Australasian Science: Australia's authority on science since 1938

Methane-Eating Microbe

By Stephen Luntz

A microbe has been identified that breathes nitrate rather than oxygen and turns methane into carbon dioxide.

It is suspected of playing a substantial role in reducing atmospheric methane and may have potential for fighting climate change.

Methane is a far more potent greenhouse gas than carbon dioxide, with 25 times the warming effect over a 100-year period. This has led to a search for life forms capable of mitigating the damage. The new discovery is not the first such find, but it operates differently from previous discoveries.

Researchers from the University of Queensland’s Advanced Water Management Centre and the Australian Centre for Ecogenomics didn’t have to go to an exotic location to find the microbe. They inoculated a bioreactor with samples take from the University of Queensland’s lake and some wastewater, and supplied it with methane and nitrate to see what would happen. The result was published in Nature.

“For many years the thermodynamics and biochemistry have been around to suggest something like this should exist,” says Dr Gene Tyson. “A Dutch group found a microbe that does something similar, but does it in a different way.”

While we don’t yet know how significant the new discovery is in the wider environment, Tyson calls the ease of discovery “the primary premise we have that it plays an important role in the environment. If it was found in a place like this it is likely to be found in lots of similar environments.”

Such life forms are only being found now, Tyson says, because it is only recently that microbial ecologists have come to recognise that “what we grow in the lab is a small proportion of what is out there. We could have known this existed because we can see it under a microscope, but not known what it is because we couldn’t grow it.” DNA and RNA identification techniques are changing this.

With nitrate pollution from excessive fertiliser use damaging many waterways, the microbe may be playing a big part in stopping emissions already, as well as linking the nitrogen and carbon cycles.

Co-author Prof Zhiguo Yuan is working to explore circumstances in which the discovery can be put to work.