 8.841 g, soybean meal: 4.557 g, and DPP: 0.661 g with predicted protease activity as 817.83 U/g (±44.047 U/g). Linear, interactive, and quadratic effects of aforesaid substrates on enzyme activity were formulated by quadratic model through multiple regression model (R 2 Adj :Adjusted R square = 94.78%; R 2 Pre :Predicted R square = 98.13%). Partial substrate inhibition to crude acid protease activity was notified with casein concentration higher than 0.4 mmol and inhibitory constant, K N , was computed with previous developed mathematical models. Ratio of reaction rate constants, k 4 /k 2 , was found to be 0.233 that had confirmed partial casein inhibition to enzyme velocity. Improved activity and kinetics of caseinolysis make amicable for industrial applications. Conclusion: Quick optimization was performed with statistical methodology over conventional approach. Inhibitory enzyme kinetic studies were important for industrial applications of acid protease.