CHAPTER XI 

 THE NON-SACCHAROMYCETES OR DOUBTFUL YEASTS 



T 



HIS is a provisional group in which one may place all yeasts 

 which do not form ascospores and whose places in classifica- 

 tion are uncertain. 



Genus Torula. Turpin 



Under the name Torula, 1 Hansen has grouped a large number of 

 asporogenic species often capable of fermenting sugars, among which 

 are some which do not form a scum and others which form a ring around 

 the culture flask or scum without the interposition of air, analogous 

 to those which are produced by the Saccharomycetes of the third 

 group. The greater number of the Torulae possess regular spherical 

 cells and contain a globule of fat which gives them a special charac- 

 teristic. They may, then, be regarded as asporogenic Torulaspora. 

 But some are oval or elongated and offer the appearance of ordinary 

 yeasts. A certain number of them form a red, black or brown pig- 

 ment. The formation of these pigments seems to depend, at times, 

 on the presence of silver in the medium. Light sometimes represses 

 the production of pigments. The investigations of Chapman seem to 

 indicate that the coloring matter in red torula is due to some other 

 substance along with carrotene. The Torula are very widespread in 

 nature. They are encountered in the soil, breweries, insects, milk, 

 in secretions of trees, etc. 



A. TORULA FROM BREWERIES AND OTHER SOURCES 



HANSEN'S TORULA 



Hansen 2 has described a number of Torula which we shall now 

 consider. 



Torula No. 1. It appears in beer wort as isolated cells or as 

 colonies formed by a small number of cells. The cells are 1.5 to 4.5/4 

 in diameter and often have a large vacuole with a large refractive 

 body. This yeast forms a small amount of alcohol in beer wort and 

 does not secrete invertase. 



1 This name leads to confusion for it is also applied to the Mucedinaceae, 

 very different from the yeasts (genus Torula of Persoon); in spite of this the 

 name is commonly used. 



2 Hansen, E. C. Sur les Torula de M. Pasteur. Comp. Rend, des trav. 

 du lab. de Carlsberg, 2, 1888. 



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