212 



THE ACTINOMYCETES, Vol. I 



60 TO SO SO 100 no 130 



R. JAPONICUM 



Figure 82. Relative susceptibility of test organisms to antagonistic actinomj-cetes (E. coli = 100) 

 (Reproduced from: Landerkin, G. B. and Lochhead, A. G. Can. J. Res. 26C: 505, 1948). 



procedures, with numerous modifications, 

 have found extensive apphcations in the 

 study of the antagonistic properties of ac- 

 tinomycetes and have come to be known as 

 screening methods. 



In 1935, the first comprehensive survey 

 for the occurrence of antagonistic forms 

 among actinomycetes, largely soil inhabit- 

 ants, was begun in Russia. Similar surveys 

 of the occurrence of antibiotic-producing 

 microorganisms, especially actinomycetes, 

 were started in the United States in 1939. 

 These surveys influenced greatly the whole 

 subsequent history of antibiotics. 



General Surveys 



The first survey of the occurrence in soil 

 of antagonistic actinomycetes was made by 

 Nakhimovskaia. Out of 80 cultures of actino- 

 mycetes isolated and tested, 47 were able to 

 exert antagonistic effects, but only 27 pro- 

 duced active substances. (Jram-positive bac- 

 teria were inhibited, but not gram-negative 

 bacteria or fimgi. No relation was observed 

 between antagonism and formation of pig- 

 ments, manner of sporulation, or shape of 



spores. Since the capacity to produce anti- 

 bacterial substances was possessed by only 

 certain cultures, it was suggested that this 

 property could be utilized for the systemati- 

 zation of species of actinomycetes. It was 

 also suggested that various bacteria could 

 be differentiated on the basis of their sensi- 

 tivity to the actinomycetes. 



Krassilnikov and Koreniako found that 

 many species of actinomycetes, members of 

 the group now considered as the genus 

 Streptomijccs, but not of Nocardia, produce 

 substances that are strongly bac^tericidal 

 against nocardias, mycobacteria, micro- 

 cocci, and spore-forming bacteria, but not 

 against gram-negative bacteria, lender the 

 influence of these substances, the microbial 

 cells are either entirely lysed or are killed 

 without subsequent lysis. This chemical na- 

 ture of the active substance was believed to 

 be similar to that of lysozyme. 



Ki'iss is()lat(>d a chemical agent from cul- 

 tures of actinomycetes. The substance was 

 found to be insoluble^ in ether, petroleum 

 ether, benzol, and chloroform, and was re- 

 sistant to the effect of light, air, and high 



