Waksman — 108 — Actinomycetes 



parasite, as a result of the faculty that the actinomycetes possess of di- 

 gesting the membrane of these lower fungi. Greig-Smith first demon- 

 strated the ability of actinomycetes to produce antibiotic agents. 



LiESKE, who tested a large number of actinomycetes for their anti- 

 bacterial action, established that this process is selective in nature, af- 

 fecting only certain bacteria, such as S. anreiis and that different actino- 

 mycetes vary greatly in this respect. Lieske believed, however, that the 

 antagonistic effect of actinomycetes may be due to a specific bacteriolytic 

 enzyme, namely: "Ein bestimmtes bakterienlosendes Enzym konnte aus 

 den Kulturen nicht isoliert werden; dass ein solches in Frage kommt, 

 ist aber bei der grossen biologischen Bedeutung, welche die Vernich- 

 tung von fremden Mikroorganismen in der Natur fiir die Strahlenpilze 

 besitzt, nicht ausgeschlossen." 



Rosenthal (369) introduced, in 1925, suitable methods for meas- 

 uring bacteriostatic and bacteriolytic activities of actinomycetes. He 

 isolated from the dust an actinomyces culture which he designated the 

 true biological antagonist of the diphtheria organism. The surface of 

 an agar plate was covered with an emulsion of the test bacteria, and the 

 actinomyces culture was inoculated into several spots on the plate. 

 After 2 days the actinomyces colonies were surrounded by large trans- 

 parent zones, whereas the rest of the plate was covered with the growth 

 of the diphtheria organism. In another experiment, the agar was 

 mixed with a heavy emulsion of the diphtheria organism, which had 

 previously been killed by heat, and the mixture poured into the plates. 

 After solidification of the agar, the actinomyces culture was inoculated 

 into several spots on the plates. The actinomyces colonies gradually 

 became surrounded by clear zones, thus establishing the fact that the 

 organism produced a lytic substance which diffused through the agar 

 and dissolved the dead diphtheria cells. 



Gratia (155) made a careful study of actinomycetes as agents pro- 

 ducing materials (mycophages) that are capable of bringing about the 

 lysis of bacterial cells. These effects were largely exerted upon dead 

 bacteria, although living cells were later found to be affected also (154). 

 The antibiotic substance produced by one of the organisms (A. alhiis') 

 at first considered to be of the nature of an endo- and exo-bacteriolysin 

 (499). It was later designated by Welsch as actinomycetin, as pointed 

 out previously. The lysis of living bacteria was considered to occur in 

 two stages: first, bactericidal effect of the substance upon the living bac- 

 teria; second, bacteriolytic action upon the dead bacteria, this process be- 

 ing helped by cell autolysis (502, 503). 



The first detailed survey of the distribution of antagonistic actino- 

 mycetes in nature was made by Nakhimovskaia (316). Of 80 cul- 

 tures isolated from a variety of soils, 47 possessed antagonistic properties; 

 however, only 27 of these were found capable of liberating antibiotic 

 substances into the medium (Table 20). These actinomycetes pos- 

 sessed the property of inhibiting the growth of gram-positive bacteria 



