Bacteriolytic Enzymes from Streptomycetes A review

A study of the bacteriolytic properties of streptomycetes has progressively uncovered the production by these microorganisms of a large number of different enzymes acting upon various bacterial constituents, especially on some of them located in the cell wall Although the mechanism of the bacteriolysis is far from being completely elucidated at present, it can, however, be stated that, in two instances at least, it can be regarded as an osmotic explosion following upon the destruction of the structure responsible for the rigidity of the cell wall. Leaving aside the often quoted but rather incidental observation of Gasperini (1890), it may be stated that the ability of Streptomyces spp. to lyse the bacterial cells of diflerent species, either previously killed or alive, was independently discovered by Lieske (1921) and by Gratia and Dath (1924). The latter demonstrated that the lytic activity could be recovered in the cellfree filtrate from a suitable actinomycete culture. Similar reports were published during the following years (Rosenthal, 1925; Dath, 1927; Borodulina, 1935; Gratia and Alexander, 1931) and, later on, b y analogy with the word "penicillin," as originally introduced by Fleming (1929), we proposed to designate such bacteriolyfic cell-free fluids as actinomycetin (Welsch, 1937 c). The actinomycetin type of lytic activity, which is quite widespread among Actinomycetes (Welsch, 1942, 1947 c; Bergamini, Ghuysen, and Welsch, 1954), can be described as follows : (a) The active actinomycete, when planted in a suspension of properly killed bacteria belonging to any one of a large number of species tested, will grow and dissolve the bacterial bodies. (b) The same result obtains when the actinomycete is planted in a suspension of living bacteria belonging to a wide variety of Gram-positive species. (c) The cell-free fluid, obtained after centrifugation or filtration of a culture of the actinomycete, in short, actinomycetin, shows the bacteriolytic activities described under (a) and (b), although its effects upon living bacteria are often somewhat more restricted and may be rather irregular. A microorganism, which we isolated in 1936 (Welsch, 1936) and which