Rhodoferax fermentans gen. nov., sp. nov., a phototrophic purple nonsulfur bacterium previously referred to as the ?Rhodocyclus gelatinosus-like? group

Abstract

Strains of the phototrophic bacteria previously referred to as the “rhodocyclus gelatinosus-like (RGL)” group were taxonomically studied in comparison with Rhodocyclus species. Cells of the RGL strains were curved rods and motile by means of polar flagella. They contained bacteriochlorophyll a and carotenoids of the spheroidene series. The intracytoplasmic membrane system was absent. Photoorganotropho with various organic compounds as carbon sources was the preferred mode of growth. Aerobic growth at full atmospheric oxygen tension and fermentative growth under anaerobic-dark conditions were also possible. The major cellular fatty acids were palmitoleic acid and palmitic acid, and 3-hydroxylated fatty acids with octanoic acid predominating were also found. Both ubiquinone-8 and rhodoquinone-8 occurred as major quinones. The mol% guanine plus cytosine of the DNAs varied between 59.8 and 60.3. DNA-DNA hybridization studies showed that the RGL strains were highly related to each other but exhibited low levels of the homology to Rhodocyclus species. These data allow the establishment of the RGL group as a new taxon of the purple nonsulfur bacteria, for which the name Rhodoferax fermentans gen. nov., sp. nov. is proposed.