Response surface modeling of vanillin production by Escherichia coli JM109pBB1

The increasing concern for healthy and nutritional products together with the high price of natural vanillin extracted from vanilla pods has stimulated the search for alternative means of natural vanillin production. The present work deals with a ferulic acid to vanillin bioconversion process using the recombinant strain Escherichia coli JM109pBB1. A set of batch bioconversion tests was carried out on aqueous ferulic acid solutions according to a 32 full factorial design selecting the starting biomass concentration (X0) and the initial ferulic acid concentration (S0) as independent variables. The experimental data were analyzed by the response surface methodology (RSM) using a quadratic model for predicting the optimal point. The best starting biomass concentration and initial ferulic acid concentration were found to be 380 mg L−1 and 2.95 mM, respectively. Under these conditions the model predicted a maximum vanillin concentration (Pv)(Pv) of 1.45 mM, a vanillin yield on consumed ferulic acid (Yv)(Yv) of 0.57 mM mM−1, a vanillyl alcohol on consumed ferulic acid (Yal) of 0.39 mM mM−1, a volumetric vanillin productivity (Qv)(Qv) of 0.124 mM h−1 and a specific vanillin productivity (qv)(qv) of 0.047 g g−1 h−1.