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Hydrogen is a key energy-yielding substrate for microbial processes in the deep biosphere. Fracture water of a deep gold mine in South Africa is a well-known example of the ecosystem based on a hydrogenotrophic sulfate reducer, “Candidatus Desulforudis audaxviator.” The present work reports the cultivation and pure culture isolation of a novel obligate chemolithotroph reducing sulfate during growth on hydrogen or formate. Phylogenetic analysis of the 16S rRNA gene of the strain Tu-874 showed its clusterization with its closest cultured relative, “Candidatus Desulforudis audaxviator.” However, the low 16S rRNA sequence similarity of 88.95% indicates that the organism represents a new taxonomic group above the species level.

Sulfate-reducing bacteria (SRB) of the genus Desulfovibrio are one of the groups occurring in elevated numbers in the gut of children with autistic spectrum disorders (ASD). Until now, high abundance of Desulfovibrio in individuals with RAS has been shown only by molecular methods. No cultured forms have been isolated from the gastrointestinal tract of autists. A conceivable mechanisms of SRB effect is conversion of iron into biologically unavailable forms of sulfides, causing its deficiency in the organism. In this study we isolated two Desulfovibrio strains from feces of the children with diagnosed ASD. In experiments Desulfovibrio desulfuricans AY5 formed crystalline iron sulfides, greigite and pyrite, containing iron in a biologically unavailable form.

Micromycetes can precipitate metals in the form of insoluble oxalates, thus participating in metal removal from geochemical cycling and in secondary mineral formation. Metal precipitation has a practical application for bioleaching and bioremediation. Micromycetes from the genus Aspergillus are used as model organisms to study metal precipitation. All known biomineralization processes carried out by micromycetes described so far involved mesophilic organisms. Thermophilic eukaryotes may be advantageous for biotechnologies. This study reports the isolation of thermophilic/thermotolerant Aspergillus spp. from burning wastes of coal mining in Kuzbass and their participation in formation of insoluble copper oxalate, moolooite. Copper-enriched extracellular vesicles formed in the process may act as nucleation sites for the moolooite crystals formation.