Biotransformation of corn bran derived ferulic acid to vanillic acid using engineered Pseudomonas putida KT2440.

Ferulic acid is a fraction of the phenolics present in cereals such as rice and corn as a component of the bran. Substantial amounts of waste bran are generated by the grain processing industry and this can be valorized via extraction, purification and conversion of phenolics to value added chemical products. Alkaline alcohol based extracted and purified ferulic acid from corn bran was converted to vanillic acid using engineered Pseudomonas putida KT2440. The strain was engineered by rendering the vanAB gene nonfunctional and obtaining the mutant defective in vanillic acid metabolism. Biotransformation of ferulic acid using resting Pseudomonas putida KT2440 mutant cells resulted in more than 95 ± 1.4% molar yield from standard ferulic acid; while the corn bran derived ferulic acid gave 87 ± 0.38% molar yield. With fermentation time of less than 24 h the mutant becomes a promising candidate for the stable biosynthesis of vanillic acid at industrial scale.