This project is part of the DFG Priority Programme 1319: 'Biological transformations of hydrocarbons without oxygen: from the molecular to the global scale'
Background Alkanes are the main constituents of crude oil and various petroleum products. Their biodegradation in anoxic natural environments such as contaminated aquifers or petroleum reservoirs plays an important role in the global carbon cycle. During the last 20 years several denitrifying and sulphate-reducing bacteria capable of utilising alkanes as sole source of carbon and energy have been isolated and characterised. Based on the identification of metabolites and studies with isotope labeled subtrates we have proposed a pathway for the complete oxidation of n-hexane to carbon dioxide in the denitrifying bacterium strain HxN1. In the initial activation reaction the n-alkane is added to the double bond of fumarate yielding (1-methylpentyl)succinate. This intermediate is further transformed via a sequence of enzyme reactions to a branched fatty acid which then is degraded by β-oxidation. Investigations within the framework of this project will contribute to an improved understanding of the biogeochemical mechanisms of anaerobic biodegradation of hydrocarbons.