Abstract

Response surface methodology was applied to identify and optimize the medium composition for the cis-epoxysuccinate hydrolase production in recombinantEscherichia coli. Plackett-Burman design was used in the first step to evaluate the effects of 8 variables on the enzyme activity. CaCl₂, corn steep liquor and lactose were screened as significant factors and their concentrations were further optimized using response surface methodology based on 2³ full factorial rotatable central composite design. The optimum predicted medium for maximum expression of recombinant cis-epoxysuccinate hydrolase was found to comprise: 17.1 g/l Na₂HPO₄·12H₂O, 2.0 g/l KH₂PO₄, 0.5 g/l NaCl, 1.0 g/l NH₄Cl, 0.0111 g/l CaCl₂ and 0.5 g/l MgSO₄·7H₂O, 17.18 ml/l corn steep liquor and 9.74 g/l lactose, with a predicted enzyme activity of 35490 U/g biomass, which was very close to the experimental activity of 36318 U/g biomass resulting in 1.7-fold increment after optimization.

Key words: Medium, optimization, response surface methodology, cis-epoxysuccinate hydrolase, Escherichia coli.