Varunaivibriosulfuroxidanstype strain TC8Tis a mesophilic, facultatively anaerobic, facultatively chemolithoautotrophic alphaproteobacterium isolated from a sulfidic shallow-water marine gas vent located at Tor Caldara, Tyrrhenian Sea, Italy.V. sulfuroxidansbelongs to the familyThalassospiraceaewithin the Alphaproteobacteria, withMagnetovibrio blakemoreias its closest relative. The genome ofV. sulfuroxidansencodes the genes involved in sulfur, thiosulfate and sulfide oxidation, as well as nitrate and oxygen respiration. The genome encodes the genes involved in carbon fixation via the Calvin–Benson–Bassham cycle, in addition to genes involved in glycolysis and the TCA cycle, indicating a mixotrophic lifestyle. Genes involved in the detoxification of mercury and arsenate are also present. The genome also encodes a complete flagellar complex, one intact prophage and one CRISPR, as well as a putative DNA uptake mechanism mediated by the type IVc (aka Tad pilus) secretion system. Overall, the genome ofVarunaivibrio sulfuroxidanshighlights the organism’s metabolic versatility, a characteristic that makes this strain well-adapted to the dynamic environmental conditions of sulfidic gas vents.