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