Living on thin air – researchers discover microbes that could survive beyond earth
Monash microbiologists have shown how life can exist in extreme environments.
They discovered bacteria in the Antarctic continent that can endure even when conventional food sources and water are absent – by scavenging the trace gases present in the atmosphere as alternative fuel sources.
The findings have far-reaching implications for the search for extra-terrestrial life. The study, led by the UNSW Sydney, suggests that microbes could survive on trace gases if introduced into the atmospheres of other planets.
“It was thought for many years that the extremely cold, dry soils of Antarctica were sterile, but modern DNA-based techniques have shown they harbour diverse microbial lifeforms,” said study co-first author Dr Chris Greening from the Monash Centre for Geometric Biology.
“We found that hundreds of bacterial species and millions of cells were present in every gram of soil we looked at,” he said.
“The big question is how these microbes survive when there is too little water to sustain photosynthesis, the process that most ecosystems depend on.
“We discovered that they literally live on thin air – consuming the tiny amounts of hydrogen and carbon monoxide in the air to make usable energy and biomass.”
The Australasian-based study, involving UNSW, the School of Biological Sciences at Monash University, the Australian Centre for Ecogenomics at the University of Queensland, GNS Science in New Zealand, and the Australian Antarctic Division, is published in the journal Nature.
The researchers sampled microbial DNA from the surface soils of two desert sites in Eastern Antarctica. Using this DNA, they used cutting-edge methods to reconstruct the genomes of 23 of the microbes that lived there, including those from two groups of previously uncharacterized bacteria called WPS-2 and AD3.
They found the dominant organisms in the soils were highly specialized bacteria that harboured genes that allowed them to consume hydrogen, carbon monoxide, and carbon dioxide from the atmosphere as energy and carbon sources. They demonstrated that these organisms consumed gases from the air at fast enough rates to survive in this hostile environment.
“This new understanding about how life can still exist in physically extreme and nutrient-starved environments like Antarctica opens up the possibility of atmospheric gases supporting life on other planets,” said study senior author Associate Professor Belinda Ferrari from UNSW Sydney.
“These bacteria might survive in Mars if they were introduced there,” said Dr Greening.
“After all, the ingredients needed for these organisms to survive are all found in the Martian atmosphere – hydrogen, carbon monoxide, carbon dioxide, and oxygen – and the temperatures in Mars’ equator are comparable to those of Antarctica.”
The study provides new insight into the nutritional limits of life. Whereas most characterised ecosystems use energy from the sun or the earth to grow, atmospheric energy sources seem to primarily support these desert soils.
The scientists say more research is now needed to see if this use of atmospheric gases as an alternative energy source is more widespread in Antarctica and elsewhere.
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Captions: Adams Flat (credit: Tom Mooney) and Robinson Ridge (credit: UNSW), the two sites in Antarctica where microbes were collected.