GENERAL PHENOMENA OF NUTRITION 55 



Amato l demonstrated the presence of lipoids in Saccharomyces 

 cerevisiae by chemical and microchemical methods. He treated yeasts 

 in fixed preparations with osmic acid, finding that most of the granules 

 became brown in color. By their reaction to fat solvents, the majority 

 of these granules were regarded as belonging to Bernard and Bigart's 

 labile fats. Amato thinks that most of the lipoids in yeast are 

 lecithins. Extraction of both the washed and dried yeast with 

 ether gave a residue which, after combustion, and extraction with 

 sodium carbonate, yielded the characteristic phosphoric acid pre- 

 cipitate with ammonium molybdate. Bokorny 2 has reviewed this 

 subject from the point of using this yeast fat commercially. The 

 need for these fats was especially emphasized in Germany during 

 the war on account of the successful blockade of German ports by 

 the Allies. Bokorny stated that much study was required before the 

 yeast fat could be put on a commercial basis. Neville 3 studied yeast 

 fats and found that the principal fatty -acids had the empirical formula 

 Ci5H 3 oO 2 , but that arachidic acid, C 2 oH 40 O 2 , melting at 77 C., was 

 not very abundant. Unsaturated acids could not be separated in the 

 pure state. Oxidation with KMn04 yielded the corresponding di- 

 and tetrahydroxy acids which indicated the presence of CieHaoO^, 

 Ci 8 H 3 4O 2 and C 18 H 32 O 2 in the fat. Cholesterol melting at 145-147 C. 

 was obtained. Bokorny 4 has made further observations on yeast 

 fat and found a greater accumulation when the source of nitrogen 

 was peptone than when amino acids (glutamic and aspartic) were 

 used. Dilute urine to which sugar had been added represented the 

 cheapest source of nitrogen. 



Albuminoids : A material approaching egg-albumin in characteris- 

 tics has been found in yeasts. According to Trommsdorf and Meisen- 

 heimer 6 the cake obtained by the compression of the yeasts, in the 

 preparation of yeast juice, which contains zymase, is colored black 

 by Grams solution and safranin while the juice takes a red tint with 

 the same reagents. There must be present, then, in yeast a soluble 

 albumin which may be colored red and an insoluble albumin which 

 takes a black color according to this procedure. 



There has been proven in yeasts, an albuminoid substance soluble 

 in warm alcohol, which must be a peptone produced by the action of 



1 Amato, A. The lipoids of blastomycetes. Cent. Bakt. Abt. Ill, 42, (1915) 

 689-98. 



2 Bokorny, Th. Yeast fat. Allgem. Brau-Hopfen Ztg. 55, (1915) 1803-5. 



3 Neville, H. A. D. The fat of yeast. Biochem. Jour. 7, 341-348. 



4 Bokorny, Th. Accumulation of fat in plant cells, especially in yeasts. Arch, 

 physiol. 305-349, 1915; Chemical Abstracts, II, (1917) 260. 



6 Meisenheimer, J. Neue Versuche mit Hefepressafs. Zeit. physiol. Chemie, 

 37, 1904. 



