Optimization of parameters for lipase production by Aspergillus niger NRRL-599 using response surface methodology

Abstract

Background and objective Lipases are characterized to catalyze precise chemical transformation. That is they have widespread applications in detergents, cosmetics, food, organics synthesis, and pharmaceutical industries. In recent years, the study and development of lipase production in solid state fermentation, also using sequential statistical strategy as optimization for some vital factors are gaining more attention. This may be attributed to several advantages using techniques such as simplicity of fermentation media, no need for complex machinery. Equipment and control system, compactness of fermentation vessel due to lower water volume, high yields, less energy needed, and lower capital. Materials and methods Aspergillus niger NRRL-599 strain was tested for lipase production using different agroindustrial wastes including wheat bran, wheat germ cake oil, jojoba cake oil, almond cake oil, and olive oil as substrates under solid state fermentation. For further optimization, lipase activity was studied using two sequential optimization. Results and conclusion Olive oil waste was the most suitable substrate for lipase production (125 U/ml). Using one variable at a time, maximum lipase activity (200 U/ml) and specific enzyme activity (357.1 U/mg) were recorded in the presence of 5% w/v olive oil, 48 h inoculum age, 4% v/v inoculum size after 14 days fermentation at 30°C. The screening of the seven physiological factors using Plackett–Burman design showed that only three variables; that is tween 80, moisture content, and inoculum age affected significantly lipase production. Optimization by Box–Behnken design resulted in the highest lipase activity (420 U/ml) in which the most effective variables were inoculum size, inoculum age, moisture content, and tween 80 1%.