Production of biovanillin from wheat bran

The fine specialty chemicals production from agro-industrial by-products such as cereal bran is a topic of high interest in wheat-producing countries. In this work, the possibility of obtaining vanillin from bioconversion of ferulic acid derived from enzymatic hydrolysis of wheat bran was explored. Freely available ferulic acid was first obtained through wheat bran hydrolysis by using commercially available, technical-grade enzyme preparations. Then, resting cells of an engineered E. coli strain, JM109(pBB1), containing the genes responsible for conversion of ferulic acid into vanillin, were used to transform ferulic acid available in the hydrolyzed mixture into vanillin. A vanillin molar yield of 50% was obtained, but most of the vanillin produced was reduced to vanillyl alcohol. The purification of the hydrolyzate with a ionic exchange resin to remove most of the carbohydrates allowed to obtain both higher bioconversion yields (up to 70%) and lower vanillin reduction. This is the first work in which vanillin is produced from ferulic acid obtained through wheat bran hydrolysis. The results obtained demonstrate the potential application of the proposed strategy in vanillin biosynthesis from agro-industrial by-products.