Hot life in Antarctica: a novel metabolically versatile Pyrodictiaceae genus thriving at a volcanic-cryosphere-marine interface.

Deception Island fumaroles in Antarctica represent rare environments where extreme heat intersects with cryospheric and marine conditions, creating remarkable environmental gradients. From the near-boiling sediments, we reconstructed a high-quality metagenome-assembled genome affiliated with the Pyrodictiaceae. Phylogenomic analyses revealed that this genome, proposed to represent Ca. Pyroantarcticum pellizari, forms a distinct lineage separated from known genera in the family. Functional annotation uncovered a versatile metabolic repertoire, including pathways for sulfur and nitrogen cycling, peptide and amino acid transport, and mixotrophic energy conservation. Stress-response systems such as reverse gyrase, thermosome, and small heat-shock proteins were complemented by lineage-specific genes related to membrane stability, metal detoxification, and Pyrodictiaceae-specific cannulae. These adaptations likely support survival under sharp temperature gradients, hydrogen sulfide emissions, and high metal concentrations at the volcanic-cryosphere-marine interface. Our findings expand the phylogenetic and ecological scope of Pyrodictiaceae, highlighting Antarctic marine volcanoes as unique refuges for hyperthermophiles and as valuable models for investigating life's habitability under extreme temperatures.