No abstract

An obligately anaerobic, spore-forming, acidophilic sulfate-reducing bacterium, strain SJ4(T), was isolated from an acid mining effluent decantation pond sediment sample (pH around 3.0). Cells were Gram negative, non-motile, curved rods occurring singly. Strain SJ4(T) grew at pH 3.6-5.5 with an optimum at pH 5.2. Strain SJ4(T) utilized H(2), lactate, pyruvate, glycerol, glucose, and fructose as electron donors. Lactate and glucose were weakly used. Sulfate was used as electron acceptors, but not sulfite, elemental sulfur, arsenate (V), and fumarate. The G + C content of genomic DNA was 42.3 mol% (HPLC). 16S rRNA gene sequence analysis indicated that strain SJ4(T) belonged to the genus Desulfosporosinus within the family Peptococcaceae in the phylum Firmicutes. The level of 16S rRNA gene sequence similarity with other Desulfosporosinus species was 94.7-96.2%, D. orientis DSM 765(T) (similarity of 96.2%) and D. auripigmenti DSM 13351(T) (similarity of 95%) being its closest relatives. DNA-DNA relatedness values with D. orientis and D. auripigmenti were 16.5 and 31.8%, respectively. On the basis of phenotypic, phylogenetic, and genetic characteristics, strain SJ4(T) represents a novel species within the genus Desulfosporosinus, for which the name Desulfosporosinus acidiphilus sp. nov. is proposed. The type strain is SJ4(T) (=DSM 22704(T) = JCM 16185(T)).

No abstract

T ) differed from D. zosterae not only phylogenetically, but also genomically (DNA-DNA reassociation value between the two bacteria was 23?8 %) and phenotypically. This isolate is therefore proposed as the type strain of a novel species of the genus Desulfovibrio, Desulfovibrio hydrothermalis sp. nov.Deep-sea hydrothermal vents are among the most productive ecosystems on Earth, where unusual animal and microbial communities are able to survive the harsh combinations of toxic chemicals, high pressures, high temperatures and total darkness. This high biomass productivity is based largely on the activity of ectoand endosymbiotic associations of chemolithotrophic micro-organisms and vent fauna (Jeanthon, 2000;Polz & Cavanaugh, 1995). Microbial hydrothermal vent communities also include free-living bacteria associated with the discharged vent fluids, free-living microbial mats and micro-organisms within the deep-sea hydrothermal vent plume (Karl, 1995). Although increasing attention has been paid to the thermophilic and hyperthermophilic microorganisms that inhabit deep-sea hydrothermal vents, because of their high biotechnological potential, mesophilic and psychrophilic micro-organisms are known to be significant components of the microbial community along the physico-chemical gradient of the vent ecosystem (Jeanthon, 2000). The occurrence of mesophilic sulfatereducing bacteria (SRB) was made evident by (i) significant sulfate-reduction activities in vent sediments (Elsgaard et al., 1994;Jørgensen et al., 1992) and (ii) their isolation from various samples collected at different hydrothermal sites (Elsgaard et al., 1995). However, none of them has yet been characterized.Here, we report the isolation from deep-sea hydrothermal chimneys of SRB that are phylogenetically similar to Desulfovibrio profundus (Bale et al., 1997) and the characterization of a novel mesophilic, barophilic species (strain AM13 T ) of the genus Desulfovibrio, Desulfovibrio hydrothermalis sp. nov.Strains BL5, H9, H1 and AM13T were isolated from a deep-sea hydrothermal chimney sample stored in sea water at 4˚C until processing. The GenBank accession number for the 16S rDNA sequence of strain AM13T is AF458778.