Newcastle University

A research group in the School of Chemistry led by Professor Bernard Golding with the aid of several collaborators in Germany and funded by the German Research Foundation (DFG) have elucidated the mechanism of oxygen-free microbial attack on hexane, a representative saturated hydrocarbon. The results are published in the prestigious journal Angewandte Chemie (International Edition) R Jarling, M Sadeghi, M Drozdowska, S Lahme, W Buckel, R Rabus, F Widdel, B T Golding, and H Wilkes, 'Stereochemical investigations reveal the mechanism of the bacterial activation of n-alkanes without oxygen'; article published online 30 Nov 2011; DOI: 10.1002/anie.201106055.

The pathway discovered may represent an evolutionary ancient mode of microbial hydrocarbon utilisation, which was originally widespread, but upon the rise of atmospheric oxygen was confined to subsurface habitats including petroleum reservoirs and the deep sea. Saturated hydrocarbons (alkanes) are widespread natural organic compounds that are the main constituents of fossil organic matter and play a fundamental role in the global carbon cycle. They are generated by thermal reactions deep within sedimentary basins and, over geologic timescales, may accumulate in petroleum reservoirs. Hydrocarbons represent a major substrate pool for microorganisms (anaerobes) living in the subterranean oxygen-free biosphere. The degradation of hydrocarbons by these anaerobes requires attack on a strong carbon-hydrogen bond, which is performed by a 'radical enzyme' using fumaric acid in place of oxygen. The destruction of oil spills also depends on the activity of such anaerobes. Whereas biodegradation of hydrocarbons with oxygen is long known and understood in much detail, the oxygen-independent process was poorly understood until the present Newcastle-German study. Understanding how radical enzymes work could lead to new industrial processes utilising hydrocarbon feedstocks.