Microbial Transformation of Vanillin to Vanillic Acid with Recombinant Strain E.coli DH5α/pZJF1

Optimum fermentaion conditions for transformation of vanillin to vanillic acid with recombinant E.coli DH5α/ pZJF1, including inoculum age, inoculation volume, substrate concentration and the fermentation time, were studied. Vanillin and vanillic acid in the fermentation broth were determined with HPLC. Results showed that the optimum fermentation conditions were as follows: inoculum age 8 h to10 h, inoculation volume 1%, vanillin concentration 2.0 mg/ml and fermentation time 28 h. Under such conditions, the molar conversion yield of vanillic acid was up to 97.78%.