116 ACTINOMYCETES AS ANTAGONISTS 



any substance into the medium, the presence of the growing antagonist 

 was essential in order to bring about an inhibition of bacterial develop- 

 ment. On the basis of their sensitivity to the antibiotic substance of 

 actinomycetes, mycobacteria could be differentiated from nonspore- 

 forming, especially nodule-forming, bacteria. The production of the 

 antibiotic substance was highest in synthetic media and was rather weak 

 or even totally absent in media that contained proteins. The substance 

 was filterable and was able to resist the effect of radiation. 



It was further reported (671) that the antagonistic effects of actino- 

 mycetes were manifested not only in artificial media but also in soil, the 

 interrelations here being much more complex. Some of the strains that 

 produced antagonistic effects in artificial nutrient media were ineffec- 

 tive under soil conditions. The antagonistic action was more intense 

 in light podzol soils and was greatly reduced in heavy or chernozem 

 soils. One of the factors that resulted in a decrease in the antagonistic 

 properties of actinomycetes in the heavy soils was apparently the high 

 content of organic matter. By adding peptone to a light soil, the antago- 

 nistic action of the actinomycetes was greatly weakened. When actino- 

 mycetes were allowed to multiply in the soil before inoculation with 

 B. mycoidesy the antagonistic effect was highly pronounced even in the 

 presence of high concentrations of peptone. 



An attempt to isolate an antibiotic substance from some of the soil 

 actinomycetes was made by Kriss {S'i^)- On the basis of its properties 

 he was led to conclude that this substance could be classified definitely 

 with lysozyme. It was insoluble in ether, petroleum ether, benzol, and 

 chloroform, and was resistant to the effects of light, air, and high tem- 

 peratures. The optimum reaction for the production of this substance by 

 Streftomyces violaceus was found to be ^H 7.1 to 7.8, the activity not 

 being increased by selective cultivation. On the basis of its properties, 

 this substance could hardly be classified with egg-white lysozyme. It 

 must be concluded also that the differences in the antibiotic properties 

 of the various antagonistic actinomycetes isolated by the Russian investi- 

 gators definitely point to the fact that more than one antibiotic substance 

 was involved. 



In a more recent survey (958) of the distribution of antagonistic ac- 

 tinomycetes in soils and in composts, it was found that of 244 cultures 



