SUBSTANCES PRODUCED BY YEASTS 185 



Gliotoxin is sparingly soluble in water and readily soluble in alcohol. 

 It is unstable, particularly in alkaline solutions, and is sensitive to 

 oxidation and to heating (961 ) j it is inactivated by heating for 10 min- 

 utes at 100° C. ( 17). Its potency was found to be destroyed by bubbling 

 oxygen for 5 minutes. 



Gliotoxin is toxic to Rhizoctonia hyphae in a dilution of i : 300,000, 

 which is about two-thirds of the toxicity of HgCL. The crystals, as well 

 as the crude material, were found to be toxic also to Trichoderma, but 

 the minimum lethal dose was about 40 times greater than that required 

 for Rhi-zoctonia. Its antibacterial properties are brought out later. 



Other Substances. Several other antibacterial substances have been 

 isolated from fungi, but have not been adequately studied either chemi- 

 cally or biologically. It is sufficient to mention the following: 



Puberulic acid, CgHsOe, a colorless crystalline dibasic acid, with an 

 m.p. of 316-318°, and puberulonic acid, C8H4O6, a bright-yellow acid 

 with an m.p. of 298° C, produced (38, 58, 66$) by P. fuberulum. The 

 first is a quinol and the second is quinonoid. They have little activity 

 against gram-negative bacteria and some activity against gram-positive 

 types. 



Penicidin was isolated (26) from a species of Penkillium. It is soluble 

 in ether, alcohol, chloroform, and dilute acids, but not in petrol ether. 

 It is destroyed by bases, and is adsorbed on active charcoal. It was found 

 to be active against E. tyfhosa. 



Chaetomin is produced by a species of Chaetommm {Ch. cochliodes) 

 grown in complex organic media. It is active largely against gram-posi- 

 tive bacteria (930). 



Kojic acid (Figure 16), produced by A. oryzae, apparently also pos- 

 sesses some antibacterial properties, more against gram-negative than 

 gram-positive bacteria (282). 



SUBSTANCES PRODUCED BY YEASTS 



According to Fernbach (253), certain yeasts produce volatile sub- 

 stances which are toxic not only to other yeasts but also to bacteria. Rose 

 yeasts {Torula suganii), either fresh or heated to 120 to 130° C, were 

 found (654) to contain a substance which has an antagonistic action 



