PETROX - Petroleum Alkane oxidation by Anaerobic Archaea

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Petroleum n-alkanes are a major compound class in crude oil, and their abundance determines the oils’ fluidity and exploitability. Petroleum alkanes are also an attractive energy and carbon source for aerobic and anaerobic microorganisms. This proposal aims at resolving the functioning of the anaerobic, petroleum-alkane oxidizing archaea using recently obtained, unique cultures of Candidatus Alkanophaga (a relative of the ANME-1 archaea) and Candidatus Ca. Cerberiarchaeum (a member of the deep-branching Hadarchaea). Both organisms grow with Thermodesulfobacteria as sulfate-reducing partners. The archaea activate mid- to long-chain n-alkanes (C6-C20) with alkyl coenzyme M reductases, divergent variants of methyl coenzyme M reductase, the enzyme known to generate or capture methane. The archaea are likely key players in subsurface oil transformations and have intriguing uncharted biochemistry. In the presented project PETROX, we will resolve the functioning of petroleum alkane degradation in archaea. Centralized around a 31/2-year PhD project, we will (I) optimize the growth conditions from both cultures and determine the strategies of the archaea and their partner to adapt to the solvent-like substrate (II) resolve the molecular basis of petroleum alkane activation via ACR using native crystallization (III) assess the interaction of the archaea with their bacterial partners in physiological experiments, stable isotope probing experiments and ultrastructural analyses. We combine our expertise in anaerobic hydrocarbon microbiology and biochemistry, and collaborate with experts in visualization techniques. This project will provide fundamental knowledge on the functioning of members from the subsurface microbiome, the enzyme mechanistic to activate long-chain alkanes and syntrophic interactions.