ALBERT

Description: A novel hyperthermophilic organo-heterotrophic archaeon, strain OGL-20P(sup T), was isolated from 'black smoker' chimney material from the Rainbow hydrothermal vent site on the Mid-Atlantic Ridge (36.2 N; 33.9 W). The cells of strain OGL-20P(sup T) have an irregular coccoid shape and are motile with a single flagellum. Growth was observed to occur within the pH range 5.0-8.5 (optimum pH 7.0), NaCl concentration range 1-5 % (w/v) (optimum 3 %), and temperature range 55-94 C (optimum 83-85 C). Novel isolate is strictly anaerobic and obligately dependent from elemental sulfur as electron acceptor, but it cannot reduce sulfate, sulfite, thiosulfate, iron (III) or nitrate. Proteolysis products that can be utilized as substrates during sulfur-reduction are: peptone, bactotryptone, casamino-acids, and yeast extract. Strain OGL-20P(sup T) is resistant to ampicillin, chloramphenicol, kanamycin, and gentamycin, but sensitive to tetracycline and rifampicin. The G+C content of DNA is 57.1 mol% . Comparative 16S rRNA gene sequence analysis revealed that strain OGL-20P(sup T) is most closely related to Thermococcus celer and 'T. barossii', but no significant homology by DNA-DNA hybridization was observed between those species and the new isolate. On the basis of physiological and molecular properties of the new isolate, the name Thermococcus thioreducens sp. nov., is proposed. The type strain is OGL-20P(sup T) (= ATCC BAA-394(sup T) = DSM 1498(sup T)).