Biovanillin Production Research Articles

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.

Functional analysis of the vanillin pathway in a vdh-negative mutant strain of Pseudomonas fluorescens AN103

The catabolism of ferulic acid in Pseudomonas fluorescens AN103 proceeds via vanillin, vanillic acid, and protocatechuic acid. The inactivation of the vanillin dehydrogenase of P. fluorescens AN103, which catalyzes the oxidation of vanillin to vanillic acid, was pursued as an approach for developing a biotechnological process for the production of biovanillin. In order to inactivate the vdh gene, a plasmid construction was made in which an omega element conferring resistance to kanamycin (ΩKm) was inserted into a truncated vdh gene (Δ vdh). Subsequently, this construct was used to replace the functional vdh gene with the disrupted Δ vdhΩKm in P. fluorescens AN103 by homologous recombination using a triparental mating approach. The successful inactivation of the gene was confirmed both by spectrophotometric and specific activity staining of crude cell extracts after native electrophoresis. However, inactivation of the vdh gene in P. fluorescens AN103 did not result in the expected accumulation of vanillin in media despite the absence of other enzymes exhibiting vanillin dehydrogenase activity. Further characterization showed that the P. fluorescens AN103 vdhΩKm mutant was unable to grow on vanillin as well as on ferulic acid as a sole carbon source. The inability to degrade ferulic acid was attributed to the lack of 4CL activity resulting from the inactivation of the vdh gene.