The Nijmegen microbiologist Mike Jetten has his own ‘most wanted list’. It isn't full of criminals. Instead, it features nine microbes which have not been discovered yet but which he thinks ought to exist. These microbes are the driving force behind chemical reactions which researchers know to happen in nature. As a result of their important role in nature and potential benefits in biotechnology, scientists are putting a lot of effort into tracking them down.
Together with colleagues from Radboud University Nijmegen and the Max Planck Institute for Marine Microbiology, Jetten discovered 'phantom microbe' number eight. It lay hidden in mud samples taken from the Twentekanaal ten years previously. The discovery is described in a scientific journal, PNAS. The researchers have named the microbe Methanoperedens nitroreducens, which roughly translates as 'methane-eating nitrate reducer'. The microbe, an archaeon, removes the oxygen from nitrates and uses it to ‘oxidise’ methane to form CO2. The electrons which are released in this last step attach themselves to iron and manganese atoms. Other microbes can then ingest these ‘charged’ manganese and iron atoms for extra energy.
Flow of methane
Methane is a very powerful greenhouse gas. Its effect on our atmosphere is 100 times stronger than that of carbon dioxide. Clearly, the balance between methane production and reduction is very important. The newly discovered microbe uses methane to make iron available for other micro-organisms in ‘edible’ form. As a result, it not only reduces methane levels but also creates an essential flow of energy in the sediment. 'We used to think that once iron and manganese got into the environment, they would always be there. But it turns out they're not as permanent as we thought', says Jetten in the De Volkskrant newspaper.
The researchers are now examining whether the newly discovered archaea can be used for wastewater treatment. One of the problems in the current treatment processes is the removal of nitrates. At present, this is generally achieved by adding extra methanol.