title: A new ecological adaptation to high sulfide by a Hydrogenobacter sp. growing on sulfur compounds but not on hydrogen.
abstract: Thermophilic bacteria were isolated from a sulfide-rich, neutral hot spring in Iceland on gelrite minimal medium with 16 mM thiosulfate. The isolates were aerobic, obligate chemolithoautotrophs and used thiosulfate and sulfur as electron donors, producing sulfate from both substrates. No growth was observed with hydrogen as the sole electron donor, and no hydrogenase activity was detected. The cells were gram-negative and usually single, 4-5 microm long and 0.7 microm in diameter and formed sulfur globules after a few days of incubation. By SSU rRNA sequence comparisons, the bacterium was placed in the genus Hydrogenobacter with the closest relative to be Calderobacterium hydrogenophilum with 98.3% sequence similarity. This novel bacterium shows an ecological adaptation to high sulfide springs and is differentiated from its closest known relatives by lack of H2 oxidation, deposition of sulfur and lower growth temperature.
authors.affiliation: Prokaria Ltd., Reykjavik, Iceland.
authors.forename: S
authors.initials: S
authors.lastname: Skimisdottir
authors.forename: G O
authors.initials: GO
authors.lastname: Hreggvidsson
authors.forename: O
authors.initials: O
authors.lastname: Holst
authors.forename: J K
authors.initials: JK
authors.lastname: Kristjansson
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology; D001420:Bacteria, Aerobic / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D006864:Hydrogenase / Q000378:metabolism; D007055:Iceland; D008969:Molecular Sequence Data; D010641:Phenotype; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012335:RNA, Ribosomal / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013431:Sulfates / Q000378:metabolism*; D013440:Sulfides / Q000378:metabolism*; D013885:Thiosulfates / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D012335:RNA, Ribosomal; D013431:Sulfates; D013440:Sulfides; D013885:Thiosulfates; D006864:Hydrogenase