Production of Cinnamaldehyde through Whole-Cell Bioconversion from -Cinnamic Acid Using Engineered .

Cinnamaldehyde (CAD) has various applications in foods and pharmaceuticals and has gained prominence as a potent nematicide in agricultural research owing to its nematicidal activity. However, conventional methods of CAD production, including extraction from plants or organic chemical synthesis, are environmentally hazardous and limit its utilization for downstream applications. Here, we engineered as a whole-cell biocatalyst for the efficient bioconversion of -cinnamic acid (-CA) into CAD. An expression module of carboxylic acid reductase was constructed for the conversion of -CA to CAD. Additionally, the putative dehydrogenase-related genes (, , and 1176) responsible for the conversion of CAD to cinnamyl alcohol were deleted from the engineered strain to prevent the loss of CAD. Furthermore, as the conversion is NADPH-dependent, we investigated the conversion efficiency by exchanging the putative promoter region for the gene, which encodes glucose-6-phosphate dehydrogenase, with a strong promoter to increase the NADPH pool. Finally, a bioconversion platform using as a whole-cell biocatalyst was developed by deleting the gene, which is involved in the reverse conversion of CAD to -CA. Taken together, a 100% conversion yield of 1.1 g/L CAD from 1.2 g/L -CA was obtained within 30 min.