GROWTH 179 



matter which may derive from the sugar. The subtraction of 

 alcohol and CO 2 from the total sugar leaves 329 kg. to be accounted 

 for by "growth and by-products." Of this amount, 224 kg. are found 

 in the non-nitrogenous part of the yeast. The remaining 105 kg. 

 may have been at least partly used in cell construction, but it cannot 

 be proved. 



The observation that of the 1,575 kg. sugar used, at least 224 kg. = 

 14.2 % had been used as construction material, in addition to a simi- 

 lar quantity of nitrogenous matter, is of considerable interest, as not 

 nearly such large amounts have ever been found to be assimilated by 

 bacteria. The efficiency of energy utihzation must be quite high. 



According to Lindner and linger (1919), yeast will produce fat from 

 alcohol if plenty of oxygen is available. If the increase in non- 

 nitrogenous matter were largely fat, produced from alcohol, it is 

 evident that fairly large quantities of alcohol must be used because, 

 according to the simplest formula 



8C2H5OH -f- = C16H34O2 + 7H2O 



Alcohol Palmitic acid 



it takes about 3 kg. of alcohol to produce 2 kg. of fatty acid. 



Both authors give special nitrogen balances for their 

 experiments. That of Claassen is the following: 



Table 41. — Nitrogen Balance in Yeast Growth 

 Nitrogen in medium : 



3,000 kg. molasses with 1.67% N = 50.10 kg. N 

 525 kg. malt sprouts 1.70% N* = 8.93 kg. N 



59.03 kg. N 



Nitrogen in seed yeast : 



360 kg. yeast with 2.18% 7.85 kg. N 



4 , 400 kg. wort of seed yeast with 0.0682 % N 3 . 00 kg. N 



10.85 kg. N 

 Total N at start .^ 69 . 88 



1,875 kg. total yeast crop 1.95% N 36.56 kg. N 



77,000 kg. fermented wort 0.045% N 34.65 kg. N 



Total N at finish 71.21 71 . 21 



* Soluble nitrogen only. 



