Cellular organization of the halophilic, phototrophic bacterium strain WS 68

The obligatory halophilic, phototrophic bacterium, strain WS 68, grows under anaerobic conditions in the light in a mineral medium with acetate as carbon source and 6 to 20% sodium chloride, or in the same medium semiaerobically in the dark. The cells are vibrio- or spiral-shaped and show a bipolar polytrichous flagellation. The absorption spectrum of membranes, isolated from phototrophically grown cells, shows absorption maxima at 375, 490, 520, 555, 590, 800, 840-845 and 870-875 nm indicating the presence of bacteriochlorophyll a and carotenoids as pigments of the photosynthetic apparatus. The cell surface is covered with a layer of regular arranged particles (center to center distance approximately 10.5 nm). A murein (peptidoglycan) sacculus has not been detected in ultrathin sections, freeze fracture preparations and cells extracted with hot dodecyl sulfate. The intracytoplasmic membranes lie parallel to the cell envelope. The polypeptide patterns of isolated membranes and of the envelope fraction have been demonstrated. The results are discussed in the light of taxonomy and cell organization.