Bacteria that "eat" only air found in cold deserts around the world
A few years ago researchers at the University of New South Wales (UNSW) discovered bacteria in Antarctica that could survive on nothing but air. Now the team has found that this handy ability might not be limited to the South Pole, with evidence turning up in other cold desert locations. The finding could have implications for life beyond Earth, too.
Every living thing needs to get energy from somewhere. For animals that’s food, whether plants or meat or both. For plants, energy comes from sunlight. And for bacteria, it can be a mix of these things, or through “fixing” inorganic compounds in soil.
In 2017, the UNSW researchers discovered bacteria in Antarctica that gained their energy from a new source – the air itself. In low-nutrient soil, these bugs instead pull hydrogen, carbon dioxide and carbon monoxide out of the air around them, allowing them to thrive in environments where there’s very little other life. This phenomenon is known as atmospheric chemosynthesis.
And now in a follow-up study, the team has found that this ability may not be limited to Antarctica. The researchers found that the two genes previously linked to atmospheric chemosynthesis are abundant in soil in two other similar environments – the Arctic and the Tibetan Plateau.
The researchers collected 122 soil samples from 14 sites in these three regions, then extracted and sequenced DNA from them. They found that the two genes of interest were present in all 122 samples, in different amounts depending on the level of nutrients each location had to offer.
“By looking at the environmental parameters in the soil, that's how we knew there was low carbon, low moisture and other factors at play,” says Angelique Ray, lead author of the study. “So, we correlated the target genes for the carbon fixation process against the different sites and found the locations which are drier and lower in nutrients – carbon and nitrogen – had a greater potential to support this process, which made sense.”
The team says that this study has wider implications beyond just bacteria. It could affect our understanding of the planet’s carbon budget by revealing a previously-unknown carbon sink. It might even suggest that alien life could survive in harsher environments than we thought possible.
And we may know sooner rather than later. NASA’s latest Mars mission, with the Perseverance rover, is currently en-route to the Red Planet, where it will analyze the soil for signs of ancient microbial life.
In the meantime, the researchers on the new study plan to try to identify the bacteria that can live on atmospheric chemosynthesis.
“As part of the next phase, we aim to isolate one of these novel bacteria in the laboratory – to obtain a pure culture,” says Belinda Ferrari, lead author of the study. “This is difficult because the bacteria are used to growing on very little and an agar plate is different to their natural environment. Hopefully then, we can fully understand the conditions these bacteria need to carry out this unique process of living on air.”
The research was published in the journal Frontiers.