CHAPTER 7 



FUNGI AS ANTAGONISTS 



The antagonistic interrelationships in which fungi are involved com- 

 prise the following reactions: (a) the antibacterial activities of fungi j 

 (b) the antagonistic effects of fungi upon fungi; (c) the effects of bac- 

 teria and actinomycetes upon fungi j (d) the action of fungi upon in- 

 sects and other animal forms. From the point of view of practical utiliza- 

 tion, two aspects deserve special consideration: (a) the utilization of 

 fungi for combating human and animal diseases; (b) the antagonistic 

 interrelationships of fungi with other organisms, since fungi comprise 

 the most important group of microorganisms that cause plant diseases. 



ANTIBACTERIAL EFFECTS OF FUNGI 



Duchesne (207) was the first to report, in 1897, that certain green 

 Penicillia are capable of repressing the growth of various bacteria or of 

 bringing about their attenuation. Vaudremer (912) demonstrated in 

 19 13 that the presence oi A.fumigatus results in the attenuation of the 

 cells of M. tuberculosis. 



Since these early studies a number of fungi have been found to pos- 

 sess antibacterial properties; this phenomenon has sometimes been 

 spoken of as mycophagy (914). Several fungi have been studied in de- 

 tail, and in some cases one or more antibiotic substances have been iso- 

 lated (Figure 12). The property of inhibiting the growth of bacteria is 

 not characteristic of any one genus or even species, but of certain strains 

 within a given species. Some organisms produce more than one active 

 substance. Two genera, Penicillium and Aspergillus, have been found 

 to comprise a large number of antagonistic forms. Several other genera 

 are also known to contain organisms that possess antibacterial proper- 

 ties; very few of these, however, were ever found among the Phycomy- 

 cetes and Basidiomycetes. The known fungi capable of producing anti- 

 biotic substances may be divided (934) into the following ten groups: 



Aspergillus clavatus A . fumigatus 



A. jiavus-ory'z.ae Penicilliwrn cyclofium-clavijorme 



