Journal Article

Thermophilic archaea activate butane via alkyl-coenzyme M formation

Musat, Florin, Tegetmeyer, Halina E., Meier, Dimitri V., Lechtenfeld, Oliver J., Laso-Pérez, Rafael, Widdel, Friedrich, Richter, Michael, Harding, Katie J., Krukenberg, Viola, Knittel, Katrin, Riedel, Dietmar, Wegener, Gunter, Richnow, Hans-Hermann, Adrian, Lorenz, Reemtsma, Thorsten

2016

Overview

The anaerobic formation and oxidation of methane involve unique enzymatic mechanisms and cofactors, all of which are believed to be specific for C 1 -compounds. Here we show that an anaerobic thermophilic enrichment culture composed of dense consortia of archaea and bacteria apparently uses partly similar pathways to oxidize the C 4 hydrocarbon butane. The archaea, proposed genus ‘ Candidatus Syntrophoarchaeum’, show the characteristic autofluorescence of methanogens, and contain highly expressed genes encoding enzymes similar to methyl-coenzyme M reductase. We detect butyl-coenzyme M, indicating archaeal butane activation analogous to the first step in anaerobic methane oxidation. In addition, Ca . Syntrophoarchaeum expresses the genes encoding β-oxidation enzymes, carbon monoxide dehydrogenase and reversible C 1 methanogenesis enzymes. This allows for the complete oxidation of butane. Reducing equivalents are seemingly channelled to HotSeep-1, a thermophilic sulfate-reducing partner bacterium known from the anaerobic oxidation of methane. Genes encoding 16S rRNA and methyl-coenzyme M reductase similar to those identifying Ca . Syntrophoarchaeum were repeatedly retrieved from marine subsurface sediments, suggesting that the presented activation mechanism is naturally widespread in the anaerobic oxidation of short-chain hydrocarbons. Anaerobic archaea enriched in thermophilic microbial consortia completely degrade butane by modifying mechanisms which were hitherto thought to be specific to methane metabolism. Environmental oxidation of non-methane hydrocarbons Research on the anaerobic oxidation of natural gas has largely been focused on methane as the most abundant constituent. It is less clear how short-chain alkanes—including ethane, propane, n -butane and iso -butane, which together make up about 20% of natural gas—are anaerobically metabolized. Sulfate-reducing bacteria are the only organisms known to date to anaerobically oxidize short-chain hydrocarbons. Gunter Wegener and colleagues identify an anaerobic thermophilic enrichment culture composed of dense consortia of archaea and bacteria that uses a pathway similar to anaerobic methane oxidation, which was previously thought to be specific for C 1 -compounds, to oxidize butane. Archaea activate butane, and reducing equivalents are channelled to sulfate-reducing partner bacteria. Similar consortia are detected in marine subsurface sediments, suggesting that this pathway may be widespread in nature.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 631/326/171 / 631/326/26/2527 / 631/45/320 / Alkylation / Anaerobiosis / Archaea - genetics / Archaea - metabolism / Archaeabacteria / Archaeal Proteins - chemistry / Archaeal Proteins - genetics / Archaeal Proteins - metabolism / Bacteria / Biocatalysis / Butanes - metabolism / Carbon monoxide / Dehydrogenases / Enzymes / Evolution, Molecular / Gases / Genes / Genomes / Humanities and Social Sciences / Hydrocarbons / Mesna - chemistry / Mesna - metabolism / Metabolism / Methane / Methanogenesis / Microorganisms / multidisciplinary / Natural gas / Observations / Oxidation / Oxidation-Reduction / Physiological aspects / Science / Sediments / Sulfate reduction / Sulfates - metabolism / Temperature