The biochemistry of the Actinomycetales: studies on the cell wall of Streptomyces fradiae.

In order to gain some information on the comparative biochemistry of the Streptomyces, an investigation of the nature of the cell wall has been undertaken. There are only few data relating to the chemical composition of the actinomycetes. Thus, Avery and Blank (1954) found that representative species of Actinomyces, Nocardia, Streptomyces, and Micromonospora were all devoid of chitin and cellulose, which led them to the conclusion that the actinomycetales are related to bacteria rather than fungi. The present paper presents more decisive data which support this conclusion. Early in our studies, it was observed that cells of Streptomyces fradiae were lyzed by lysozyme. This provided some indirect evidence concerning the chemical nature of the cell wall since Epstein and Chain (1940) as well as Meyer and Hahnel (1946) were able to extract from cells of Micrococcus lysodeikticus a mucopolysaccharide which was depolymerized by lysozyme. This depolymerization was accompanied by the liberation of hexosamine and other reducing sugars. Furthermore, Salton (1952a, b, 1953) has shown that purified cell walls of various susceptible bacteria can be lysed by lysozyme, and he has supplied chemical data which indicated that these cell walls were of a mucoid nature. It thus appears that lysozyme is a mucopolysaccharase, and that sensitivity to this enzyme constitutes indirect evidence for the presence of mucopolysaccharide. Sensitivity of a purified cell wall preparation of the vegetative mycelium of Streptomyces fradiae to lysozyme now has been demonstrated and is reported here with supporting chemical evidence for the mucoid nature of these cell walls.