Application of half-fractional factorial design (H-FFD) and response surface methodology to high-level expression of lipase in Escherichia coli

Microbial lipases are widely used for biotechnological applications. In this study we have isolated the lipase and lipase specific foldase genes of a local strain bacterium which identified as Pseudomonas sp. and cloned into a dual expression vector PACYCDuet-1. The lipase was composed of 936 bp which encoded 311 amino acids and the lipase specific foldase gene consisted of 1008 bp which encoded 336 amino acids. In order to medium optimization formaximum lipase production, 25-1 half-fractional factorial design (H-FFD) was employed in triplicate at two levels for initial screening of the factors, potentially influencing the response.Subsequently, the selected factors were subjected to response surface methodology (RSM) with a four factor-five coded level central composite design (CCD), using Quadratic model for obtaining the optimum values for the factors. The adequacy of the calculated model wasconfirmed by the coefficient of determination (R2) and F value of 0.92 and 13.02, respectively. The optimized condition for enzyme expression obtained in a medium containing glucose (10 g/L), tryptone (5 g/L) NaCl (5 g/L) and yeast extract (20 g/L). Under the optimal condition the yield of active lipase production was enhanced up to 3-fold.

کلیدواژه ها:

Lipase ، Response surface methodology ، Half-fractional factorial design ، Optimization ، Pseudomonas sp