SUBCELLULAR PARTICULATE SYSTEMS AND THE PHOTOCHEMICAL APPARATUS OF RHODOSPIRILLUM RUBRUM

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Abstract
Osmotic lysis of altered fragile cell-forms (protoplasts) of this gram-negative photosynthetic bacterium does not release significant amounts of free chromatophores, but results inthe formation of pigmented membranous structures ("ghosts") capable of photophosphorylating adenosine diphosphate. A 2d type of photochemically active form, closely resembling the "empty ghosts" of certain gram-positive bacteria, can be prepared by sequential action of lysozyme and the polypeptide antibiotic polymixin B on resting cells. Both types of preparations, in contrast with free chromatophores, are readily sedimented at low centrifugal force. On the basis of the current findings and other observations from the literature, it is concluded that in vivo the photochemical apparatus of the photosynthetic bacteria is associated with the cytoplasmic membrane and/or membranous extensions in the cytoplasm of the cell.