Antarctic Microbes Generate Energy from Atmospheric Gases, Thriving in Extreme Cold
Antarctica experiences long, dark winters with temperatures consistently below freezing, making sunlight-dependent life challenging. From April until August, sunlight is absent in many regions, hindering photosynthetic life like plants and algae to produce energy.
A new study published in The ISME Journal reveals that Antarctic microbes can generate energy from atmospheric gases at temperatures as low as –20°C.
This groundbreaking research sheds light on life's incredible survival mechanisms in Antarctica's extreme temperatures and explores the potential impacts of climate change on these vital processes.
Energy from Air: Aerotrophy
In 2017, previous research first identified that many Antarctic microbes produce energy from atmospheric gases at low concentrations. This unique process is known as 'aerotrophy.'
These microbes employ specific enzymes to metabolize hydrogen and carbon monoxide directly from the atmosphere.
This provides a crucial energy source in Antarctica's nutrient-deficient desert soils, especially where sunlight is scarce.
The exact temperature limits of aerotrophy were previously unknown, prompting researchers to investigate its year-round viability.
Laboratory and Field Findings
To understand aerotrophy's full scope, researchers collected surface soil samples from East Antarctica between 2022 and 2024. These samples underwent laboratory analysis.
Scientists measured the rate at which microbes consumed atmospheric gases and sequenced microbial DNA. This allowed them to identify specific species, genes, and their potential energy sources.
Laboratory experiments successfully demonstrated aerotrophy at both typical summer (4°C) and extreme winter (–20°C) temperatures.
This confirms that hydrogen and carbon monoxide serve as vital, year-round food sources for these Antarctic microbes.
Remarkably, some microbes showed the ability to generate energy from hydrogen at temperatures reaching up to 75°C, indicating their adaptation to cold but not a restriction to it. Further in-situ experiments conducted directly in Antarctica validated that soil microbes actively utilize hydrogen under real-world environmental conditions.
Primary Producers in Antarctic Soils
DNA sequencing provided critical insights, revealing that the majority of microbes found in Antarctic soils possess genes essential for hydrogen-based energy generation. Many of these microbes also carry genes enabling them to assimilate carbon directly from the atmosphere.
These atmospheric-gas-consuming microbes, or 'aerotrophs,' function as 'primary producers,' forming new biomass from atmospheric gases.
This is a significant distinction from most terrestrial ecosystems, where photosynthesis typically forms the base of the food chain. In Antarctic desert soils, photosynthesis is infrequent due to harsh conditions.
Researchers hypothesize that aerotrophy takes on the crucial primary producer role in many Antarctic regions. This offers a distinct advantage: it operates year-round and does not require liquid water, unlike photosynthesis.
Climate Change Implications
The study extended its analysis to investigate the potential effects of global warming on aerotrophy.
Projections suggest a 4% increase in atmospheric hydrogen utilization by aerotrophs under low-emissions scenarios. Under very high-emissions scenarios, this increase could be substantial, reaching up to 35%, with similar trends observed for carbon monoxide.
Hydrogen plays a critical role in influencing the atmospheric persistence of greenhouse gases, such as methane.
Globally, soils, including their diverse microbial communities, consume an impressive 82% of atmospheric hydrogen, functioning as a significant hydrogen sink within the global hydrogen cycle.
This research enhances our understanding of the resilience of Antarctica’s unique microbial ecosystems in the face of climate change, recognizing temperature as one of several factors at play.