80 BIOCHEMISTRY OF FUNGI 



the mvcelia. According to Pearson and Raper (1927), the fresh 

 mycelium of Aspergillus iiiger contains 2.4% fat and that of 

 Rhizopus nigricans 5%. These fats in Penicillium aurantio-brun- 

 neinn were studied by Strong and Peterson (1934) and were 

 found to resemble butterfat. The analyses showed them to con- 

 tain 40.2% oleic acid, 31.2% lineolic acid, 8.6% palmitic acid, and 

 5.3% stearic acid; the remainder consisted of 9.1% glycerol, 1.9% 

 ergosterol, and a non-fatty residue of 4.5%. Their analysis of 

 the fats of Aspergillus sydoixii showed 8.8% palmitic acid, 11% 

 stearic acid, 29.6% oleic acid, 16.3% lineolic acid, and a small per- 

 centage of higher unsaturated acids. Analysis of the fats of 

 Penicillium javanicum by Ward and Jamieson (1934) revealed 

 them to consist of 69.5% palmitic acid, 28% stearic acid, and 2.5% 

 7;-tetracosic acid. Nord and A lull (1945) indicated that Fusarium 

 gramineum forms fats similar to those produced by yeasts. 



The factors that influence the amount of fat produced have 

 been investigated by Lockwood et al. (1934) and Ward et al. 

 (1934, 1935) in a goodly number of species of molds. They se- 

 cured best production with Penicillium javanicum when it was 

 grown on a medium containing 40° ' glucose. Sucrose, xylose, 

 and glycerol also served well as carbon sources. These workers 

 found that the mycelium contained up to 41.5% fat in old cul- 

 tures. The studies of Prill, Wenck, and Peterson (1935), using 

 Aspergillus fischeri, showed increased fat production with higher 

 pH within the range 2.0 to 8.0, along with greater concentration 

 of glucose. 



Even though the syntheses are not understood, the procedures 

 are now so well known that they could be utilized industrially 

 if a supply of animal fats could not be procured. In fact, one of 

 the Endomycetales, Endomyces vernalis, has been used for some 

 time in the commercial production of fats. 



Various hypotheses, briefly considered by Smedley-AIcLean 

 (1936), have been proposed to explain the mechanisms involved 

 in the transformation of a carbohydrate into a fatty acid. Con- 

 densation of three hexose molecules to give the stem of stearic 

 acid or of two pentose molecules and one hexose molecule to give 

 palmitic acid has been suggested. In support of this hypothesis 

 attention may be directed to the fact that in many naturally 

 occurring fatty acids the number of carbon atoms is a multiple 

 of six. 



