Keith Joblin (left) and Frenchman Gerard Fonty.

Keith Joblin (left) and Frenchman Gerard Fonty.

Microbes discovered in the depths of a French lake may hold the key to dealing with the problem of belching cattle and sheep, source of a third of New Zealand's greenhouse gas emissions.

Dr Gerard Fonty, of Blaise Pascal University in Clermont-Ferrand in central France, discovered the methane-consuming micro-organisms in a nearby volcanic crater lake.

The 6000-year-old Lake Pavin is unusual in that its waters are in layers that do not mix, resulting in an anaerobic or oxygen-free zone in the bottom third of its 92m depth. Geochemists studying the lake noted that its deepest zone contained methane, but none reached the surface.

Fonty, whose field is the microbial ecology of lakes and other freshwater ecosystems, established that this was the result of a previously unknown microbe which had evolved to live on the methane produced in the sediment at the lake bottom.

Methane-consuming micro-organisms have been found before, but only in salty marine environments. These are the first from a freshwater source.

And while their natural habitat is cold, about 4C, Fonty and his team have succeeded in growing them in a laboratory at room temperature.

Fonty was able to recognise their potential significant because in the past his field of research was the microbiology of the rumen.

He is an old friend and colleague of Dr Keith Joblin, a senior scientist with AgResearch in Palmerston North and principal investigator for the pastoral Greenhouse Gas Consortium, the body funded by farmers and taxpayers which is looking for ways to suppress emissions of enteric methane.

Collaboration with Fonty and his colleagues is an important new avenue of that research, which had been confined to trying to block the methane from being produced in the first place.

But Joblin stresses that it is still in its early, fundamental phase.

"Everyone would love to do the quick and dirty experiment of introducing them to the rumen, but there is a lot we need to know first."

They are typical anaerobic organisms in that they grow and multiply relatively slowly and are fastidious, needing exactly the right environment.

"And they probably work together with other organisms," Joblin said

If introduced as immigrants, so to speak, to the teeming, complex microbial population of the rumen, would they survive and thrive?

Or might they prove antisocial? The biosecurity issues are serious. But so is climate change and methane is a potent greenhouse gas.