NUTRITION OF YEASTS 71 



(NH 4 ) 2 + sucrose = 71.8 per cent increase 



" + dextrose = 113.0 " " 



Asparagin + sucrose = 103.7 " " " 



Aspartic acid + " 61.3 " " 



Leucine + " = 90.3 " " 



Tyrosine + " = 61.3 " " 



Glycine+ " = 25.8 " " 



With somatose (flesh albumose) there was a decrease of 9.7 per 

 cent which would seem to indicate that the albumoses must be fur- 

 ther decomposed. Peptone with sucrose gave an increase of 177 per 

 cent while peptone alone gave 152 per cent. 



Lindner and Wiist 1 find that urea can serve yeasts and molds as 

 sources of nitrogen but not for carbon. Bokorny 2 has measured the 

 increase in development of yeast when nitrogen is taken from urea, 

 by the dry weight. Considerable growth took place when the yeast 

 was grown in urine to which sugar had been added. The urea and 

 not the hippuric acid is said to be the source of the nitrogen. 



Hoffman 3 has shown that the addition of ammonium chloride to 

 bread dough saved 30 per cent of the yeast ordinarily used. Experi- 

 ments were carried out which showed that this nitrogen went to con- 

 struct yeast protein. Good arguments are presented which show 

 that this salt does not go for other purposes. Ehrlich 4 stated that 

 ammonium salts were readily changed into yeast protein. Delbrtick 

 and Classen 5 have used ammonium salts for cultivating yeast. Voltz 6 

 found that the composition of yeast grown on mineral salts was like 

 that grown with other sources of nitrogen. 



Kossowicz and Groller 7 have stated that the thiocyanates will 

 serve yeasts as source of nitrogen and sulfur but not carbon. 



1 Lindner, P., and Wiist, G. Assimilation of urea by yeasts and molds. 

 Wochenschr. Brau. 30, 477-9. Chem. Absts. 8 (1914), 727. 



2 Bokorny, Th. The increase in dry weight of yeast when urea is used as 

 the source of nitrogen. Biochem. Zeit. 82 (1917), 359-390; The culture of yeast 

 in the presence of air with the use of urea as source of nitrogen and with different 

 sources of carbon. The quotient of sugar assimilation. Biochem. Z. 83 (1917), 

 133-164. Chem. Absts. 12 (1918), 1203. 



3 Hoffman, C. H. The utilization of ammonium chloride by yeast. Jour. 

 Ind. Eng. Chem. 9 (1917) 148-151. 



4 Ehrlich. Biochem. Z. 18, 391-423. 



5 Delbriick. Classen. A new method for increasing the production of yeast. 

 Z. Ver. Deut. Ing. 59 (1915), 844. 



6 Voltz. Utilization of the animal organism of yeast produced from sucrose 

 and nutritive mineral salts. Z. Spiritusind. 38 (1915) 235-6. 



7 Kossowicz, A. and Groller, L. Thiocyanates as a source of carbon, nitrogen 

 and sulfur for molds, yeasts and bacteria. Zeit. Garungsphysiologie, 2, 59-65. 

 Chem. Absts. 7 (1913), 808. 



