Oral Presentation Australian Microbial Ecology Conference 2024

Resilient Antarctic soil bacteria sustain trace gas oxidation across wide temperature ranges (#81)

Tess Hutchinson 1 , Pok Man Leung 1 , Francesco Ricci 1 , Thanavit Jirapanjawat 1 , Chris Greening 1
  1. Monash University, Melbourne

Polar desert soils host diverse and abundant microbial communities despite limited nutrients and frequent temperature and light fluctuations. Adapting to oligotrophic conditions, most bacteria possess high-affinity hydrogenases and carbon monoxide dehydrogenases, allowing them to survive on atmospheric trace gases such as hydrogen (H2) and carbon monoxide (CO) for energy generation and chemosynthesis. Despite the foundational importance in sustaining microbial diversity in a slowly warming climate, little is known about the thermal flexibility of trace gas oxidation processes. Here we investigate oxidation of H2, CO and methane (CH4) in Antarctic soils under 12 different temperatures, ranging from -20 °C to 70 °C. H2 oxidation occurs at fast rates from -20 °C to, unexpectedly, 70 °C, inferring the remarkable resilience of hydrogenotrophic microbes in these communities. Optimal temperatures for H2 and CO oxidation are between 17 - 30 °C, despite the community’s polar origin. In contrast, CH4 oxidation is much slower and occurs under a narrower temperature range, operating optimally between 4 -25 °C. As polar regions cover approximately 5 x 106 km2 of the Earth, this work importantly enables prediction on the impact of future climate change on these soil communities. Results suggest a warming climate may promote activities of Antarctic soil communities but it remains to be evaluated whether this pattern will hold true.