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A phylogenetically novel aerobic bacterium was isolated from an anaerobic–aerobic sequential batch reactor operated under enhanced biological phosphorus removal conditions for wastewater treatment. The isolation strategy used targeted slowly growing polyphosphate-accumulating bacteria by combining low-speed centrifugations and prolonged incubation on a low-nutrient medium. The isolate, designated strain T-27T, was a Gram-negative, rod-shaped aerobe. Cells often appeared to divide by budding replication. Strain T-27T grew at 25–35 °C with an optimum growth temperature of 30 °C, whilst no growth was observed below 20 °C or above 37 °C within 20 days incubation. The pH range for growth was 6·5–9·5, with an optimum at pH 7·0. Strain T-27T was able to utilize a limited range of substrates, such as yeast extract, polypepton, succinate, acetate, gelatin and benzoate. Neisser staining was positive and 4,6-diamidino-2-phenylindole-stained cells displayed a yellow fluorescence, indicative of polyphosphate inclusions. Menaquinone 9 was the major respiratory quinone. The cellular fatty acids of the strain were mainly composed of iso-C15 : 0, C16 : 1 and C14 : 0. The G+C content of the genomic DNA was 66 mol%. Comparative analyses of 16S rRNA gene sequences indicated that strain T-27T belongs to candidate division BD (also called KS-B), a phylum-level lineage in the bacterial domain, to date comprised exclusively of environmental 16S rDNA clone sequences. Here, a new genus and species are proposed, Gemmatimonas aurantiaca (type strain T-27T=JCM 11422T=DSM 14586T) gen. nov., sp. nov., the first cultivated representative of the Gemmatimonadetes phyl. nov. Environmental sequence data indicate that this phylum is widespread in nature and has a phylogenetic breadth (19 % 16S rDNA sequence divergence) that is greater than well-known phyla such as the Actinobacteria (18 % divergence).
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