Rapid Formation of Protoplasts of Streptomyces griseoflavus and Their Fine Structure

Abstract

Glycine, at a concentration of 5-10%, inhibited the growth of Streptomyces griseoflavus. The lysozyme sensitivities of the cell walls of the organisms cultured with and without glycine were the same. However, lysozyme caused 40% lysis of whole cells from cultures with glycine but had no effect on cells from cultures without glycine. The cell walls of organisms grown with and without glycine contained glucosamine, galactosamine, muramic acid, lysine, glutamic acid, glycine, alanine and DAP. Lysine and DAP were present in equimolar amounts. Very small amounts of asparagine, threonine and serine were found in both cell walls. Protoplasts were obtained in a high yield by treating cells from cultures containing glycine with 10mg/ml of lysozyme in 0.01M phosphate buffer (pH7.0) containing 0.1 MgSO₄ and 1M sucrose for 3 hr. The protoplasts were spherical and were surrounded by cytoplasmic membranes. The nucleoplasm appeared less dense with a clear network of nuclear fibers and mesosomes, abundant in whole cells, were scarcely seen. Rod-shaped forms without cell wall materials were sometimes observed under the electron microscope.