134 FUNGI AS ANTAGONISTS 



Asfergillus davatus Growp 



This comprises a number of strains that produce highly active anti- 

 biotic substances. By treating the culture filtrate with charcoal and 

 eluting the active substance with ether, Wiesner ( 982 ) obtained a prepa- 

 ration having a bactericidal potency in dilutions of i : 100,000. This ac- 

 tivity was not inhibited by serum, pus, or urine j strains of bacteria that 

 proved to be resistant to sulfonamides or mandelic acid were inhibited 

 by this material. 



The active substance was designated (935) as clavacin. A detailed 

 study was made of its production by a variety of strains of A. dava- 

 tus. The substance was found to be active against E. coli and other 

 gram-negative bacteria, as well as against gram-positive bacteria. 

 It is distinct, in this respect, from fumigacin. Whereas the latter acts 

 much more readily upon B. mycoldes than B. subtilisy clavacin shows 

 the opposite effect — greater activity against B. subtilis than against B. 

 mycoldes. Clavacin possesses a high bactericidal action, as compared 

 with other antibiotic substances. It has been suggested (942) that the 

 marked differences in the physiology of the different strains of A. da- 

 vatus explain the differences in the production of clavacin by different 

 strains. Those that change the reaction of the medium to alkaline, for 

 instance, tend to inactivate the clavacin (Table 27). 



Since clavacin is produced by several fungi, this substance has re- 

 ceived a number of designations, including patulin produced by Pen'i- 

 cillium fatulum (713), claviformin by P. davijorme (114, 115), and 

 clavatin (47). It is also produced by strains of P. exfansuniy A. gigan- 

 teus, GymnoascuSy and other fungi (470). 



Trichoderma and GUodadium Grouf 



Certain strains of fungi of the genera Trichoderma and GUodadium 

 were found to exert a marked antagonistic action against various fungi 

 and bacteria. An antibiotic substance designated as gliotoxin was iso- 

 lated and found (962) to be highly bactericidal. In order to produce 

 this substance, the fungus is grown in a submerged condition in shake- 

 cultures. An abundant supply of oxygen and a high acidity {f¥L 5.0 or 

 lower) are essential. Ammonium salts as nitrogen sources give better 



