Optimization of culture conditions to enhance cis-epoxysuccinate hydrolase production in Escherichia coli by response surface methodology

The effect of culture conditions on the cis-epoxysuccinate hydrolase (CESH) production in recombinant Escherichia coli BL21 was investigated using response surface methodology (RSM), which was based on rotatable central composite design. The optimization of seed conditions consisted of a total of 13 experiments involving 4 star points and 5 replicates at the central points, while the optimization of induction conditions consisted of a total of 31 experiments involving 8 star points and 7 replicates at the central points. The optimum predicted culture conditions for maximum expression of recombinant CESH were found to be comprised of 11.75 h seed age, 4.13% (v/v) inoculation level, OD600 0.2 induction-starting time, 2.53% (w/v) lactose, 24.29 °C post-induction temperature and 27.56 h post-induction time, with a predicted CESH activity of 40,460 U/g, which was very close to the experimental CESH activity of 40,129 U/g resulting in 4.6-fold increment after optimization.