Rhodopseudomonas marina sp. nov., a New Marine Phototrophic Purple Bacterium

Four new isolates from different saline habitats are described as the new species Rhodopseudomonas marina. Cells are short, motile rods with intracytoplasmic membranes lying parallel to the cytoplasmic membrane. Bacteriochlorophyll a, and carotenoids of the normal spirilloxanthin series, are the photosynthetic pigments. The new species grows photo-trophically in the light under anaerobic conditions, but is also capable of growing in the dark under microaerophilic or anaerobic conditions, depending on the carbon source. Under phototrophic conditions a wide variety of organic carbon sources are used. Excellent growth with the sugar alcohols mannitol and sorbitol is the most significant aspect. Only rather low concentrations of sulfide are tolerated, although sulfide tolerance is enhanced in the presence of small amounts of yeast extract. Sulfide is not oxidized to sulfate; thiosulfate and elemental sulfur are the only detectable oxidation products. The different strains require 1-5% NaCl for optimal growth. The DNA base ratio is 61.5-63.8 mol% G + C. Rhodopseudomonas marina can be differentiated from all known Rhodospirillaceae species by its lipid and quinone composition.