Enhanced production of xylanase by recombinant Escherichia coli DH5α through optimization of medium composition using response surface methodology

Abstract

The effect of medium composition on the production of intracellular xylanase by recombinant Escherichia coli DH5α was studied in shake flask culture. The medium was optimized using response surface methodology (RSM) based on two-level fractional factorial design (2FFD) and central composite design (CCD). Initially, significant factors of the medium composition affecting xylanase production were screened using 2FFD, where the variables consisted of glucose, diammonium hydrogen phosphate [(NH4)2HPO4], dipotassium hydrogen phosphate (K2HPO4), potassium dihydrogen phosphate (KH2PO4) and magnesium sulphate (MgSO4). The significant variables from the 2FFD [(NH4)2HPO4, K2HPO4 and MgSO4] were selected further for CCD to improve the final xylanase yield. The optimum medium composition to achieve maximum xylanase activity was 15 g L−1 glucose, 10 g L−1 (NH4)2HPO4, 18 g L−1 K2HPO4, 3.5 g L−1 KH2PO4 and 1.5 g L−1 MgSO4, with a final xylanase activity of 2,649 U mL−1. Verification experiments confirmed the validity of the proposed model, which led to an increase in xylanase production by about 74% as compared to non-optimized medium (1,526 U mL−1).