RESPONSE SURFACE METHODOLOGY OPTIMIZATION OF PROCESS PARAMETERS FOR LIPASE PRODUCTION BY RHIZOPUS ARRHIZUS
HRISTINA STRINSKA1*, BORIANA ZHEKOVA1, VALENTINA DOBREVA2, GEORGI DOBREV1
1 – Department of Biochemistry and Molecular Biology, Technological Faculty, University of Food Technologies, Plovdiv, Bulgaria
2 – Engineering Ecology, Faculty of Economics, University of Food Technologies, Plovdiv, Bulgaria
*Corresponding author: hstrinska@gmail.com
Keywords: Rhizopus arrhizus; lipase; submerged fermentation; response surface methodology; optimal composite design
Abstract: The initial pH of the nutrient medium and the temperature of cultivation had a major impact on lipase biosynthesis by Rhizopus arrhizus.
The optimal values of the factors were defined by using response surface methodology. Planned mathematical design was carried out and regression model was developed. It was used for prediction of the optimal values of independent variables – 30°C for cultivation temperature and 7.0 for initial pH of fermentation medium. The maximum predicted activity from the design was 4749.91 U. dm-3. The mathematical model was characterized with high value of the coefficient of determination R2=95. 75%, which showed high correlation with the experimental results.
Three consecutive experiments at the predicted optimal values of the factors were carried out. A mean value of 4658.45 U.dm-3 for lipase activity was achieved, which experimentally confirmed the results obtained from the mathematical model.