Vanillin production from ferulic acid with Pseudomonas fluorescens BF13

Biotechnological processes for the production of vanillin from substrates of natural origin are getting increasing interest since the obtained flavor can be labeled as “natural” according to the EU legislation. In this work, we investigated the possibility of producing vanillin from ferulic acid, i.e., an abundant cell wall constituent in higher plants available from bran processing by-products, by employing resting cells of Pseudomonas fluorescens strain BF13 carrying an insertional inactivation of vdh gene and ech and fcs BF13 genes under the control of native Pfer promoter on a low copy number plasmid. Process parameters were optimized both for the biomass production phase (pH of the medium, catabolic induction) and the bioconversion phase (pH of the buffer, cells concentration, substrate concentration). Vanillin up to 8.46 mM could be obtained under optimized conditions after 24h of bioconversion with ferulic acid 10 mM as substrate, whereas the highest productivity (0.53 mmoles vanillin L-1 h-1) was obtained using ferulic acid 5 mM.