80 PHYSIOLOGY OF YEASTS 



Lindner, 1 using Saccharomyces membranaefaciens, which assimilates 

 ethyl alcohol in the absence of other sources of carbon, could not find 

 an assimilation of methyl alcohol. 



Stockhausen 2 inoculated a mineral nutrient solution containing 

 (NH 4 ) 2 S0 4 as the source of nitrogen and 4 per cent of alcohol as the 

 source of carbon. Excellent yeast growth was secured in a few days. 

 This author argues that alcohol, in this case, was a food from which 

 plasma, cell membrane and fat could be built. The same fact was 

 established by Lindner and Czier. 3 



Rubner 4 believes that other than physical conditions control 

 assimilation and nourishment of yeasts since they take what sugar is 

 needed irrespective of its concentration. Rubner found that live 

 yeast, as well as yeast killed with toluene, quickly took up sugar 

 from a solution without fermentation, while yeast heated to 100 C. 

 did not. This author regards the yeasts as organisms possessing great 

 energy transformations per unit mass. Lindner 5 found that growth 

 took place at the expense of atmospheric nitrogen. Ethyl alcohol 

 and free ammonia were used to build protoplasm. Saccharomyces 

 acetethylicus assimilated nitrogen from nitrates. Urea provided assimi- 

 lated nitrogen particularly if maltose was present. Maltose was found 

 to be the best source of carbon. Melibiose and raffinose are readily 

 assimilated by yeasts even by some which do not ferment them. 



Respiration 



We have seen that yeasts placed in contact with air, act like 

 ordinary plants without causing alcoholic fermentation. Like all 

 living matter, they respire; they take in oxygen and liberate carbon 

 dioxide. The investigations of Schutzemberger, Grehant and Quin- 

 quand 6 have shown that they are very eager for oxygen. 



Schutzemberger has stated that fresh yeast put into water well 

 aerated at fermentation temperature is obliged to live at the expense 



1 Lindner, P. Non-assimilability of methyl alcohol by microorganisms capable 

 of assimilating ethyl alcohol. Zeit. Spiritusind. 35, 185; Chemical Abstracts, 6 

 (1912) 1917. 



2 Stockhausen, F. Alcohol assimilation by yeasts. Chem. Ztg. 35, 1197. 

 Chem. Absts. 9 (1912) 4106. 



3 Lindner, P. and Czier, S. Alcohol a more or less excellent nutrient medium 

 for different organisms. Wochenschr. Brau. 29, 1-6; Chem. Absts. II, 476, 6 

 (1912), 1916. 



4 Rubner, M. Assimilation of nourishment by the yeast cells. Cent. Bakt. 

 Abt. II. 38 (1914), 128. Chem. Absts. 9 (1915), 93. 



5 Lindner, P. Results of recent experiments on assimilation by yeasts and 

 molds. Zeit. angewandte Chemie, 25, 1175. Chem. Abstracts 7 (1913) 2055. 



6 Grehant and Quinquand. Ann. des. Sc. nat. Bot. 1889. 



