Synthesis of customized petroleum-replica fuel molecules by targeted modification of free fatty acid pools in Escherichia coli.
Proceedings of the National Academy of Sciences
National Academy of Sciences
Freely available online through the PNAS open access option.
Biofuels are the most immediate, practical solution for mitigating dependence on fossil hydrocarbons, but current biofuels (alcohols and biodiesels) require significant downstream processing and are not fully compatible with modern, mass-market internal combustion engines. Rather, the ideal biofuels are structurally and chemically identical to the fossil fuels they seek to replace (i.e., aliphatic n- and iso-alkanes and -alkenes of various chain lengths). Here we report on production of such petroleum-replica hydrocarbons in Escherichia coli. The activity of the fatty acid (FA) reductase complex from Photorhabdus luminescens was coupled with aldehyde decarbonylase from Nostoc punctiforme to use free FAs as substrates for alkane biosynthesis. This combination of genes enabled rational alterations to hydrocarbon chain length (Cn) and the production of branched alkanes through upstream genetic and exogenous manipulations of the FA pool. Genetic components for targeted manipulation of the FA pool included expression of a thioesterase from Cinnamomum camphora (camphor) to alter alkane Cn and expression of the branched-chain α-keto acid dehydrogenase complex and β-keto acyl-acyl carrier protein synthase III from Bacillus subtilis to synthesize branched (iso-) alkanes. Rather than simply reconstituting existing metabolic routes to alkane production found in nature, these results demonstrate the ability to design and implement artificial molecular pathways for the production of renewable, industrially relevant fuel molecules.
This work was supported by a grant from Shell Research Ltd. and a Biotechnology and Biological Sciences Research Council (BBSRC) Industry Interchange Partnership grant (to J.L.).
This is the final version of the article. Available from National Academy of Sciences via the DOI in this record.
Data deposition: The synthetic nucleotide sequences reported in this paper have been deposited in GenBank database (accession nos. JQ901708, JQ901709, and JQ901710).
Vol. 110 (19), pp. 7636 - 7641
Place of publication