Development of a high‐efficiency trans‐cinnamic acid bioproduction method by pH‐controlled separation technology

BACKGROUND Trans‐cinnamic acid (t‐CA) and its derivatives have been shown to be antioxidant and antibacterial, and can be used in food additives and flavors. However, a traditional t‐CA production via chemical synthesis with a condensation reaction may not be suitable for its application in the pharmaceutical and food fields as it is not a ‘green’ route. This study investigated the bioconversion of l‐phenylalanine (l‐phe) to t‐CA using engineered whole‐cell Escherichia coli BL21(DE3) expressing phenylalanine ammonia‐lyase (PAL, EC 4.3.1.5) as a biocatalyst. To prevent product inhibition, an in situ reaction and separation of t‐CA was performed using a pH‐controlled biotransformation strategy. RESULTS A coupling reaction and separation system based on pH adjustment was proposed for improving the bioproduction of t‐CA. Using this process, 39.61 g L−1 t‐CA was bioproduced from 40 g L−1 of l‐phe in 8 h and a high purity (>98%) of t‐CA product was achieved directly without additional purification. CONCLUSION The bioprocess developed in this study is a highly efficient method for the bioproduction of t‐CA and, therefore, offers a promising alternative route for t‐CA production. © 2019 Society of Chemical Industry