8-41: Biohydrocarbon fuel production in Saccharomyces cerevisiae using a synthetic production pathway: a proof in principle demonstration

The United States is the largest petroleum consumer in the world, needing to import greater than 50% of its oil to meet usage demands. One solution for assuaging this importation burden has been the development of biologically produced “drop-in-ready” hydrocarbon biofuels. These biohydrocarbon fuels can utilize existing infrastructure for storage and distribution and maintain a similar energy content to existing fuels, allowing for their direct use alongside traditional fossil fuels.  However, major hurdles, such as the lack of manufacturing capabilities from industrially relevant organisms and the relatively difficult large-scale exploitation of organisms with natural biohydrocarbon production pathways, have prevented their large-scale adoption.  To overcome these challenges we have demonstrated the proof-in-principle production of a biohydrocarbon fuel product from the industrially relevant yeast Saccharomyces cerevisiae.  Biohydrocarbon production was established through the expression of a synthetic pathway consisting of an aldehyde production unit encompassing a modified version of the bacterial luciferase gene cassette and the cyanobacterial Nostoc punctiforme aldehyde decarbonylase gene Npun R1711, which converts the supplied aldehyde to an alkane hydrocarbon.  Initial expression of this pathway in wild type S. cerevisiae resulted in approximately 10 μg/ml per unit OD₆₀₀ hydrocarbon production, with 7 μg/ml of the product retained within the yeast and 3 μg/ml excreted naturally into the media.  Computational modeling of S. cerevisiae’s metabolic pathways suggests that these production levels can be significantly enhanced by introducing genetic alterations that increase the metabolic flux through this novel exogenous pathway.