show Abstracthide AbstractWe isolated a novel Sulfolobus species, denoted strain Sulfolobus sp. A20, from an acidic hot spring in Laguna Fumarólica, Costa Rico, and sequenced the genome of the strain. The 16S rRNA gene of strain A20 exhibits the highest sequence similarity (~95.6%) to those of S. islandicus and S. solfataricus isolates, suggesting the strain represents a novel Sulfolobus species. The genome of strain A20 was compared with all other available Sulfolobus genomes, and analyses of the pathways of carbon, nitrogen and sulfur metabolism in various Sulfolobus strains were performed.