Microbes living on air a global phenomenon

Date:
August 19, 2020
Source:
University of New South Wales
Summary:
Researchers have found their previous discovery of bacteria living
on air in Antarctica is likely a process that occurs globally,
further supporting the potential existence of microbial life on
alien planets.



FULL STORY ==========================================================================
In their first follow-up to a high-profile 2017 study which showed
microbes in Antarctica have a unique ability to essentially live on air, researchers from UNSW Sydney have now discovered this process occurs in
soils across the world's three poles.


========================================================================== Specifically, researchers found the target genes responsible for the atmospheric chemosynthesis phenomenon they discovered are abundant
and widely distributed in the polar soils of the Antarctic, Arctic and
Tibetan Plateau in the Hindu Kush-Himalayas.

The new research was published in the journal Frontiers this month and
was a collaboration between UNSW, the Australian Antarctic Division and
China's Institute of Tibetan Plateau Research.

The study's senior author Associate Professor Belinda Ferrari, of UNSW
Science, said living on air was such a minimalistic way to survive that
their findings lent further potential for microbial life to exist on
other planets.

"This is what NASA's Mars 2020 Perseverance Rover is aiming to do --
to search for signs of ancient microbial life in core samples of Martian
rock and soil," A/Prof Ferrari said.

"A future mission will take the samples back to Earth and NASA scientists
will analyse the soil in a similar way we do, to try and see whether
there are any indicators of life." A/Prof Ferrari said the researchers' findings meant that microbes which use trace gases as their energy
and carbon source to grow -- unlike photosynthesis which uses light --
was not a process isolated to Antarctica.



========================================================================== "There are whole ecosystems probably relying on this novel microbial
carbon fixation process where microbes use the energy obtained from
breathing in atmospheric hydrogen gas to turn carbon dioxide from the atmosphere into carbon -- in order to grow," she said.

"We think this process occurs simultaneously alongside photosynthesis when conditions change, such as during the polar winter when there is no light,
but we aim to confirm this hypothesis in the next stage of our research.

"So, while more work is needed to confirm this activity occurs globally,
the fact that we detected the target genes in the soils of the three
poles means this novel process likely occurs in cold deserts around the
world, but has simply been overlooked until now." Antarctic, Artic and
Tibetan Plateau soil analysed Researchers analysed 122 soil samples from
14 terrestrial cold desert sites across Antarctica (Windmill Islands
and Vestfold Hills), the high Arctic and Tibetan Plateau, which they
collected between 2005 and 2019.



==========================================================================
The study's lead author, UNSW PhD candidate Angelique Ray, said one of
the big questions the team had when they finished their previous study
was whether this new process of atmospheric chemosynthesis -- also known
as carbon fixation or carbon sink -- was similarly occurring in other
places around the world.

"So, this time we did a global study. We collected the top 10-centimetre
layer of soil from various sites at the three poles, which is the depth
where most of the organisms we study are found," she said.

"The ground at those locations is completely frozen for most of
the year -- and there's not a lot of soil because it's mostly rock."
The researchers extracted DNA from the soil samples and then sequenced
the DNA to detect the target genes responsible for the process of carbon fixation.

Ms Ray said the scientists also conducted environmental analyses of each location to gauge the conditions under which the microbes lived.

"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,"
she said.

"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." Findings to change thinking
on carbon fixation A/Prof Ferrari said the researchers' findings would
change the way scientists thought about the limitations required for
life to exist, as well as how microbiology was taught.

"By investigating places outside Antarctica, we can determine how
significant the contribution of this new form of chemotrophy is to the
global carbon budget," she said.

"Before we discovered this new carbon sink process, the two main known chemotrophic forms were photosynthesis and geothermal chemotrophy --
the latter is where bacteria harness inorganic compounds like hydrogen
sulfide to fix carbon.

"But now we have found the genes involved in this process are abundant
in cold deserts, although we are yet to study hot deserts, our finding
probably indicates atmospheric chemosynthesis is contributing to
the global carbon budget." A/Prof Ferrari said it was likely the
bacteria which survived on nothing but air had become key players in
the environments in which they lived.

"A lot of these ecosystems are quite dry and nutrient poor -- so, these locations are mostly dominated by bacteria," she said.

"Particularly at the original east Antarctic sites we studied, there is
not much else there apart from some mosses and lichens (fungus).

"Because these bacteria have adapted to survive and have the ability to
use trace gases to live, their environment has selected them to become significant contributors to their ecosystems." A/Prof Ferrari said the researchers looked forward to making new discoveries in carbon fixation.

"As part of the next phase, we aim to isolate one of these novel bacteria
in the laboratory -- to obtain a pure culture," she said.

"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."

========================================================================== Story Source: Materials provided by University_of_New_South_Wales. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Angelique E. Ray, Eden Zhang, Aleks Terauds, Mukan Ji, Weidong Kong,
Belinda C. Ferrari. Soil Microbiomes With the Genetic Capacity for
Atmospheric Chemosynthesis Are Widespread Across the Poles and Are
Associated With Moisture, Carbon, and Nitrogen Limitation. Frontiers
in Microbiology, 2020; 11 DOI: 10.3389/fmicb.2020.01936 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200819094756.htm

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