Rhodomicrobium udaipurense sp. nov., a psychrotolerant, phototrophic alphaproteobacterium isolated from a freshwater stream

Abstract

Two strains (JA643T and JA755) of Gram-stain-negative, facultatively anaerobic phototrophic, bacteria capable of growth at low temperatures (10–15 °C) were isolated from freshwater streams from different geographical regions of India. Both strains contain bacteriochlorophyll a and carotenoids of the spirilloxanthin series. Phosphatidylethanolamine, phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, an unidentified phospholipid (PL), unidentified amino lipids (AL1–AL6, AL9) and an unidentified lipid (L1) were the polar lipids present in both strains. The major cellular fatty acid was C18 : 1ω7c (76–79 % of the total). Bacteriohopane derivatives (BHD1,2), unidentified hopanoids (UH1–5), diplopterol (DPL) and diploptene (DPE) were the major hopanoids of both strains. The DNA G+C content was 64.2–64.5 mol%. 16S rRNA gene sequence-based phylogenetic analysis showed that both strains are closely related to the genus Rhodomicrobium and clustered with Rhodomicrobium vannielii DSM 162T (99 % sequence similarity). However, both strains exhibited only 46.1 % DNA–DNA hybridization with R. vannielii DSM 162T. Strains JA643T and JA755 shared >99 % 16S rRNA gene sequence similarity and were >85 % related on the basis of DNA–DNA hybridization; they are therefore considered to represent a novel species in the genus Rhodomicrobium , for which the name Rhodomicrobium udaipurense sp. nov. is proposed. The type strain is JA643T ( = KCTC 15219T = NBRC 109057T).