Knowledge gap closed in our understanding of degradation of ethane
Single-celled organism that oxidises ethane on the seabed
With a share of up to ten percent, ethane is the second most common component of natural gas and is present in deep-seated land and marine gas deposits all around the world. Up to now, it was unclear how ethane is degraded in the absence of oxygen. A team of researchers from the Helmholtz Centre for Environmental Research (UFZ) have solved this mystery, after more than fifteen years of research work in cooperation with colleagues from the Max Planck Institute for Marine Microbiology in Bremen. In a microbial culture obtained from Gulf of Mexico sediment samples, the scientists have discovered an archaeon that oxidises ethane. The single-celled organism has been named Candidatus Argoarchaeum ethanivorans, which literally means 'slow-growing ethane eater'. In an article now published in the journal Nature, the researchers describe the metabolic pathway of ethane degradation.
The researchers had to demonstrate a great deal of patience in solving the mystery of anaerobic degradation of saturated hydrocarbons. In 2002, UFZ microbiologist Dr Florin Musat, who at that time was conducting research at the Bremen-based Max Planck Institute for Marine Microbiology, received a sediment sample originating from the Gulf of Mexico. The sample had been collected from natural gas seeps at a water depth of more than 500 metres. It took over ten years of cultivation effort to obtain sufficient quantities of the culture containing the archaeon -- as the basis for detailed experiments to decode the structure and metabolism of the microbial community. During his regular measurements, Florin Musat recognized that oxidation of ethane was coupled to reduction of sulphate to hydrogen sulphide. "For quite a long time, we thought that the anaerobic degradation of ethane was carried out by bacteria in a similar way to the degradation of butane or propane, but we were unable to identify metabolic products typical for a bacterial mechanism of oxidation," says Musat.
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