46 



THE COMPOSITION OF FUNGUS CELLS 



and co-workers (110, 160, 188); some of the known environmental 

 factors determining fat content are discussed in Chapter 6. High fat 

 values — 20 per cent or more of the dry weight — are found among 

 species and strains of Aspergillus, Endomyces, Fusarium, Mucor, 

 Oospora, Penicillium, and Torula (10, 48, 110, 131, 132, 160, 161, 185, 

 188), and in individual species of other genera (147, 157, 188). The 

 highest fat contents reported are about 50 per cent of the dry weight 

 (10, 110). Conidia of common saprophytic fungi do not have unusually 

 high fat contents, but the sclerotia of Claviceps purpurea contain 43 

 per cent lipids (154) and uredospores of Puccinia graminis tritici are 

 high in fat (Chapter 12). 



Some variation in apparent lipid content arises from the use of 

 different methods of extraction; these are discussed with reference to 

 the fungi by Peck (122) and by Bernhauer and others (11). 



In Table 5 are collected a few partial analyses of fungal lipids. The 



Table 5. Lipids of Fungi 



Organism 



Aspergillus niger (13) 95.1 



Aspergillus sydowi (169) 114.4 



Blastomyces dcrmatitidis 



(123) 106.1 



Fusarium graminearum 



(108) 84.7 



Penicillium javanicum 



(184) 84.0 



Phycomyces blakesleeanus 



(9)" 



* As per cent of total lipid. 

 f Ergosterol. 



Iodine Acid 



Number Number 



71.2 

 43.4 



45.3 



10.6 



Phospha- 

 tides* 



Present 



24.3 



Unsapon- 



ifiable 

 Matter* Sterols* 



9.9 



12.0 

 8.2 



8.0 



2.1 



2.0 



5.3 



1.4f 

 5.4 



4.0f 



most striking feature is the usually very high proportion of free fatty 

 acids; up to 88 per cent of the readily extractible lipids may be free 

 acids (138). However, it should be noted that the content of free acid 

 is markedly affected by cultural conditions. In Penicillium javanicum 

 the acid number rises from 10.6 to 50.7 as the glucose level of the 

 medium is increased from 20 to 40 per cent (185). In general, any 

 factor which increases fat formation also increases the relative amount 

 of free fatty acids (138). It should also be noted that Aspergillus 

 nidulans lipids are very low in free acid (161), as are sclerotia of Clavi- 

 ceps purpurea (197). It seems possible that lipase action during 



