ELECTRON MICROSCOPY OF CYTOPLASMIC STRUCTURES IN FACULTATIVE AND ANAEROBIC ACTINOMYCES.

Overman, John R. (Duke University Medical Center, Durham, N.C.) and Leo Pine. Electron microscopy of cytoplasmic structures in facultative and anaerobic Actinomyces. J. Bacteriol. 86:656-665. 1963.-Electron microscopy of cytoplasmic complexes and the cytoplasmic fine structure of Actinomyces bovis, A. israelii, A. naeslundii, and A. propionicus demonstrated marked differences among these four species. Also included in the present study was Lactobacillus bifidus, an organism closely related to the Actinomyces species. A relatively small and compact cytoplasmic membrane complex of A. propionicus was unique in its morphology. Membrane structures of A. naeslundii and A. israelii were relatively large and consisted of coils of various sizes of the cytoplasmic membrane. No membrane complexes were found in L. bifidus or A. bovis. Measurements of cell-wall thickness indicated a significant difference between A. bovis and A. israelii. On the basis of general morphology, cell-wall thickness, and cytoplasmic membrane complexes, A. bovis and A. israelii appear to be distinct species. The relation of the fine structure complexity to phylogenetic position of these organisms is considered.