Application of Plackett-Burman Experimental Design for Lipase Production by Aspergillus niger Using Shea Butter Cake

Plackett-Burman design was used to efficiently select important medium components affecting the lipase production by Aspergillus niger using shea butter cake as the main substrate. Out of the eleven medium components screened, six comprising of sucrose, (NH4)2SO4, Na2HPO4, MgSO4, Tween-80, and olive oil were found to contribute positively to the overall lipase production with a maximum production of 3.35？U/g. Influence of tween-80 on lipase production was investigated, and 1.0% (v/w) of tween-80 resulted in maximum lipase production of 6.10？U/g. Thus, the statistical approach employed in this study allows for rapid identification of important medium parameters affecting the lipase production, and further statistical optimization of medium and process parameters can be explored using response surface methodology. 1. Introduction Lipases (E.C. 3.1.1.3) are enzymes that primarily catalyze the hydrolysis of triacylglycerols and show enormous potentials in catalyzing the synthesis of esters through transesterification, thioesterification, and aminolysis in nonaqueous media [1, 2]. Lipases have been utilized in different industrial processes including detergent formulation, flavor enhancement, treatment of fatty effluents, production of biosurfactants, biopharmaceutical formulations, and biodiesel production [3, 4]. Agroindustrial residues are continuously being generated in vast quantity especially in developing countries and their disposal is associated with several environmental problems [5]. Utilization of these agroresidues and byproducts of agroindustries as nutrient sources for microbial lipase production may reduce the final enzyme production cost, which is one of the major challenges affecting the large-scale production [6, 7]. Some of the agricultural residues reported in the literature for lipase production include brans (wheat, rice, soybean, and barley), oil cakes (soy, olive, gingelly, and babassu), and bagasse (sugarcane) [8, 9]. Lipases can be produced by animals, plants, and microorganisms. However, microbial lipases have been extensively studied due to their interesting characteristics such as stability in organic solvents, action under mild conditions, and high substrate specificity [2, 10]. Fungi are among the best adapted species in the utilization of agricultural residues based on their ability to grow on surfaces of various substrates and penetrate into the interparticle spaces of the solid substrates [11]. Additionally, tolerance to minimal water condition renders fungi to be more efficient in the bioconversion of several renewable