P139: Reprogramming Saccharomyces cerevisiae metabolism for optimal endogenous biodiesel production

Sustainable energy independence is a defining challenge of our time, and the production of transportation fuels from renewable resources is a promising contribution towards a solution. Biodiesel is an attractive target class due to its chemical properties and compatibility with existing infrastructure. Fatty acid ethyl esters (FAEEs) are produced endogenously in various organisms, and it has been shown that expression of a bacterial acyl-transferase in S. cerevisiae can lead to FAEE production from fatty acyl-CoA and ethanol.

In contrast to recent strategies to produce FAEE in S. cerevisiae through manipulation of fatty acid synthesis pathways, this work aimed to increase FAEE production compared to wild-type by increasing the cytosolic fatty acyl-CoA pool via disruption of the natural fatty acid degradation and recycling pathways.

First, to facilitate the production of fatty acyl-CoA, a completely heterologous pathway was constitutively expressed in S. cerevisiae. This pathway was constructed within a single plasmid that contained a thioesterase and fatty acyl-CoA synthetase from E. coli and an acyl transferase from Acenitobacter baylyi ADP1. This pathway was shown to produce FAEE when expressed in S. cerevisiae. Next, a series of gene deletion strains were designed to interrupt import of fatty acyl-CoA molecules of various length into the peroxisome in order to halt β-oxidation as well as to eliminate cytosolic fatty acyl-CoA binding proteins. Once constructed and transformed with the FAEE producing plasmid, our genetic environment has been shown to increase the production of FAEE compared to the wild-type.