Screening of medium compositions for recombinant lipase production via two-level fractional factorial design / Aina Yasmin Daud and Wan Siti Atikah Wan Omar

The demand for lipase in the food and detergent industries is gradually increasing with the human population. Therefore, the production of recombinant lipase is an alternative to accommodate the high supply-demand caused. Large-scale enzymatic production aims to produce a maximum yield with a minimum, medium cost. An experimental design using a two-level fractional factorial design (2k-1 FFD) was conducted at a laboratory scale. The experiment was carried out to measure and screen the effect of five medium components as the factors, namely ammonium sulphate ((NH4)2SO4), glycerol, yeast extract, monopotassium dihydrogen phosphate (KH2PO4) and dipotassium phosphate (K2HPO4). The factors were exploited respectively at low and high-level parameter ranges in g/L, (NH4)2SO4 7.00-14.00; glycerol 17.50 – 35.00, yeast extract 10.00 – 20.00; KH2PO4 1.00-2.00; K2HPO4 8.25-16.50). The combination of experimental design with 25-1 fractional factorial design reflected 16 shake flasks of submerged fermentation of recombinant E. coli (rE. coli) harbouring recombinant lipase. Responses of lipase and total protein yield were obtained, and the interaction between the five factors was investigated in this study. In the finding for the lipase concentration, (NH4)2SO4 and K2HPO4 were significant contributing factors, while only K2HPO4 was found to contribute to the total protein. However, the Pareto plot displayed that the K2HPO4 and (NH4)2SO4 have different influences on lipase production. Meanwhile, K2HPO4 showed a positive impact on both lipase and total protein concentration. In the study, the maximum lipase concentration was 5.56 mg/ml with lipase activity 7.58 x 10-2 μmol/min/ml and maximum specific lipase activity was 3.01 x 10-2 μmol/min/mg. While for the total protein, the highest concentration was 1.28 mg/ml.