LIPASE PRODUCTION USING TERNARY FEEDSTOCKS: A CASE OF OPTIMIZATION USING MIXTURE DESIGN AND RESPONSE SURFACE METHODOLOGY.

ABSTRACT

Lipase is an important industrial enzyme that is produced from lipase sources through fermentation. This study investigated the effect of 3 independent variables namely: methanol, ethanol, and propanol, and their mutual interaction on lipase production from agro-wastes such as (watermelon seeds, banana peels, and waste cooking oil) products in a Box-Behnken design. Modeling was carried out using a mixture d-optimal design and response surface methodology (RSM). D-optimal was used to determine the optimum substrate mix. A quadratic model was obtained to predict the optimum substrate mix. The optimum substrate mix for mixture design was 2.755g watermelon seeds, 10.00g of banana peels, and 2.245g of waste cooking oil to give a lipase activity of 2130.99 u/gds (unit per gram dry substrate). RSM (Box-Behnken design) was then applied to optimize the substrate mix obtained from d-optimal and RSM gave the maximum value of lipase activity (3017.138 u/ gds). A Linear model was obtained to predict the lipase activity as a function of the 3 independent variables from RSM (Box-Behnken design). The optimum factor (inducer) variables for RSM were 1.991g of methanol, 1.685g of ethanol, and 1.954g of propanol to give a maximum lipase activity of 3017.138 u/gds. The developed mixture and RSM models described the fermentation with high accuracy as indicated by their high R2 values. Based on the statistical indices used for evaluation, RSM optimized the substrate mix and was found as an appropriate tool for optimization and modeling for the study.