RT Journal Article SR Electronic(1) A1 Ollivier, Bernard A1 Fardeau, Marie-Laure A1 Cayol, Jean-Luc A1 Magot, Michel A1 Patel, Bharat K. C. A1 Prensier, GĂ©rard A1 Garcia, Jean-LouisYR 1998 T1 Methanocalculus halotolerans gen. nov., sp. nov., isolated from an oil-producing well JF International Journal of Systematic and Evolutionary Microbiology, VO 48 IS 3 SP 821 OP 828 DO https://doi.org/10.1099/00207713-48-3-821 PB Microbiology Society, SN 1466-5034, AB Two irregular coccoid methanogens designated SEBR 4845Tand FR1T were isolated from an oilfield in Alsace, France. Strain SEBR 4845T(T = type strain) is a hydrogenotrophic halotolerant methanogen, which grows optimally at 5% NaCI (w/v) and tolerates up to 12% NaCI. It does not use methylated compounds and therefore cannot be ascribed to any of the known genera of the halophilic methylotrophic methanogens. It differs from hydrogenotrophic members of the orders Methanococcales and Methanomicrobia les in the NaCI growth range (0-12% NaCI), which is the widest reported to date for any hydrogenotrophic methanogen. 16S rRNA gene sequence analysis indicated that strain SEBR 4845Tis a novel isolate for which a new genus is proposed, Methanocalculus halotolerans gen. nov., sp. nov. (= OCM 470T) that might be indigenous to the oilfield ecosystem. Strain FR1T (= OCM 471) is a moderately halophilic methanogen which grows optimally at 10% NaCI and tolerates up to 20% NaCI. It grows on trimethylamine and methanol as carbon and energy sources. The G+C content of its DNA is 43 mol%. It is therefore phenotypically and genotypically related to members of the genus Methanohalophilus. This report provides evidence that methylotrophic and hydrogenotrophic, but not aceticlastic methanogens are present in a saline subsurface oilfield environment, as already observed in surface saline to hypersaline environments., UL https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/00207713-48-3-821