Scientists collect bacteria samples from the Rotokawa Geothermal Field, near Taupo. Photo / Supplied
Gas-guzzling bugs that live comfortably in some of New Zealand's most extreme environments could help combat climate change.
Extremophile bacteria can live in temperatures of 121C in hydrothermal vents - we humans can't stand anything hotter than 40C.
Here in New Zealand, they're quite at home amid the extreme acidity and alkalinity levels of hot springs around the Taupo Volcanic Zone.
To scientists, they're intriguing for a range of interesting reasons - one of them being that they might possess anti-microbial agents able to be used as thermo-stable antibiotics.
Now, a new study has shown how one form of bacteria might help better tackle greenhouse gas emissions.
The research, led by an international team of scientists, found how methane-oxidising bacteria - key organisms responsible for greenhouse gas mitigation - are more flexible and resilient than previously thought.
Soil bacteria that oxidise methane, called methanotrophs, are globally important in capturing methane before it enters the atmosphere, and scientists now know that they can consume hydrogen gas to enhance their growth and survival.
The team's study, supported by the Marsden Fund and recently published in the International Society for Microbial Ecology Journal, has big implications for combating greenhouse gas emissions.
Industrial companies are already using methanotrophs to convert methane gas emissions into useful products like liquid fuels and protein feeds.
The scientists were able to isolate and characterise a methanotroph from the Rotokawa Geothermal Field, near Taupo, and found how the strain could grow on methane or hydrogen separately, but performed best when both gases were available.
That discovery was important because it showed how key consumers of methane emissions were also able to grow on inorganic compounds such as hydrogen - something scientists previously hadn't understood.
"One of the major underlying beliefs about these bacteria was that they were very specifically only using methane gas, and what we showed was that they also use hydrogen, and this actually benefits them," said the study's lead author, Dr Carlo Carere, of GNS Science.
"So in an environment that is potentially going to experience limitations in methane or oxygen, they prefer to use hydrogen and methane together."
Industrial processes such as petroleum production and waste treatment release large amounts of the methane, carbon dioxide and hydrogen into the atmosphere.
"By using these gas-guzzling bacteria, it's possible to convert these gases into useful liquid fuels and feeds instead," said study co-author Dr Chris Greening, of the Centre for Geometric Biology at Australia's Monash University.
The findings could also explain why methanotrophs were abundant in soil ecosystems, said Greening, who joined Carere and collaborators from the University of Otago, Scion, University of Manitoba, Montana State University and CSIRO.
Methane was a challenging energy source to assimilate, and by being able to use hydrogen as well, methanotrophs could grow better in a range of conditions.
"It was their very existence in such environments that led us to investigate the possibilities that these organisms might also use other energy-yielding strategies," Greening said.
Carere, a Canadian, said he had been surprised by the diversity and abundance of extremophile bacteria that thrived in New Zealand's geothermal environments.
"I'm biased as a microbiologist, but I think it should be in everyone's interest to know a little bit more about them," Carere said.
"New Zealand has some amazing geothermal areas and because of that there are some amazing microbial populations.
"And because of genomic technology, we can now really characterise these communities and make pretty informed guesses about what they're doing, and the role they are playing in the ecosystem."