Diversity and origin of Desulfovibrio species: phylogenetic definition of a family

Abstract

The different nutritional properties of several Desulfovibrio desulfuricans strains suggest that either the strains are misclassified or there is a high degree of phenotypic diversity within the genus Desulfovibrio. The obligately anaerobic, dissimilatory, sulfate-reducing bacteria utilize sulfate as their terminal electron acceptor and derive their energy for growth from the oxidation of organic compounds and hydrogen gas (27). Among the genera of sulfate-reducing bacteria, perhaps the most thoroughly studied species are classified in the genus Desulfovibrio. The Desulfovibrio species which have been characterized are nutritionally similar; they are readily enriched with lactate or hydrogen and utilize only a few other substrates (38). Diagnostically, Desulfovibrio species test positive (with some exceptions) for the sulfite reductase desulfoviridin and contain the unique tetraheme cytochrome C3 (27). These observations have contributed to the notion that although the sulfate-reducing bacteria are ecologically very significant, they comprise a small and nutritionally limited group. However, recent isolations and descriptions of new genera have dispelled this view (38). At present, more than 10 genera of sulfate-reducing eubacteria (one of which is affiliated with gram-positive bacteria) and an extremely thermophilic sulfate-reducing archaebacterium have been described (36, 39).While the nutritional versatility and phylogenetic diversity of the sulfate-reducing bacteria have been established, questions of relatedness among species of the genus Desulfovibrio remain unanswered. Postgate has stated that the "taxonomic picture" of the genus is "imperfect" (27

Haloterrigena thermotolerans sp. nov., a halophilic archaeon from Puerto Rico.

“…Additional studies will be required to reassess the taxonomic status of the two genera. Similarity percentages between the PR5 T sequence and the type strains of Haloterrigena turkmenica, Natrinema pellirubrum and Natrinema pallidum were 96n2, 96n6 and 96n2 %, respectively, sufficiently high to enable classification within either of these genera, but sufficiently low to warrant the creation of a separate taxon at the species level (Devereux et al, 1990).…”

Characterization of the marine propionate-degrading, sulfate-reducing bacterium Desulfofaba fastidiosa sp. nov. and reclassification of Desulfomusa hansenii as Desulfofaba hansenii comb. nov.

“…The inability of strain P2 T to oxidize acetate completely to CO 2 is interesting, considering its phylogenetic affiliation to the complete oxidizers such as Desulfonema, Desulfococcus and Desulfosarcina. Until recently, incompletely oxidizing sulfate reducers grouped separately from the complete oxidizers, with only one exception, 'Desulfobotulus sapovorans' (=[Desulfovibrio] sapovorans) (Devereux et al, 1989(Devereux et al, , 1990. In 1999, however, two incomplete sulfate reducers, Desulfofaba gelida and Desulfofrigus fragile, whose closest relatives were members of the Desulfosarcina group, were isolated.…”

Description of Two New Thermophilic Desulfotomaculum spp., Desulfotomaculum putei sp. nov., from a Deep Terrestrial Subsurface, and Desulfotomaculum luciae sp. nov., from a Hot Spring

“…Strains TH-11" and SLTr are also clearly distinguished phylogenetically from each other and from the most closely related members of the genus for which sequences are available, with the closest relatives exhibiting about 95% sequence similarity. Levels of sequence similarity of <98% indicate that the phylogenetic distance is great enough for placement in a separate species (7,12), and establishment of a new species should require phenotypic as well as phylogenetic differences (47).…”