Rhodopseudomonas rhenobacensis sp. nov., a new nitrate-reducing purple non-sulfur bacterium.

During the course of isolating and identifying purple non-sulfur bacteria, one nitrate-reducing strain was isolated which did not fit the description of any other purple non-sulfur bacterium known to date. The isolate had rod-shaped cells that contained lamellar intracytoplasmic membranes and produced red cultures. Absorption maxima of photosynthetically grown cell homogenates were at 376, 471, 503, 540, 591, 805 and 878 nm. The new isolate grew anaerobically in the light or aerobically in the dark. Various organic compounds served as carbon sources and electron donors. The predominant quinone was ubiquinone 10, the predominant fatty acid was 18:1omega7c. The polar lipids comprised diphosphatidyl glycerol, phosphatidyl glycerol, phosphatidyl ethanolamine and phosphatidyl choline. Analysis of the 16S rDNA gene sequences revealed that the new isolate was closely related to Rhodopseudomonas palustris. A DNA-DNA- hybridization study differentiated the new isolate and Rhodopseudomonas palustris at the species level. Therefore, the name Rhodopseudomonas rhenobacensis sp. nov. is proposed for the new isolate.