332. NON-SACCHAROMYCETES OR DOUBTFUL YEASTS ' 



The cells are oval and contain two vacuoles filled with refractive gran- 

 ules. At the beginning of their development the cells are united in 

 budding chains. Later they separate. In old cultures, the yeast 

 takes irregular shapes, some cells becoming angular. De Seynes 

 thought that he saw ascospores in this species. This work was re- 

 peated by Engel, Reess and Cienkowski but not confirmed. It is 

 then probable that these pretended ascospores were fat globules. 

 Mycoderma vini is capable of changing the taste of wine. It con- 

 tributes what is called the bouquet. It oxidizes alcohol, changing it 

 into carbon dioxide and water with the production of acid. It does 

 not attack tartaric very much and citric not at all, but destroys acetic 

 acid and glycerol. 



According to Siefert, 1 it is necessary to distinguish two types of 

 Mycoderma vini: Mycoderma vini I and Mycoderma vini II. The 

 first possesses cells 3 to 10 ju long and from 2 to 4 /z wide. The 

 scum is at first smooth, later folded and grayish in color. The tem- 

 perature limits for budding in wine with 8 per cent of alcohol 

 added, are minimum, 5-6 C., optimum, 25-20 C. and maximum, 30 C. 

 This species requires alcohol for development and attacks malic acid. 

 In solutions containing 4.8 per cent of alcohol and malic acid, 1.52 

 per cent of glycerol is formed in 14 weeks. All of the alcohol is de- 

 stroyed. In Austrian wine, in 26 days the amount of glycerol changes 

 from 6.8 per cent to 82. It forms 9.04 per cent of acetic acid and the 

 amount of alcohol changes from 7.8 to 3.8 per cent. 



Mycoderma vini II has temperature limits lower that those for 

 the above yeast : minimum, 1 to 2 C. , optimum, 22 C. and maximum 

 28 C. to 30 C. It attacks malic acid only feebly. In Pasteur's 

 solution in a week it gives 0.16 per cent of glycerol. The amount of 

 alcohol is 4.8 to 4.1 per cent by volume. In Austrian white wine, after 

 26 days no increase in the amount of glycerol is accomplished. There 

 is formed, however, 0.64 per cent of acetic acid. The quantity of 

 alcohol decreases from 7.8 to 6.8 per cent by volume. 



In a recent investigation, Gino de Rossi has shown that the 

 species Mycoderma vini is really made up of a series of distinct va- 

 rieties. By isolating the mycodermic forms from grape must or 

 wine, which had been exposed to the air, this author has been able to 

 characterize the species. 



Mycoderma vini. On grape must, the cells are variable in form, 

 oval, or elongated cylinders (5.6-9.5 X 2.8-4.8 ju), united in small 

 groups which branch, but which separate in from 4 to 8 days into 

 large cells with from 2 to 3 refractive granules. On gelatin with 10 



1 Siefert. Saccharomyces membranaefaciens. Ber. chem. physiol. Versuchsst. 

 Klosterneuburg, 6, 1899-1900. 



