Direct valorization of agricultural byproducts to vanillin by a synergistic Komagataella phaffii co-culture system

The annual abundance of lignocellulosic agricultural byproducts poses a significant environmental burden. Leveraging this underutilized biomass to produce high-value, food-grade products represents a promising strategy for diversifying food ingredient sources and advancing the principles of the circular bioeconomy.

Here, a novel Komagataella phaffii co-culture system was developed for integrated xylan hydrolysis and vanillin biosynthesis. In the upstream xylan hydrolysis module, overexpression of a novel multi-modular bifunctional xylanase/feruloyl esterase enabled the direct hydrolysis of xylans in agricultural byproducts to release ferulic acid (FA), thereby providing precursors for the downstream vanillin synthesis module. In the downstream module, FA was converted to vanillin via heterologous expression of feruloyl-CoA synthetase (FCS) and enoyl-CoA hydratase/aldolase (ECH). Subsequent optimization of strain inoculation ratios and carbon source composition in the co-culture system increased the titer of vanillin and its derivatives to 2.63 mM, achieving a 47.90% molar conversion rate from ultrafine-grinding corn cob (UGCC).

This study establishes a scalable platform for synthesizing aromatic compounds from low-cost lignocellulosic feedstocks, offering a strategic blueprint for valorizing agricultural residues.