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

Department of Microbial Ecology, Bldg 540, Institute of Biological Sciences, University of Aarhus, 8000 Aarhus C, Denmark Correspondence Kai Finster Kai.Finster{at}biology.au.dk A rod-shaped, slightly curved sulfate reducer, designated strain P2 T , was isolated from the sulfate–methane transition zone of a marine sediment. Cells were motile by means of a single polar flagellum. The strain reduced sulfate, thiosulfate and sulfite to sulfide and used propionate, lactate and 1-propanol as electron donors. Strain P2 T also grew by fermentation of lactate. Propionate was oxidized incompletely to acetate and CO 2 . The DNA G+C content was 48·8 mol%. Sequence analysis of the small-subunit rDNA and the dissimilatory sulfite reductase gene revealed that strain P2 T was related to the genera Desulfonema , Desulfococcus , Desulfosarcina , ‘ Desulfobotulus ’, Desulfofaba , Desulfomusa and Desulfofrigus . These genera include incomplete as well as complete oxidizers of substrates. Strain P2 T shared important morphological and physiological traits with Desulfofaba gelida and Desulfomusa hansenii , including the ability to oxidize propionate incompletely to acetate. The 16S rRNA gene similarities of P2 T to Desulfofaba gelida and Desulfomusa hansenii were respectively 92·9 and 91·5 %. Combining phenotypic and genotypic traits, we propose strain P2 T to be a member of the genus Desulfofaba . The name Desulfofaba fastidiosa sp. nov. (type strain P2 T =DSM 15249 T =ATCC BAA-815 T ) is proposed, reflecting the limited number of substrates consumed by the strain. In addition, the reclassification of Desulfomusa hansenii as a member of the genus Desulfofaba , Desulfofaba hansenii comb. nov., is proposed. A common line of descent and a number of shared phenotypic traits support this reclassification. Abbreviations: DSR, dissimilatory sulfite reductase Published online ahead of print on 28 November 2003 as DOI 10.1099/ije.0.02820-0. The GenBank/EMBL/DDBJ accession numbers for the 16S rDNA and partial DSR gene sequences of strain P2 T are AY268891 and AY268892 . Phase-contrast micrographs showing cells of strain P2 T and a DSR sequence-based phylogenetic tree are available as supplementary material in IJSEM Online.