308 NON-SACCHAROMYCETES OR DOUBTFUL YEASTS 



medium with 1 per cent of glycerol added, it produces a button- 

 shaped growth and a little development along the line of inoculation. 

 It is separated from the yeast of Adametz, which will be mentioned 

 later, by the fact that its branching structure is less developed. In 

 beer wort, similar development is secured. The cells elongate and 

 become cylinders (7ju long). The yeast grows easily in milk and neu- 

 tral serum and develops especially in liquids exposed to the air and 

 with difficulty in the bottom of flasks. The aerobic life does not 

 hinder its enzyme activity. This species secretes neither rennin nor 

 casease but does produce lactase. The optimum temperature for 

 fermentation is between ,25 and 30 C. The thermal death point is 

 50 C. for cells in the dry state and 60 C. for moist cells. No coagu- 

 lation is secured in milk. An alcoholic drink slightly acid and with 

 an agreeable taste is formed from milk. It ferments easily lactose, 

 dextrose, d-galactose, saccharose and more difficultly maltose. 



TORULA LACTIS. (Adametz) Heinze and Cohn 



This species was isolated from a spontaneous fermentation in milk 

 by Adametz. 1 It has oval or elliptical cells (7-10 JJL X 5), sometimes 

 spherical (3-4 jit), larger than those of the preceding species. The buds 

 are usually formed simultaneously at both of the opposite ends of the 

 ellipse. On the plaster block, this yeast forms no ascospores but 

 the cells continue to bud and elongate. On peptone gelatin it does 

 not do well and gives almost entirely a superficial growth. The colonies 

 are round with slightly branching edges and of a brown color. On 

 peptone gelatin with one per cent of glycerol added, in stab cultures, 

 this yeast forms, like the preceding, a superficial button along the 

 inoculation growth from which, in fifteen days, fine branches extend. 

 On beer wort gelatin, an abundant surface growth is secured in which 

 the center is slightly raised. In sterile milk fermentation phenomena 

 are presented in 24 hours at 40 C., in 48 hours at 38 C., and in 4 days 

 at 25 C. No rennin or casease is formed. In beer wort it grows as 

 a sediment at the bottom of the flask and induces a manifest fermen- 

 tation. It starts a faint fermentation in milk after 24 hours a little 

 less vigorous than that caused by the Torula of Duclaux. It fer- 

 ments maltose with difficulty but ferments easily lactose, d-galactose, 

 dextrose and saccharose (as quickly lactose as saccharose). The thermal 

 death point of dry cells is between 50 and 60 C. and of moist cells 

 56 C. 



1 Adametz, L. Saccharomyces lactis, eine neue Milchzucher vergarende 

 Hefenart. Cent. Bakt. 5, 1889. 



