Direct Conversion of CO2 to alpha-Farnesene Using Metabolically Engineered Synechococcus elongatus PCC 7942

Abstract

Direct conversion of carbon dioxide (CO2) to value-added chemicals by engineering of cyanobacteria has received attention as a sustainable strategy in food and chemical industries. Herein, Synechococcus elongatus PCC 7942, a model cyanobacterium, was engineered to produce alpha-farnesene from CO2. As a result of the lack of famesene synthase (FS) activity in the wild-type cyanobacterium, we metabolically engineered S. elongatus PCC 7942 to express heterologous FS from either Norway spruce or apple fruit, resulting in detectable peaks of alpha-farnesene. To enhance alpha-farnesene production, an optimized methylerythritol phosphate (MEP) pathway was introduced in the farnesene-producing strain to supply farnesyl diphosphate. Subsequent cyanobacterial culture with a dodecane overlay resulted in photosynthetic production of alpha-farnesene (4.6 +/- 0.4 mg/L in 7 days) from CO2. To the best of our knowledge, this is the first report of the photosynthetic production of alpha-farnesene from CO2 in the unicellular cyanobacterium S. elongatus PCC 7942.