Desulfuromonas thiophila sp. nov., a New Obligately Sulfur-Reducing Bacterium from Anoxic Freshwater Sediment

Abstract

A mesophilic, acetate-oxidizing, sulfur-reducing bacterium, strain NZ27T, was isolated from anoxic mud from a freshwater sulfur spring. The cells were ovoid, motile, and gram negative. In addition to acetate, the strain oxidized pyruvate, succinate, and fumarate. Sulfur flower could be replaced by polysulfide as an electron acceptor. Ferric nitrilotriacetic acid was reduced in the presence of pyruvate; however, this reduction did not sustain growth. These phenotypic characteristics suggested that strain NZ27T is affiliated with the genus Desulfiromonas. A phylogenetic analysis based on the results of comparative 16s ribosomal DNA sequencing confirmed that strain NZ27T belongs to the Desulfiromonas cluster in the recently proposed family "Geobacteraceae" in the delta subgroup of the Proteobacteria. In addition, the results of DNA-DNA hybridization studies confirmed that strain NZ27T represents a novel species. Desulfiromonas thiophila, a name tentatively used in previous publications, is the name proposed for strain NZ27T in this paper.Bacteria that are able to grow by linking the oxidation of acetate to the reduction of elemental sulfur have been known since Pfennig and Biebl described the isolation of Desulfiromonas acetoxidans in 1976 (26). While a number of strains of the genus Desulfuromonas have been isolated and deposited in culture collections (33), Desulfuromonas acetoxidans (with type strain DSM 864) is the only species that has been validly published previously (26). Recently, two other species, the freshwater organism '(Desulfuromonas acetexigens" (with type strain 2873 [ = DSM 13971) (10) and the marine organism "Desulfuromonas palmitatis" (with type strain SDBYl [= ATCC 517011) (4), have been characterized. Data obtained for a second freshwater strain (isolate NZ27T), which was tentatively named Desulfuromonas thiophila have been published in review articles (31,33). However, a valid description of this strain has not been published previously.In this paper we present a detailed characterization of Desulfuromonas thiophila NZ27T, including a phenotypic description, the phylogenetic affiliation of this organism with known species of the recently described family ('Geobacteraceae" (19), and the results of DNA-DNA hybridization studies performed with closely related species of the genus Desulfiromonas. Based on the genotypic and phenotypic differences between strain NZ27 and the other members of the genus Desulfuromonas, we propose that strain NZ27 is the type strain of a new species, Desulfuromonas thiophila. MATERIALS AND METHODSSource of the organism. Sulfur-reducing strain NZ27T was isolated in 1979 by Bache and Pfennig (1) from anoxic mud from a freshwater sulfur spring at Ngawha Springs in Moerewa, New Zealand (North Island).Media and cultivation conditions. The basal medium used for cultivation of freshwater strain NZ27T contained (per liter) 0.5 g of NaCI, 0.2 g of MgCI, -6H,O, 0.1 g of CaCI, -2H,O, 0.1 g of NH4Cl, 0.2 g of KH2P04, and 0.25 g of KCl. After the medium was autoclaved and cooled u...

Geobacter hydrogenophilus, Geobacter chapellei and Geobacter grbiciae, three new, strictly anaerobic, dissimilatory Fe(III)-reducers.

“…The GjC contents of strains TACP-2 T and TACP-5 were also almost identical to each other, but differed from that of Geobacter metallireducens by 1n5 % and from that of strain H-2 T by about 1 %. It should be noted that, although the GjC content determined here for D. acetoxidans was similar to values published previously (Finster et al, 1997), the value obtained for Geobacter metallireducens strain GS-15 T was slightly higher than that published previously. This difference was probably a function of the different method employed in this study (HPLC, as opposed to the thermal denaturation method employed previously by Lovley et al, 1993).…”

Microbial Manganese and Sulfate Reduction in Black Sea Shelf Sediments

“…The clone-type A3Mn2 from station I was affiliated with the Desulfuromonas-Pelobacter cluster which contains numerous Fereducing bacterial species (16,32). However, several of the species most closely related to the clone-type A3Mn2 from station I have been found to reduce only soluble Fe(III) complexes and not ferrihydrite (21,32). The Mn-reducing capabilities of these organisms have not been reported.…”

The Family Desulfuromonadaceae

“…With a level of DNA relatedness of less than 30 %, the isolates were classified into three Desulfuromusa species. Finster et al (1997) performed DNA-DNA hybridization studies on four Desulfuromonas isolates. Of these, the highest degree of relatedness was between D. acetexigens and D. palmitatis (37 %), followed by D. palmitatis and D. thiophila (31 %), D. acetoxidans and D. thiophila (31 %) and the remaining combinations were 20-22 %.…”