Asgard archaea modulate potential methanogenesis substrates in wetland soil

Area of Science:

• Microbial Ecology
• Archaea
• Biogeochemical Cycles

Background:

• Asgard archaea roles in eukaryogenesis and marine cycles are known.
• Their function in terrestrial soil ecosystems, especially wetland soils, is largely uncharacterized.
• Understanding their contribution to methane cycling in soils is of significant interest.

Purpose of the Study:

• To investigate the metabolic potential and ecological roles of soil-associated Asgard archaea.
• To reconstruct genomes of soil-dwelling Asgard archaea and predict their in situ functions.

Main Methods:

• Genome reconstruction of two soil-associated Atabeyarchaeia and one Freyarchaeia.
• Metatranscriptomic analysis to identify expressed genes and metabolic pathways.

Main Results:

• Complete genomes for Atabeyarchaeia and Freyarchaeia were reconstructed.
• Expressed genes indicated pathways for [NiFe]-hydrogenases, pyruvate oxidation, and carbon fixation (Wood-Ljungdahl pathway).
• Other expressed genes involved amino acid metabolism, anaerobic aldehyde oxidation, peroxide detoxification, and carbohydrate breakdown to acetate and formate.

Conclusions:

• Soil-associated Asgard archaea, specifically Atabeyarchaeia and Freyarchaeia, are predicted to be non-methanogenic acetogens.
• These archaea have a potential role in carbon cycling within terrestrial environments.
• This study expands the known ecological roles of Asgard archaea beyond marine environments.