Hot life in Antarctica: a novel metabolically versatile <i>Pyrodictiaceae</i> 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 <i>Pyrodictiaceae</i>. 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 <i>Pyrodictiaceae</i>-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 <i>Pyrodictiaceae</i>, highlighting Antarctic marine volcanoes as unique refuges for hyperthermophiles and as valuable models for investigating life's habitability under extreme temperatures.