Thermovenabulum ferriorganovorum gen. nov., sp. nov., a novel thermophilic, anaerobic, endospore-forming bacterium.

A thermophilic, anaerobic, spore-forming bacterium (strain Z-9801T) was isolated from a terrestrial hydrothermal source in the Uzon caldera on the Kamchatka peninsula. Cells of strain Z-9801T were straight, sometimes branched rods, 0.5-0.6 microm in diameter and 1.5-7.0 microm in length, with peritrichous flagella. The temperature range for growth was 45-76 degrees C, with an optimum at 63-65 degrees C. The pH range for growth was 4.8-8.2, with an optimum at 6.7-6.9. The substrates utilized by strain Z-9801T included peptone, yeast extract, beef extract, Casamino acids, starch, pyruvate, melibiose, sucrose, fructose, maltose, xylose and ribose. The fermentation products from melibiose were ethanol, acetate, H2 and CO2. Strain Z-9801T used H2 in the presence of Fe(III) and an organic electron donor. Strain Z-9801T reduced Fe(III), Mn(IV), nitrate, fumarate, sulfite, thiosulfate, elemental sulfur and 9,10-anthraquinone 2,6-disulfonate. The G+C content of strain Z-9801T DNA was 36 mol%. 16S rDNA sequence analysis revealed that the isolated organism forms a separate branch within the Bacillus/Clostridium group. On the basis of physiological properties and phylogenetic analysis, it is proposed that strain Z-9801T (= DSM 14006T = UNIQEM 210T) should be assigned to a novel species of a new genus, Thermovenabulum ferriorganovorum gen. nov., sp. nov.