Functional expression and characterization of five wax ester synthases in Saccharomyces cerevisiae and their utility for biodiesel production

<p>Abstract</p> <p>Background</p> <p>Wax ester synthases (WSs) can synthesize wax esters from alcohols and fatty acyl coenzyme A thioesters. The knowledge of the preferred substrates for each WS allows the use of yeast cells for the production of wax esters that are high-value materials and can be used in a variety of industrial applications. The products of WSs include fatty acid ethyl esters, which can be directly used as biodiesel.</p> <p>Results</p> <p>Here, heterologous WSs derived from five different organisms were successfully expressed and evaluated for their substrate preference in <it>Saccharomyces cerevisiae</it>. We investigated the potential of the different WSs for biodiesel (that is, fatty acid ethyl esters) production in <it>S. cerevisiae</it>. All investigated WSs, from <it>Acinetobacter baylyi </it>ADP1, <it>Marinobacter hydrocarbonoclasticus </it>DSM 8798, <it>Rhodococcus opacus </it>PD630, <it>Mus musculus </it>C57BL/6 and <it>Psychrobacter arcticus </it>273-4, have different substrate specificities, but they can all lead to the formation of biodiesel. The best biodiesel producing strain was found to be the one expressing WS from <it>M. hydrocarbonoclasticus </it>DSM 8798 that resulted in a biodiesel titer of 6.3 mg/L. To further enhance biodiesel production, acetyl coenzyme A carboxylase was up-regulated, which resulted in a 30% increase in biodiesel production.</p> <p>Conclusions</p> <p>Five WSs from different species were functionally expressed and their substrate preference characterized in <it>S. cerevisiae</it>, thus constructing cell factories for the production of specific kinds of wax ester. WS from <it>M. hydrocarbonoclasticus </it>showed the highest preference for ethanol compared to the other WSs, and could permit the engineered <it>S. cerevisiae </it>to produce biodiesel.</p