THE STRUCTURE OF PHOTOSYNTHETIC BACTERIA

Abstract

Ultrathin sections of photosynthetic bacteria revealed discrete vesicles, the chromatophores, when examined by electron microscopy. The maximum size of the chromatophores of each species as measured along their long axes is as follows: Rhodospirillum rubrum, 1000 A; Rhodopseudomonas sphaeroides, 800 A; Chromatium sp. Strain D, 400 A; Chlorobium limicola, 300 A. The chromatophore membrane of R. rubrum is composed of particles approximately 70 A in diameter. Dark-grown cells of R. rubrum lack chromatophores; the formation of chromatophores is light dependent. The chromatophores of C. limicola are more dense than those of the other species studied. Chromatophores are packed throughout the cytoplasm of photosynthetically active cells.