In This Issue

Plant metabolites can be beneficial to human health but are often difficult to produce and isolate in large quantities. Photosynthetic microbes provide a possible alternative for large-scale production of such plant compounds. Yong Xue et al. (pp. 9449–9454) engineered a photosynthetic microbe, the cyanobacterial strain Synechocystis sp. PCC 6803, to produce p-coumaric acid, a precursor of phenylpropanoid compounds, which possess antioxidant, antiviral, and anti-inflammatory properties. To create the strain, the authors introduced a tyrosine ammonia lyase gene from an actinomycete bacterium and deleted a polyphenol oxidase gene from the cyanobacterial genome. Whereas the original strain did not produce p-coumaric acid, the engineered strain produced 82.6 mg of p-coumaric acid per liter of growth medium. The p-coumaric acid was successfully extracted and purified from the cyanobacteria’s growth medium. According to the authors, the study suggests that the engineered cyanobacterial strain may provide a means to produce beneficial plant metabolites at rates higher than those at which the metabolites can be extracted from plants. — J.P.J.