Abstract
A Gram-negative, facultatively anaerobic, chemo-organotrophic, non-pigmented, slowly growing bacterium was isolated from acidic Sphagnum peat and designated strain TPB6017T. Cells of this strain are long rods that multiply by normal cell division and are motile by means of a single flagellum. They grow under reduced oxygen tension and under anoxic conditions and ferment sugars and several polysaccharides including amorphous and crystalline cellulose. Strain TPB6017T is a psychrotolerant acidophile capable of growth between pH 3.0 and 7.5 (optimum 4.5-5.0) and at 4-35°C (optimum 20-28°C). It is extremely sensitive to salt stress; growth is inhibited at NaCl concentrations above 0.1% (w/v). The major fatty acids are iso-C15:0 and iso-C17:1ω9c; the polar lipids are phosphatidylethanolamine and a number of phospho- and aminophospholipids with an unknown structure. The quinone is MK-8. The DNA G+C content is 57.6 mol %. Comparative 16S rRNA gene analysis revealed that strain TPB6017T is a member of subdivision 1 of the phylum Acidobacteria and belongs to a phylogenetic lineage defined by acidophilic aerobic chemo-organotroph Acidobacterium capsulatum (92.3% sequence similarity). However, cell morphology, type of flagellation, absence of pigment, difference in fatty acid and polar lipid composition, possession of a cellulolytic capability, inability to grow under fully oxic conditions and good growth in anoxic conditions distinguished strain TPB6017T from A. capsulatum. Therefore, we propose a novel genus and a novel species, Telmatobacter bradus gen. nov., sp. nov., for this novel acidobacterium. Strain TPB6017T (=DSM 23630T = VKM B-2570T) is the type strain.