Further descriptive information

These organisms were found in the water and sediments of alkaline lakes in which sulfide is produced in the underlying sediments. Growth in the laboratory was studied in carbonate/bicarbonate buffered medium containing thiosulfate, sulfide, polysulfide, sulfur, and polythionates. All strains produce elemental sulfur from thiosulfate at the beginning of the exponential phase in batch culture; this sulfur vanishes later in growth. Tetrathion-ate and elemental sulfur were used by most strains. The pH optimum was 9-10. Ammonia, nitrite, and nitrate were used as nitrogen sources. Some strains reduced nitrate to nitrite under reduced O2 levels. The type strain of T. denitrificans, ALJD, is a facultative anaerobe able to grow with thiosulfate and nitrous oxide as electron donor and acceptor, respectively (Sorokin et al., 2001a).

Analysis of the 16S rDNA sequence of the type strains of T. versutus, T. denitrificans, and T. nitratis showed that the genus Thioalkalivibrio belongs to the Gammaproteobacteria; two species of the genus Ectothiorhodospira (anaerobic purple sulfur bacteria) were their closest relatives (Sorokin et al., 2001a).

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