Abstract <p>This study presents the results of a physiological and genomic analysis of the archaeal strain <i>Acidiplasma</i> sp. YE-1, a representative of extremely acidophilic, moderately thermophilic archaea of the family <i>Ferroplasmaceae</i>. This strain was dominant in a microbial community performing biooxidation of a pyrite–arsenopyrite gold-bearing concentrate. The strain is a moderately thermophilic extreme acidophile capable of oxidizing ferrous iron and sulfur, requiring an organic substrate in the medium for growth—characteristics typical of the genus <i>Acidiplasma</i>. Investigation of pyrite oxidation by <i>Acidiplasma</i> sp. YE-1 demonstrated that the strain oxidized pyrite in pure culture at a low rate, despite its ability to oxidize Fe²⁺ ions and sulfur. During pyrite bioleaching by a mixed culture of <i>Acidiplasma</i> sp. YE-1 and <i>Acidithiobacillus caldus</i> MBC-1, pyrite oxidation proceeded several times faster than in the respective pure cultures, which may indicate metabolic and physicochemical interactions between these microorganisms and the mineral. The mechanisms underlying these interactions require further study. A complete circular genome of <i>Acidiplasma</i> sp. YE-1 (GenBank accession number CP133599), 1 718 531 bp in length, was reconstructed—currently the only complete genome available for members of this genus. The genome contains a gene encoding sulfocyanin, a key electron transport chain protein involved in iron oxidation, as well as genes of sulfur-oxidizing enzymes, including sulfur oxygenase–reductase (SOR) and components of the cytoplasmic DsrE complex. Genes associated with the transport and catabolism of organic compounds and with the 3-hydroxypropionate/4-hydroxybutyrate carbon fixation cycle were also identified. The results provide a more detailed characterization of the genetic potential of this microorganism and allow comparative genomic analysis with previously described strains <i>Acidiplasma aeolicum</i> and <i>Acidiplasma cupricumulans</i>.</p>