Title
Methanonatronarchaeum thermophilum gen. Nov., sp. nov. and ’Candidatus methanohalarchaeum thermophilum’, extremely halo(natrono)philic methyl-reducing methanogens from hypersaline lakes comprising a new euryarchaeal class Methanonatronarchaeia classis nov.
Author
Sorokin, Dimitry Y. (TU Delft BT/Environmental Biotechnology; Russian Academy of Sciences) 
Merkel, Alexander Y. (Russian Academy of Sciences)
Abbas, B.A. (TU Delft BT/Environmental Biotechnology)
Makarova, Kira S. (National Institutes of Health)
Rijpstra, W. Irene C. (Universiteit Utrecht)
Koenen, M. (Universiteit Utrecht)
Sinninghe Damsté, Jaap S. (Universiteit Utrecht)
Galinski, Erwin A. (Universität Bonn)
Koonin, Eugene V. (National Institutes of Health)
van Loosdrecht, Mark C.M. (TU Delft BT/Environmental Biotechnology)
Date
2018-07-01
Abstract
Methanogenic enrichments from hypersaline lakes at moderate thermophilic conditions have resulted in the cultivation of an unknown deep lineage of euryarchaeota related to the class Halobacteria. Eleven soda lake isolates and three salt lake enrichment cultures were methyl-reducing methanogens that utilize C1 methylated compounds as electron acceptors and H2 or formate as electron donors, but they were unable to grow on either substrates alone or to form methane from acetate. They are extreme halophiles, growing optimally at 4 M total Na+ and the first representatives of methanogens employing the ‘salt-in’ osmoprotective mechanism. The salt lake subgroup is neutrophilic, whereas the soda lake isolates are obligate alkaliphiles, with an optimum around pH 9.5. Both grow optimally at 50°C. The genetic diversity inside the two subgroups is very low, indicating that the soda and salt lake clusters consist of a single genetic species each. The phylogenetic distance between the two subgroups is in the range of distant genera, whereas the distance to other euryarchaea is below 83 % identity of the 16S rRNA gene. These isolates and enriched methanogens, together with closely related environmental clones from hypersaline habitats (the SA1 group), form a novel class-level clade in the phylum Euryarchaeota. On the basis of distinct phenotypic and genetic properties, the soda lake isolates are classified into a new genus and species, Methanonatronarchaeum thermophilum, with the type strain AMET1T (DSM 28684T=NBRC 110805T=UNIQEM U982T), and the salt lake methanogens into a candidate genus and species ‘Candidatus Methanohalarchaeum thermophilum’. These organisms are proposed to form novel family, order and class Methanonatronarchaeaceae fam. nov., Methanonatronarchaeales ord. nov. and Methanonatronarchaeia classis nov., within the phylum Euryarchaeota.
Subject
Hypersaline
Methanogenesis
Methanonatronarchaeia
Methyl-reducing pathway
Soda lakes
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http://resolver.tudelft.nl/uuid:b966124c-aa39-4369-bbfa-91c01b051bac
DOI
https://doi.org/10.1099/ijsem.0.002810
Embargo date
2019-07-01
ISSN
1466-5026
Source
International Journal of Systematic and Evolutionary Microbiology, 68 (7), 2199-2208
Bibliographical note
Accepted Author Manuscript
Part of collection
Institutional Repository
Document type
journal article
Rights
© 2018 Dimitry Y. Sorokin, Alexander Y. Merkel, B.A. Abbas, Kira S. Makarova, W. Irene C. Rijpstra, M. Koenen, Jaap S. Sinninghe Damsté, Erwin A. Galinski, Eugene V. Koonin, Mark C.M. van Loosdrecht