Abstract
A new mesophilic sulphate-reducing bacterium, designated strain DvO5 T (T=type strain), was isolated from the outermost sulphate reduction-positive most-probable-number tube (10 −6 dilution) of an activated sludge sample, which had been oxygenated at 100% air saturation for 120 h. The motile, Gram-negative, curved 1 by 2–5 μm and non-spore-forming cells of strain DvO5 T existed singly or in chains. Strain DvO5 T grew optimally at 29 °C, pH 6.9 and 0.05% (w/v) NaCl in a medium containing lactate, sulphate and yeast extract. Sulphite, thiosulphate and elemental sulphur also served as electron acceptors whereas nitrate, nitrite or ferric iron were not reduced. Lactate, pyruvate, H 2 (with acetate as carbon source), ethanol and glycerol efficiently supported growth as electron donors. Pyruvate and malate were fermented. Strain DvO5 T reduced oxygen by oxidising endogenous polyglucose at rates ranging from 0.4 to 6.0 nmol O 2/mg protein min depending on the oxygen concentration, the highest rates being observed at atmospheric oxygen saturation. The G+C content of the DNA was 57.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain DvO5 T was a member of the genus Desulfovibrio with D. magneticus (98.2% 16S rRNA gene sequence similarity) and D. burkinensis (97.5% 16S rRNA gene sequence similarity) being its closest relatives among validly described species. A similar phylogenetic affiliation was obtained by sequence analyses of the genes encoding the alpha and the beta subunit of dissimilatory sulphite reductase ( dsrAB) as well as the alpha subunit of adenosine-5′-phosphosulphate reductase ( apsA) of strain DvO5 T. On the basis of genotypic and phenotypic characteristics, strain DvO5 T (DSM 16695 T, JCM 12613 T) is proposed as the type strain of a new species, Desulfovibrio aerotolerans sp. nov.
Published Version
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