STEROLS AND VITAMINS SI 



Another hypothesis is that acetaldehyde is produced from lactic 

 acid as an intermediate substance and that by its repeated conden- 

 sation the series of fatty acids from butyric upward is produced. 

 The culturing of fungi on solutions of acetaldehydes has not 

 strongly supported this hypothesis. 



Another hypothesis, which is looked upon with favor but has 

 not been elucidated, is that the hexose is fermented to pyruvic 

 acid, from which the fatty acid is formed. 



STEROLS AND VITAMINS 



Within the past few years an appreciation has been developing 

 that sterols and vitamins occur in fungi. This recognition has 

 come in part from the therapeutic use of yeast to correct dietary 

 deficiencies. The dietetic value of yeast becomes all the more 

 remarkable when it is remembered that the yeast plant, cultured 

 on hexose solution containing ammonium chloride together with 

 a few drops of wort in which yeasts have previously been grown, 

 is able to synthesize not only a goodly complement of vitamins 

 but also all the amino acids. All these syntheses by a simple 

 plant! To date the function of sterols (ergosterol, CosH^O.oo, 

 is the precursor of vitamin D) and vitamins in fungi remains 

 largely unknown. The studies have centered largely on the oc- 

 currence of these substances and on their employment in animal 

 feeding. Evidently they are of wide occurrence among fungi. 

 The factors which condition their formation were studied by 

 Birkinshaw, Callow, and Fischmann (1931). In 1929 Heiduschka 

 and Lindner [Birkinshaw (1937)] determined the ergosterol con- 

 tent of Dematium pullirtans to be 0.3% of the dry weight; of 

 Penicillium glaiicum, 0.75%; and of Aspergillus oryzae, 0.46%. 

 Bernhauer and Potzelt (1935) found a variation in sterol content 

 of 0.23 to 1.16% among 16 strains of A. niger. 



Preuss et al. (1931, 1932, 1932a) studied the sterol content of 30 

 species of Aspergillus, 20 of Penicillium, and 15 of other species 

 of fungi when grown on a synthetic medium containing 4° 7 glu- 

 cose. The difference in sterol content among species is shown by 

 the occurrence of 0.98% in Aspergillus oryzae, 0.4% in A. niger, 

 0.35% in Penicillium expansum, and 0.16% in P. janthivellum. 

 They found that different strains of the same species vary in 



