Rubribacterium polymorphum gen. nov., sp. nov., a novel alkaliphilic nonsulfur purple bacterium from an Eastern Siberian soda lake

• Published in: Microbiology (New York) 2009-12, Vol.78 (6), p.732-740
• Main Authors: Boldareva, E. N, Moskalenko, A. A, Makhneva, Z. K, Tourova, T. P, Kolganova, T. V, Gorlenko, V. M
• Format: Article
• Language: English
• Subjects: Bacteria; Biomedical and Life Sciences; Experimental Articles; Life Sciences; Medical Microbiology; Microbiology; Rhodobacter
• ISSN: 0026-2617; 1608-3237
• DOI: 10.1134/S0026261709060101

An alkaliphilic nonsulfur purple bacterial (NPB) strain “Green” was isolated from sediments of the littoral zone of the soda lake (mineralization 22 g/l, pH 9.5) in the Barguzin River valley (Eastern Siberia). The cells of the new isolate are ovoid or polymorphic at latter stages. The photosynthetic membrane structures are of vesicular type. Bacteriochlorophyll a and carotenoids of both spheroidene and spirilloxanthin type are the photosynthetic pigments. Two light-harvesting systems (LH1 and LH2) are present. The new isolate is a photoheterotroph and a facultative aerobe. It grows well in the dark on organic substrates; anaerobic phototrophic growth is poor. The isolate is alkaliphilic with pH optimum of 8.5-9.5. The most abundant cell growth occurred at 5-40 g/l NaCl (optimum at 10 g/l) and 30 °C. The DNA G+C base content was 69.9 mol %. Analysis of 16S rRNA gene sequences revealed a 10% difference with the most closely related NPB (Rhodobacter species). Rubrimonas cliftoensis, a bacteriochlorophyll a-containing bacterium, is the closest relative (93.3% similarity). It is proposed that strain “Green” should be placed in the new genus and new species Rubribacterium polymorphum gen. nov., sp. nov. GenBank accession number: 16S rRNA-EU857676.