title: Growth characteristics and ultrastructure of protoplast type L-forms from streptomycetes.
abstract: L-form colonies from S. hygroscopicus, S. griseus and S. levoris were isolated after incubation of lysozyme protoplasts on an osmotically stabilized complex agar medium. Unstable and stable L-forms grow on solid and in liquid media. L-form colonies are 5-10 times smaller than normal colonies and show a typical morphology for each species. In ultrathin sections L-form cells are characterized by nucleoid areas with typical core-like structures, by a ribosome-rich cytoplasm with different inclusion bodies, and by a cytoplasmic membrane. Because there are no cell wall structures L-forms of the three Streptomyces species belong to the protoplast type. Analysis of cell size and cell shape shows a variation in diameter and a cell propagation by regular and irregular division- and budding-like processes. Many L-form cells contain more than two chromosomes. The results are discussed with regard to the cellular organisation of streptomycetes and the nature of the stable L-form.
mesh_terms: D002462:Cell Membrane / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D002479:Inclusion Bodies / Q000648:ultrastructure; D007740:L Forms / Q000254:growth & development* / Q000648:ultrastructure; D008854:Microscopy, Electron; D013302:Streptomyces / Q000254:growth & development* / Q000648:ultrastructure; D013305:Streptomyces griseus / Q000254:growth & development / Q000648:ultrastructure