Genomic and experimental evidence from Antarctic geothermal sites indicates diverse thermophiles are globally cosmopolitan

Mt. Erebus, the world’s southernmost active volcano, is highly isolated, yet a previous study found its heated soils contain prokaryotes found elsewhere globally. This was unexpected, as non-sporulating thermophilic microorganisms are thought to be dispersal limited. We searched for the presence of metagenome assembled genomes (MAGs) from Antarctic geothermal sites outside Antarctica, finding that 62% of MAGs had matching species globally. Three of these cosmopolitan thermophiles isolated from Mt. Erebus could survive atmospheric-like conditions, with UV being the strongest selective pressure. Moreover, hot soils from Hawaiʻi sampled four years after a lava flow hosted many thermophilic MAGs with identical strains elsewhere globally, indicating that dispersal/recolonisation by thermophiles can be rapid. Finally, ice core sections from Fang Glacier (Mt. Erebus) associated with volcanic events were enriched in thermophiles, implying that thermophiles could disperse via volcanic events. Our findings dispel the common conception of thermophilic microorganisms as being inherently dispersal limited.