Thiocapsa floridana; a cytological, physical and chemical characterization. I. Cytology of whole cells and isolated chromatophore membranes

The ultrastructure of the purple sulfur photosynthetic bacterium Thiocapsa floridana was examined by chemical fixation and freeze-etching. In addition, we describe two isolation and purification procedures for the chromatophore membranes of T. floridana. During freeze-etching membranes are split along a weak interior zone, resulting in two asymmetric membrane faces. Freeze-etch studies of both whole cells and of isolated membranes, in conjunction with the solubilization and reconstituting of isolated chromatophores, support a subunit membrane model in which protein complexes extend through the entire membrane.