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Syntrophic associations from hypersaline soda lakes converting organic acids and alcohols to methane at extremely haloalkaline conditions
Author(s) -
Sorokin Dimitry Y.,
Abbas Ben,
Geleijnse Mitchell,
Kolganova Tatjana V.,
Kleerebezem Robbert,
van Loosdrecht Mark C. M.
Publication year - 2016
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.13448
Subject(s) - propionate , deltaproteobacteria , butyrate , methane , biology , sulfate , methanogenesis , firmicutes , environmental chemistry , fermentation , salinity , food science , chemistry , biochemistry , ecology , organic chemistry , gammaproteobacteria , 16s ribosomal rna , gene
Summary Until now anaerobic oxidation of VFA at high salt‐pH has been demonstrated only at sulfate‐reducing conditions. Here, we present results of a microbiological investigation of anaerobic conversion of organic acids and alcohols at methanogenic conditions by syntrophic associations enriched from hypersaline soda lakes in Central Asia. Sediment incubation experiments showed active, albeit very slow, methane formation from acetate, propionate, butyrate and C 2 C 4 alcohols at pH 10 and various levels of salinity. Enrichments of syntrophic associations using hydrogenotrophic members of the genus Methanocalculus from soda lakes as partners resulted in several highly enriched cultures converting acetate, propionate, butyrate, benzoate and EtOH to methane. Most syntrophs belonged to Firmicutes , while the propionate‐oxidizer formed a novel lineage within the family Syntrophobacteraceae in the Deltaproteobacteria . The acetate‐oxidizing syntroph was identified as ‘ Ca . Syntrophonatronum acetioxidans’ previously found to oxidize acetate at sulfate‐reducing conditions up to salt‐saturating concentrations. Butyrate and a benzoate‐degrading syntrophs represent novel genus‐level lineages in Syntrophomonadales which are proposed as Candidatus taxons ‘Syntrophobaca’, ‘Syntrophocurvum’ and ‘Syntropholuna’. Overall, despite very slow growth, the results indicated the presence of a functionally competent syntrophic community in hypersaline soda lakes, capable of efficient oxidation of fermentation products to methane at extremely haloalkaline conditions.