New preprint describing novel lineages of Asgard archaea from complete genomes.

Asgard archaea modulate potential methanogenesis substrates in wetland soil

Luis E. Valentin-Alvarado, Kathryn E. Appler, Valerie De Anda, Marie C. Schoelmerich, Jacob West-Roberts, Veronika Kivenson, Alexander Crits-Christoph, Lynn Ly, Rohan Sachdeva, David F. Savage, Brett J. Baker, Jillian F. Banfield

The roles of Asgard archaea in eukaryogenesis and marine biogeochemical cycles are well studied, yet their contributions in soil ecosystems are unknown. Of particular interest are Asgard archaeal contributions to methane cycling in wetland soils. To investigate this, we reconstructed two complete genomes for soil-associated Atabeyarchaeia, a new Asgard lineage, and the first complete genome of Freyarchaeia, and defined their metabolism in situ. Metatranscriptomics highlights high expression of [NiFe]-hydrogenases, pyruvate oxidation and carbon fixation via the Wood-Ljungdahl pathway genes. Also highly expressed are genes encoding enzymes for amino acid metabolism, anaerobic aldehyde oxidation, hydrogen peroxide detoxification and glycerol and carbohydrate breakdown to acetate and formate. Overall, soil-associated Asgard archaea are predicted to be non-methanogenic acetogens, likely impacting reservoirs of substrates for methane production in terrestrial ecosystems.

One-Sentence Summary Complete genomes of Asgard archaea, coupled with metatranscriptomic data, indicate roles in production and consumption of carbon compounds that are known to serve as substrates for methane production in wetlands.

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