Identification of variables and value optimization for optimum lipase production by Bacillus pumilus RK31 using statistical methodology

In an effort to optimize the medium components, the statistical methodology was applied to achieve the optimum lipase production under shake flask conditions. The study was conducted in three steps on newly isolated Bacillus pumilus RK 31. In the first step, 12 different variables viz., Glucose, Olive oil, Yeast extract, Peptone, Tween 80, KH2PO4, MgSO4, NaNO3, CaCl2, Temperature, pH and Inoculum size were used to identify the most significant variables affecting lipase production using Plackett–Burman statistical design. Variance analysis showed that Olive oil, Tween 80 and KH2PO4 played significant role in lipase production. In the second step, the values of the above-identified three variables were optimized by central composite design using three-level-three-factor approach. The optimum values of Olive oil, Tween 80 and KH2PO4 were found to be 10.0 ml/l, 5.0 ml/l and 8.0 g/l, respectively. KH2PO4 was found to be responsible for maximum lipase production of 5.59 IU/ml, experimental and 5.03 IU/ml, predicted. In the third step, the optimum predicted values of the three factors and lipase production were verified by experimental approach. The amount of lipase produced in the designated medium was in agreement with that of predicted values by statistical method.