Mechanistic investigations on the pathway of n-alkane oxidation in anaerobic bacteria

• Applicant: Professor Dr. Heinz Wilkes
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: from 2009 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 71656632

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 15 years several denitrifying and sulphate-reducing bacteria capable of utilizing alkanes as sole source of carbon and energy have been isolated and characterized. Based on the identification of metabolites and studies with isotope labeled substrates a pathway for the complete oxidation of n-hexane to carbon dioxide in the denitrifying bacterium strain HxN1 has been proposed. In the initial activation reaction the n-alkane is added to the double bond of fumarate yielding (1-methylpentyl)succinate (MPS). MPS is further transformed via a sequence of enzyme reactions to a branched fatty acid (4-methyloctanoyl-CoA) which then is degraded by β-oxidation. Main goal of this project will be to obtain new insights into important mechanistic aspects of the proposed degradation pathway, and to contribute to a better understanding of possible fundamental differences in the biochemical mechanisms involved in n-alkane versus alkylbenzene oxidation. In particular, the stereochemistry of key metabolites will be established by stereoselective synthesis of authentic standards and rigid structure assignment of isolated metabolites. The substrate range of anaerobic hydrocarbon oxidizing bacteria will be characterized through co-transformation experiments with model substrates and crude oil.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1319: Biological Transformations without Oxygen: From the Molecular to the Global Scale
• Participating Persons: Professor Dr. Ralf Rabus; Professor Dr. Friedrich Widdel