Downloaded from www.microbiologyresearch.org by IP: 54.70.40.11 On: Thu, 03 Jan 2019 03:01:42 Rhodovulum tesquicola sp. nov., a haloalkaliphilic purple non-sulfur bacterium from brackish steppe soda lakes Elena I. Kompantseva, 1 Anastasia V. Komova, 1 Andrey A. Novikov 2 and Nadezhda A. Kostrikina 1 Correspondence Elena Kompantseva elenamaxi@mail.ru 1 Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7-2, Moscow 117312, Russia 2 Gubkin Russian State University of Oil and Gas, Leninskiy Prospect 65, Moscow 119991, Russia Two strains of purple non-sulfur bacteria (A-36s T and A-51s) were isolated from brackish steppe soda lakes of southern Siberia. Genetically, the isolates were related most closely to the type strains of Rhodovulum steppense and Rhodovulum strictum, from which they differed at the species level (98.5 % 16S rRNA gene sequence similarity, 40–53 % DNA–DNA relatedness). Cells of the two strains were ovoid to rod-shaped, 0.4–0.8 mm wide and 1.0–2.5 mm long, and motile by means of a polar flagellum. They contained internal photosynthetic membranes of vesicular type and photosynthetic pigments (bacteriochlorophyll a and carotenoids of the spheroidene series). The strains were obligate haloalkaliphiles, growing over wide ranges of salinity (0.3–10.0 % NaCl) and pH (7.5–10.0), with growth optima at 1.0–3.0 % NaCl and pH 8.5–9.0. Photoheterotrophic and chemoheterotrophic growth occurred with a number of organic compounds and biotin, p-aminobenzoate, thiamine and niacin as growth factors. No anaerobic respiration on nitrite, nitrate or fumarate and no fermentation were demonstrated. The strains grew photolithoautotrophically and chemolithoautotrophically with sulfide, sulfur and thiosulfate, oxidizing them to sulfate. Sulfide was oxidized via deposition of extracellular elemental sulfur. No growth with H 2 as the electron donor was observed. The major fatty acid was C 18 : 1 (78 %). The major quinone was ubiquinone Q-10. The DNA G+C content of strain A-36s T was 65.4 mol% (T m ). According to genotypic and phenotypic characteristics, the investigated strains were assigned to a novel species of the genus Rhodovulum, for which the name Rhodovulum tesquicola sp. nov. is proposed. The type strain is A-36s T (5VKM B-2491 T 5ATCC BAA-1573 T ), which was isolated from steppe soda lake Sul’fatnoe (Zabaikal’skii Krai, southern Siberia, Russia). In the cryoarid zone of Central Asia, small shallow brackish soda lakes are abundant. Specific features of these lakes distinguishing them from better investigated saline and hypersaline alkaline water bodies are their lower mineraliza- tion, smaller salt reserves and highly unstable hydrochemical regime (Kompantseva et al., 2005, 2007). We previously showed that weakly mineralized soda lakes represent a particular type of habitat that has specific autochthonous microbial communities; this habitat differs both from highly mineralized soda lakes and from shallow saline water bodies of thalassic origin (Kompantseva et al., 2007). The specificity of these lakes is also demonstrated by the abundance of novel forms of anoxygenic phototrophic bacteria that have not previously been found in other ecosystems (Kompantseva et al., 2007, 2010). The present article describes a novel species of purple non-sulfur bacterium inhabiting brackish soda lakes of southern Siberia. During investigation of the steppe soda lakes of the cryoarid zone of Central Asia, many strains of purple non-sulfur bacteria were isolated and phylogenetic analysis was performed (Kompantseva et al., 2009). According to 16S rRNA gene sequencing results, the isolates formed two clusters within the genus Rhodovulum. The majority of the strains formed one cluster, which was described as a novel species, Rhodovulum steppense (Kompantseva et al., 2010). The other cluster comprised a single strain, A-36s T , isolated from Sul’fatnoe lake, Buryat Republic. An additional strain, designated A-51s, which was very closely related to strain A- 36s T (100 % 16S rRNA gene sequence similarity), was isolated from Nizhnii Mukei lake, Zabaikal’skii Krai. The two strains shared 98.5 % 16S rRNA gene sequence similarity The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequences of strains A-36s T and A-51s are EU741685 and JN165105, respectively. Five supplementary figures are available with the online version of this paper. International Journal of Systematic and Evolutionary Microbiology (2012), 62, 2962–2966 DOI 10.1099/ijs.0.035857-0 2962 035857 G 2012 IUMS Printed in Great Britain