Two words: "Eat methane!"
"In a particularly special spot of mud, with just the right concentrations of methane and nitrates, dwells a particularly special little couple. They feed on methane and nitrates and they exhale pure nitrogen. They do not use oxygen. The duo constitutes a hitherto undiscovered cooperation between a bacteria and another type of single celled organism called an archaeon. Together, they break down methane without the use of oxygen or sulphates. They use nitrates instead. This was deemed impossible by other microbiologists who failed to find any such thing in over fifty years. Microbiologist and Vidi-winner Marc Strous, however, stubbornly persisted. He went on a deliberate search. He eventually struck gold in a spadeful of mud from the Twente Canal [in the eastern parts of the Netherlands].
For over a year, the microbes have been carefully nurtured in the laboratory of the Institute for Water and Wetland Research [of, apparently, the Radboud Universiteit Nijmegen]. They grew very slowly, despite all TLC, by about a single cell division each month. Yet this growth did result in sufficient quantities of material to allow for the establishment that the couple lived on methane and nitrate. The involvement of oxygen was ruled out and [the editors of] Nature were satisfied.
The researchers suspect that this type of methaan conversion in sweet water soils will be rather widespread. This means that the discovery is important to the understanding of the methane cycle on earth and, therefore, also for climate prediction scenarios. Methane is a strong greenhouse gas. In addition, the researchers hope to eventually be able to employ the symbiotic single-celled organisms for the purification of waste water."