Methane-metabolising microorganisms discovered

Scientists from The University of Queensland have discovered two new microorganisms which are said to play an unknown role in greenhouse gas emissions and consumption. Their research, led by Associate Professor Gene Tyson, has been published in the journal Science.

“For thousands of years, billions of tonnes of carbon have been stored in the Northern Hemisphere in the form of permafrost,” said Dr Tyson, the deputy head of the Australian Centre for Ecogenomics at UQ. “Now with global warming, these vast areas are thawing.

“A large fraction of the carbon being released is methane — a potent greenhouse gas with about 25 times the warming capacity of carbon dioxide. Once thawed, the organic matter in the permafrost allows microbes to flourish — and it is their activity that produces the methane.

“Methane released from thawing permafrost creates a positive feedback loop, where increased global warming leads to more permafrost thaw and even greater warming.”

According to Dr Tyson, methane-metabolising organisms typically occur within a single cluster of microorganisms called Euryarchaeota. But when his team performed metagenomic sequencing of an aquifer in the Surat Basin, near Roma in Queensland, they recovered two near-complete genomes belonging to the archaeal phylum Bathyarchaeota.

Bathyarchaeota are an evolutionarily diverse group of microorganisms found in a wide range of environments, including deep-ocean and freshwater sediments. The organisms were discovered using techniques that sequence DNA on a large scale and assemble these sequences into genomes using advanced computational tools.

“To use an analogy, the finding is like knowing about black and brown bears, and then coming across a giant panda,” Dr Tyson said.

“They have some basic characteristics in common, but in other ways they are fundamentally different.”

Dr Tyson concluded that his team’s study “expands our knowledge of diversity of life on Earth and suggests we are missing other organisms involved in carbon cycling and methane production” — an area which is “crucial in helping us understand future climate change scenarios”.

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