Bioconversion of ferulic acid obtained from wheat bran into vanillin

In this work the possibility of producing vanillin through microbial bioconversion from ferulic acid obtained from the enzymatic hydrolysis of wheat bran has been explored. The biocatalyst employed was Escherichia coli JM109/pBB1, a recombinant strain containing the genes from Pseudomonas fluorescens BF13 for the transformation of ferulic acid into vanillin. The substrate of the bioconversion, performed with resting cells of E.coli JM109/pBB1 grown on LB rich medium, was the crude hydrolizate obtained from wheat bran or a buffer containing ferulic acid recovered from the crude matrix with different methods, as adsorption on ion exchange resins, liquid-liquid extraction and solid phase extraction; these operations allowed the selective recovery of ferulic acid from carbohydrates present in the hydrolizates, thus obtaining an aqueous phase rich in reducing sugars. The removal of reducing sugars allowed to obtain higher bioconversion yields. The results of this work showed that vanillin can be obtained at interesting yields from ferulic acid extracted from wheat bran.