Ultrastructural studies of Sphaerophoms varius and the infective process of an associated bacteriophage

Abstract

The anaerobe Sphaerophoms varius was found by electron microscopy to be a typical Gram-negative organism in its ultrastructural anatomy. However, the following additional characteristic features were observed; small (25–100 nm), membrane-bound dark bodies, groups of thin, rod-shaped inclusions, and pointed poles. An associated bacteriophage was found to consist of an octahedron with a very short tail like coliphage T3. It proved to be temperate and was released in large quantities by the mitomycin C induction of a lysogenized clone of the host organism. Induction also produced rods (identified with those in sections), and empty capsids believed to be of viral origin. Electron microscopy showed that the virulent infective process caused structural changes in the nucleoplasm before phage assembly and release; this was achieved by a single break in the cell envelope. It was concluded that S. varius was able to support at least two different plasmids, a bacteriophage and a probable bacteriocin.