Structure of Bacterial L Forms and Their Parent Bacteria

Abstract

Weibull, Claes (Rocky Mountain Laboratory, Hamilton, Mont.). Structure of bacterial L forms and their parent bacteria. J. Bacteriol. 90: 1467–1480. 1965.—Light and electron microscopic studies were done on normal cells and L forms of Proteus mirabilis, Staphylococcus aureus , and Corynebacterium sp. grown in liquid media. Under the prevailing growth conditions, the L forms studied were morphologically indistinguishable from one another. They appeared as approximately spherical elements occurring singly or more often connected with each other by thinner portions of cell material. In sections of large L forms, the following structures were seen: a peripheral, triple-layered (“unit”) membrane, a granular cytoplasm, nuclear regions, and vacuoles limited by membranes. Small bodies often were present inside the vacuoles. These bodies also contained a peripheral membrane and a granular cytoplasm but usually no nuclear regions. The normal bacteria from which the L forms were derived differed markedly in structure from one another, especially in the surface layers of the cells.