Chapter VII — 109 — Antagonistic Properties 



but not of gram-negative bacteria or of fungi. These antibacterial 

 properties were manifested, not only in artificial culture media, but also 

 in the soil. Some of the cultures that were antagonistic to bacteria in 

 nutrient media were ineffective, however, in the soil. The effects were 

 more intense in hght, or podzol, soils and much weaker in heavy, or 

 chernozem, soils. The high content of organic matter in the latter 

 types of soil was believed to be one of the factors that resulted in a de- 

 crease in the antagonistic activities of these organisms. When the 

 actinomycetes were allowed to multiply in the soil before inoculation 

 with bacteria, the antagonistic effect was very pronounced even in the 

 presence of a high concentration of organic materials. 



According to Borodulina (43), actinomycetes are able to antag- 

 onize various spore-forming bacteria and bring about the lysis of the 

 living cells. He found that a thermostable substance was produced on 



Table 20: Occurrence of antagonistic actinomycetes in different soils (316): — 



agar media. The activity of this substance was greatly reduced at an 

 alkaline reaction but was favored by an acid reaction. When B. 

 mycoides and an antagonist were inoculated simultaneously into peptone 

 media, no inhibitive effect was produced because the bacterium changed 

 the reaction of the medium to alkaline, thereby making conditions un- 

 favorable for production of the antibiotic substance by the antagonist. 

 When the antagonist was allowed to develop in the medium before the 

 bacterium was inoculated, a strong antibiotic effect became evident in 

 elongation of the vegetative cells of B. mycoides. This was due to a 

 delay in fission and was accompanied by the suppression of spore forma- 

 tion. 



Krassilnikov and Koreniako (237) also reported that many species 

 of actinomycetes, notably members of the genus Streftomyces, but not 

 of Nocardia, produce a substance that is strongly bacteiicidal to a vari- 

 ety of organisms. This substance was said to be particularly active 

 against nocardias, mycobacteria, and micrococci. It was less active upon 

 spore-forming bacteria and had no action at all on non-spore-forming bac- 



