Photoautotrophic production of p-Coumaric acid using genetically engineered Synechocystis sp. Pasteur Culture Collection 6803

Abstract

In view of the environmental problems associated with climate change and greenhouse gas emissions, the potential of carbon sequestration has emerged as a research hotspot. Cyanobacteria can use solar energy and carbon dioxide to produce organic molecules bypassing the need for carbohydrate feedstock. This valuable trait has spearheaded its use in the field of bioproduction and ultimately metabolic engineering. As a natural phenolic compound, p-Coumaric acid is widely present in plants. Like other secondary metabolites, they are mainly produced to protect the plants against stress. p-Coumaric acid has many antioxidant and anti-inflammatory properties which are of importance to the pharmaceutical, food, cosmetic, and agricultural industries as precursors of active ingredients.In this study, we report the heterologous expression of the phenylalanine ammonia-lyase (PAL) and the cinnamic acid 4-hydroxylase (C4H) exogenous genes under the Pcpc560 promoter in the cyanobacteria Synechocystis sp. PCC6803. After 7 days of photoautotrophic growth, 0.8 mM of p-Coumaric acid was produced. To further increase production titer, we knocked out the Synechocystis sp. PCC6803 gene encoding the arogenate dehydrogenase which led to the production of 1.2 mM p-Coumaric acid after 7 days of photoautotrophic growth. Our work provides more insight into the double-step phenylpropanoid biosynthesis pathway contributing to extend the knowledge of the cyanobacteria's ability to produce plant secondary metabolites directly from carbon dioxide.