Thermococcus gammatolerans sp. nov., a hyperthermophilic archaeon from a deep-sea hydrothermal vent that resists ionizing radiation

Abstract

Enrichments for anaerobic organotrophic hyperthermophiles were performed with hydrothermal chimney samples collected at the Guaymas Basin (27˚019 N, 111˚249 W). Positive enrichments were submitted to c-irradiation at a dose of 30 kGy. One of the resistant strains, designated strain EJ3 T , formed regular motile cocci. The new strain grew between 55 and 95˚C, with an optimum growth temperature of 88˚C. The optimal pH for growth was 6?0, and the optimum NaCl concentration for growth was around 20 g l 21 . Strain EJ3 T was an obligately anaerobic heterotroph that utilized yeast extract, tryptone and peptone. Elemental sulfur or cystine was required for growth and reduced to hydrogen sulfide. The G+C content of the genomic DNA was 51?3 mol%. As determined by 16S rRNA gene sequence analysis, the organism was most closely related to Thermococcus celer, Thermococcus guaymasensis, Thermococcus hydrothermalis, Thermococcus profundus and Thermococcus gorgonarius. However, no significant homology was observed between them by DNA-DNA hybridization. The novel organism also possessed phenotypic traits that differ from those of its closest phylogenetic relatives. Therefore, it is proposed that this isolate, which constitutes the most radioresistant hyperthermophilic archaeon known to date, should be described as the type strain of a novel species, Thermococcus gammatolerans sp. nov. The type strain is EJ3 T (=DSM 15229 T =JCM 11827 T ).

Microbial methane production in deep aquifer associated with the accretionary prism in Southwest Japan

“…SMD-A03 showed the closest match to the 16S rRNA gene from the cultured organism Methanothermobacter thermautotrophicus (99.4% identity), a thermophilic methanogen that uses H 2 and CO 2 for methanogenesis (Zeikus and Wolfe, 1972). The remaining OTU, SMD-A04, was closely related to the 16S rRNA gene from the cultured organism Thermococcus gammatolerans (82.3% identity), which is known as a thermophilic heterotrophic archaeon isolated from a deep-sea hydrothermal vent (Jolivet et al, 2003).…”

Contribution of crenarchaeal autotrophic ammonia oxidizers to the dark primary production in Tyrrhenian deep waters (Central Mediterranean Sea)

“…Similarly to other members of Eury-and Crenarchaeota (Jolivet et al, 2003;Simon et al, 2005;Pikuta et al, 2007), the addition of rifampicin (100 mg ml À1 ), an antibiotic agent inactivating prokaryotic DNA-dependent RNA polymerase, completely inhibited CO 2 fixation, whereas there was no toxic effect of radicicol (20 mg ml À1 ), a natural product that inhibits DNA topoisomerase IV of some thermophilic crenarchaea (Gadelle et al, 2005). Depletion of oxygen in the deep seawater samples by addition of sulfide caused a slight decrease in primary production rates compared with untreated control (P ¼ 0.018).…”

Ionizing Radiation and Life

“…Due to this extreme radioresistance, as well as resilience to desiccation, hydrogen peroxide, and UV radiation, D. radiodurans is commonly used as a model strain for microorganisms able to survive on the martian surface (e.g., Richmond et al, 1999;Horneck, 2000;Pavlov et al, 2002;Dartnell et al, 2007a;de La Vega et al, 2007). More recently, strains of a hyperthermophilic archaeon Thermococcus, isolated from a submarine hydrothermal vent environment, have been found with a radiation resistance approaching that of D. radiodurans ( Jolivet et al, 2003( Jolivet et al, , 2004.…”