Expression condition optimization of whole cell OPH activity based on surface response analysis.

In order to obtain high expression of whole cell OPH activity,we optimized the expression conditions.Plackett-Burman design was undertaken to evaluate the effects of eight factors.With statistic regression analysis,the significant factors affecting whole cell OPH activity were determined as follows: induction time,IPTG concentration and induction temperature.Box-Behnken design was used to optimize these three critical internal factors,and determine the optimum levels and the relationships among these factors.By quadratic regression model equation with Design Expert statistic methods,the optimal levels of the variables were determined as: IPTG-induction temperature 18.86 ℃,IPTG concentration 0.09mmol/L and induction time 8.74h.Under this condition,the predicted whole cell OPH activity was 27.829U/mL,and the experimental whole cell OPH activity was 27.8U/mL.