Identification of a Gene Involved in the Biosynthesis of 1-Alkenes in the Cyanobacterium Synechococcus sp. PCC 7002

Carbon dioxide emissions and the increasing demand for transportation fuels are promoting the development of renewable alternatives to fossil fuels. Cyanobacterial hydrocarbons are a promising alternative because the direct conversion of sunlight and carbon dioxide to lipids will by-pass recalcitrant intermediates found in terrestrial biomass. It has been reported that the cyanobacterium Synechococcus sp. PCC7002, which is among the fastest growing of all cyanobacteria, synthesizes two alkenes of unknown structure but nothing was known about their biosynthesis. In this study, we characterized the lipid profile of Synechococcus sp. PCC7002 and demonstrate the involvement of a gene in the biosynthesis of two C19 alkenes. The gene encodes a large multi-domain protein with homology to Type I polyketide synthases, suggesting a new route for hydrocarbon biosynthesis from fatty acids via an elongation-decarboxylation mechanism. The combinatorial nature of polyketide synthesis raises the possibility of using this type of genes to produce a wide range of industrially relevant 1-alkenes and high value chemical building blocks.