title: Isolation and characterization of Thermococcus sibiricus sp. nov. from a Western Siberia high-temperature oil reservoir.
abstract: Anaerobic organotrophic hyperthermophilic Archaea were isolated from five of eight samples from oil wells of the Samotlor oil reservoir (depth, 1,799-2,287 m; temperature, 60 degrees-84 degrees C). Three strains were isolated in pure cultures and characterized phylogenetically on the basis of comparison of the 16S rRNA gene sequences. All strains belonged to a new species of the genus Thermococcus, with Thermococcus litoralis, Thermococcus aggregans, Thermococcus fumicolans, and Thermococcus alcaliphilus being the nearest relatives (range of sequence similarity, 97.2%-98.8%). Strain MM 739 was studied in detail. The new isolate grew on peptides but not on carbohydrates. Elemental sulfur had a stimulatory effect on growth. The temperature range for growth was between 40 degrees and 88 degrees C, with the optimum at 78 degrees C; the pH range was 5.8 to 9.0, with the optimum around 7.3; and the salinity range was 0.5% to 7.0%, with the optimum at 1.8%-2.0%. The doubling time at optimal growth conditions was about 43 min. The G+C content of the DNA was 38.4 mol%. The DNA-DNA relatedness between strain MM 739 and T. litoralis was 27%; between strain MM 739 and T. aggregans, it was 22%. Based on the phenotypic and genomic differences with known Thermococcus species, the new species Thermococcus sibiricus is proposed. The isolation of a hyperthermophilic archaeum from a deep subsurface environment, significantly remote from shallow or abyssal marine hot vents, indicates the existence of a subterranean biosphere inhabited by indigenous hyperthermophilic biota.
authors.affiliation: Institute of Microbiology, Russian Academy of Sciences, Moscow.
authors.forename: M L
authors.initials: ML
authors.lastname: Miroshnichenko
authors.forename: H
authors.initials: H
authors.lastname: Hippe
authors.forename: E
authors.initials: E
authors.lastname: Stackebrandt
authors.forename: N A
authors.initials: NA
authors.lastname: Kostrikina
authors.forename: N A
authors.initials: NA
authors.lastname: Chernyh
authors.forename: C
authors.initials: C
authors.lastname: Jeanthon
authors.forename: T N
authors.initials: TN
authors.lastname: Nazina
authors.forename: S S
authors.initials: SS
authors.lastname: Belyaev
authors.forename: E A
authors.initials: EA
authors.lastname: Bonch-Osmolovskaya
mesh_terms: D019641:DNA, Archaeal / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D006358:Hot Temperature; D009693:Nucleic Acid Hybridization; D010578:Petroleum; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012800:Siberia; D019712:Thermococcus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D019641:DNA, Archaeal; D004275:DNA, Ribosomal; D010578:Petroleum; D012336:RNA, Ribosomal, 16S