High-level production of trans-cinnamic acid by fed-batch cultivation of Escherichia coli

Trans-cinnamic acid is a phenylpropanoid that is widely used in cosmetics, anti-bacterial compounds, anticancer, and flavoring agents. Previously, we succeeded in the generation of L-phenylalanine-high producing Escherichia coli strain by metabolic engineering of the L-phenylalanine biosynthesis pathway. Using this engineered strain, in this study, we developed an E. coli platform for the enhanced production of trans-cinnamic acid that can be generated from L-phenylalanine by phenylalanine ammonia-lyase (PAL)-mediated deamination reaction. To increase the production titer of trans-cinnamic acid, three different promoters and four different nutrient solutions were examined and, using the optimized system (gene expression under Trc promoter and supplementation of casamino acid), we achieved the production of trans-cinnamic acid as high as 697 mgL(-1) in shake flask cultivation. Finally, pH-stat fed-batch fermentations were performed in a lab-scale (2 L) bioreactor with three different feeding solutions (glucose, yeast extract, and casamino acid). When casamino acid was supplied as feeding solution, the production of trans-cinnamic acid as high as 6.9 gL(-1) was achieved.