THERMOHYDROGENIUM-KIRISHIENSE GEN-NOV AND SP-NOV, A NEW ANAEROBIC THERMOPHILIC BACTERIUM

Six strains of a new anaerobic thermophilic non-sporeforming bacterium were isolated in pure culture from industrial yeast biomass. Cells we re rod-shaped (0.4-0.8 x 1.0-11.0 mum), non-motile. They stained gram- negative, but outer membrane was not present. The growth occurred betw een 45-75-degrees-C, the optimal temperature is 65-degrees. Optimal pH value was 7.0-7.4. The bacterium utilized for growth several sugars, starch and yeast extract. The best source of nitrogen was peptone. The main fermentation products of glucose were ethanol, acetate, H-2 and CO2. As minor products isopropanol, butanol, butyrate and lactate were found. Glucose was metabolized via the Embden-Meyerhoff pathway. Cyto chromes and quinones were not found. DNA-base composition was 33.2-34. 0 mol%. The DNA-DNA hybridization and 5S rRNA nucleotide sequences sho wed distantly related of isolated stains to phenotypical similar bacte ria. It was proposed to consider the isolated bacterium as Thermohydro genium kirishiense gen. nov. and sp. nov.