title: Methanosalsum natronophilum sp. nov., and Methanocalculus alkaliphilus sp. nov., haloalkaliphilic methanogens from hypersaline soda lakes.
abstract: Two groups of haloalkaliphilic methanogenic archaea were dominating in enrichments from hypersaline soda lake sediments at pH 10. At moderate salt concentrations with formate or H2 as electron donor, methanogens belonging to the genus Methanocalculus were enriched, while at high salt concentrations with methylated substrates, a group related to Methanosalsum zhilinae was dominating. For both groups, several pure cultures were obtained including the type strains AMF2T for the Methanocalculus group and AME2T for the Methanosalsum group. The Methanocalculus group is characterized by lithoheterotrophic growth with either formate (preferable substrate) or H2 at moderate salinity up to 1.5-2 M total Na+ and obligate alkaliphilic growth with an optimum at pH 9.5. According to phylogenetic analysis, the group also includes closely related strains isolated previously from the low-salt alkaline Lonar Lake. The novel Methanosalsum group is characterized by high salt tolerance (up to 3.5 M total Na+) and obligate alkaliphilic growth with an optimum at pH 9.5. It has a typical methylotrophic substrate profile, utilizing methanol, methylamines and dimethyl sulfide (at low concentrations) as methanogenic substrates. On the basis of physiological and phylogenetic data, it is proposed that the two groups of soda lake methanogenic isolates are assigned into two novel species, Methanocalculus alkaliphilus sp. nov. (type strain AMF2T = DSM 24457T = UNIQEM U859T) and Methanosalsum natronophilum sp. nov. (type strain AME2T = DSM 24634T = NBRC 110091T).
authors.affiliation: Winogradsky Institute of Microbiology, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia.|Department of Biotechnology, TU Delft, The Netherlands.
authors.forename: Dimitry Y
authors.initials: DY
authors.lastname: Sorokin
authors.affiliation: Department of Biotechnology, TU Delft, The Netherlands.
authors.forename: Ben
authors.initials: B
authors.lastname: Abbas
authors.affiliation: Winogradsky Institute of Microbiology, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Alexander Y
authors.initials: AY
authors.lastname: Merkel
authors.affiliation: Department of Marine Organic Biogeochemistry, NIOZ Netherlands Institute for Sea Research, The Netherlands.
authors.forename: W Irene C
authors.initials: WIC
authors.lastname: Rijpstra
authors.affiliation: Department of Earth Sciences - Geochemistry, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands.|Institute of Bioengineering, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Jaap S Sinninghe
authors.initials: JSS
authors.lastname: Damsté
authors.affiliation: Institute of Bioengineering, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Marina V
authors.initials: MV
authors.lastname: Sukhacheva
authors.affiliation: Department of Biotechnology, TU Delft, The Netherlands.
authors.forename: Mark C M
authors.initials: MCM
authors.lastname: van Loosdrecht
mesh_terms: D019641:DNA, Archaeal / Q000235:genetics; D019015:Geologic Sediments / Q000382:microbiology; D060106:Lakes / Q000382:microbiology*; D008055:Lipids / Q000737:chemistry; D017018:Methanomicrobiales / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D017019:Methanosarcinaceae / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012426:Russia; D054712:Salinity; D055049:Salt Tolerance; D017422:Sequence Analysis, DNA
chemical_list: D019641:DNA, Archaeal; D008055:Lipids; D012336:RNA, Ribosomal, 16S