Bioconversion of ferulic acid and vanillylmandelic acid to 4-vinyl guaiacol and vanillin mediated by Oenococcus oeni: towards sustainable flavor production

Introduction Conventional extraction of vanilla pods is both insufficient and costly, while chemical synthesis fails to satisfy natural labeling requirements. Biotechnological approaches therefore offer a promising alternative for sustainable, high-value aromatic compound production. Methods This study investigated the bioconversion of ferulic acid (FA), a hydroxycinnamic acid, and vanillylmandelic acid (VMA), a vanilloid, into vanillin and 4-vinylguaiacol (4VG) using three bacterial strains of Oenococcus oeni isolated from wine lees. Fermentation assays were performed with precursor supplementation at various concentrations and feeding strategies. Precursor consumption and aromatic compound production were monitored by Ultra-High-Performance Liquid Chromatography (UHPLC). For the highest-yielding fermentations, Downstream Processing (DSP) methods were applied to extract the target compounds. Results FA was metabolized into both 4VG and vanillin, while VMA was converted to vanillin via microbial catalysis. Maximum metabolic efficiency reached approximately 25.7% yield (referred to biocatalysis). Discussion These findings confirm the feasibility of biovanillin synthesis using O. oeni strains, supporting potential applications in natural flavor production and industrial scalability, and contributing to the development of more sustainable aromatic compound biotechnology.