HYDROCARBON COMPOUNDS 75 



alcohol, amyl alcohol or lactic acid. Cultures in glycerol and ethyl 

 alcohol grew as well as the control in sucrose. Cultures in lactic acid, 

 methyl alcohol and amyl alcohol grew slightly, and formed sufficient 

 tyrosol for isolation. Since tyrosol corresponding to nearly all of the 

 tyrosine was obtained, it shows that when the carbon diet is limited 

 to simple compounds, the yeast does not utilize the carbon of amino 

 acids. 



. 



3. Hydrocarbon Compounds 



The yeasts, being, like the fungi, without chlorophyll, are not able 

 to take their carbon from the atmosphere. They have to resort to 

 other compounds as sugars, aldehydes, acids, etc. 



The hydrocarbon metabolism of yeasts ought to be looked at from 

 two standpoints. One should distinguish the hydrocarbon metabo- 

 lism of the yeasts during the aerobic life, that is the plant-yeast, 

 and also during fermentation, yeast-ferment. In the two cases, they 

 act differently. The first of these will be treated here, and the other 

 when we take up alcoholic fermentation. 



From the experiments of Laurent, 1 it is evident that the alcohols, 

 aldehydes, ethers, fatty acids, amides, glycocoll, hydroquinone, and 

 cellulose are not able to liberate their carbon to the yeasts. On the 

 contrary, the yeasts are able to take it from acetates, lactates, cit- 

 rates, tartrates, malates, succinates, tartaric acid, malic acid, succinic 

 acid, lactic acid, glycerol, from sugars of the CeH^Oe and C^H^On 

 series, and from substances capable of transforming into glucosides 

 dextrine lecithin, asparagin, peptones, etc. Bokorny has also reached 

 about the same conclusion. 



It seems that alcohol, which these authors regard as not used by 

 yeasts, is able, however, to be used by certain species. 2 Thus it is 

 that recent investigations by Trillat and Sauton, 3 Kayser and Demo- 

 Ion 4 indicate that they oxidize alcohol to the aldehyde. 



The investigations of Lindner and Saito 5 indicate that maltose 



1 Laurent, E. Nutrition hydrocarbone*e et formation du glycogene chez la 

 levure de biere. Ann. Past. Inst. 3, 1889. 



2 We shall see that yeasts are able to live for many years in liquids which 

 they have fermented. It is probable that they use the glycerol and succinic 

 acid (which are regarded by Laurent as being able to supply the needs of yeasts 

 for carbon). For certain species alcohol seems to be the source of carbon. 



3 Trillat and Sauton. L'aldehyde ac^tique est-il un produit normal de la 

 fermentation alcoolique? Ann. Inst. Past. 24. 1910. 



4 Kayser and Demolon. Sur la vie de la levure apres la fermentation alcooli- 

 que. Comp. Rend. Acad. Sci. 149. 1909. 



6 Lindner, P. and Saito, K. Assimilierbarkeit verschiedener Kohlehydrate 

 Hefe. Woch. Brauerei No. 41. 1910. 



