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New Taxa - Proteobacteria

Desulfocella halophila gen. nov., sp. nov., a halophilic, fatty-acid-oxidizing, sulfate-reducing bacterium isolated from sediments of the Great Salt Lake

Kristian K. Brandt, Bharat K. C. Patel, Kjeld Ingvorsen

  • Author for correspondence: Kjeld Ingvorsen. Tel: +45 89 42 32 45. Fax: +45 86 12 71 91. e-mail: Kjeld.Ingvorsen{at}biology.aau.dk

    • International Journal of Systematic Bacteriology 1999; 49(1):193–200 · https://doi.org/10.1099/00207713-49-1-193

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    Summary auto-generated

    Researchers isolated a new halophilic, sulfate-reducing bacterium designated Desulfocella halophila from Great Salt Lake sediments. This gram-negative vibrio oxidizes straight-chain fatty acids (C4-C16) and branched fatty acids incompletely to acetate, using sulfate as the sole electron acceptor. The organism grows optimally at 34°C and 4-5% NaCl but tolerates 2-19% NaCl, with optimal pH 6.5-7.3. Phylogenetic analysis of 16S rRNA gene sequences revealed the strain belongs to the family Desulfobacteriaceae within the delta-subclass of Proteobacteria and represents a new genus and species. The bacterium has a G+C content of 35.0 mol% and does not require vitamins, though yeast extract stimulates growth. With butyrate as substrate, the generation time was approximately 28 hours in defined medium and 20 hours in complex medium. This represents the first very halotolerant sulfate-reducer described that can utilize long-chain fatty acids as electron donors.

    Key findings

    • Desulfocella halophila is the first halophilic sulfate-reducing bacterium capable of oxidizing long-chain fatty acids (C4-C16) and L-alanine as electron donors, oxidizing them incompletely to acetate.
    • The organism is highly halotolerant, growing between 2-19% NaCl with optimum at 4-5% NaCl, making it well-adapted to hypersaline environments like the Great Salt Lake.
    • 16S rRNA phylogenetic analysis identifies D. halophila as a novel genus within the family Desulfobacteriaceae of delta-Proteobacteria, distinct from known sulfate-reducing bacteria genera.
    • The low G+C content of 35.0 mol% and unique fatty acid profile distinguish this organism from its closest described relatives.
    • Butyrate is incompletely oxidized to acetate according to the equation: 2 butyrate + sulfate → 4 acetate + hydrogen sulfide, with doubling times of 28 h in defined medium.

    This summary was generated automatically from the article PDF and is not part of the original publication. Refer to the PDF for the authoritative text.

    Abstract

    A new halophilic sulfate-reducing bacterium, strain GSL-But2T, was isolated from surface sediment of the Southern arm of the Great Salt Lake, UT, USA. organism grew with a number of straight-chain fatty acids (C4-C16), 2-methylbutyrate, l-alanine and pyruvate as electron donors. Butyrate was oxidized incompletely to acetate. Sulfate, but not sulfite or thiosulfate, serv as an electron acceptor. Growth was observed between 2 and 19% (w/v) NaCl with an optimum at 4-5% (w/v) NaCl. The optimal temperature and pH for growth were around 34°C and pH 6.5-7.3, respectively. The generation time under optimal conditions in defined medium was around 28 h, compared to 20 h in complex medium containing yeast extract. The G+C content was 35.0 mol%. 16S rRNA gene sequence analysis revealed that strain GSL-But2Tbelongs to the family Desulfobacteriaceae within the delta-subclass of the Proteobacteria and suggested that strain GSL-But2Trepresents a member of new genus. The name Desulfocella halophila gen. nov., sp. nov. is proposed for this organism. The type strain of D. halophila is strain GSL-But2T(= DSM 117 = ATCC 700426T).