210 



FAMILY OF SACCHAROMYCETACEAE 



swelled parts connected by a canal and offer a resemblance to the 

 ascs of the Zygosaccharomyces and we shall not hesitate to attach this 

 yeast to this genus although copulation has not been observed up 

 to the present time. (Fig. 86.) 



The ascospores are generally to the number of from 1 to 4 per asc 

 and are located in each part of it. They are 

 spherical, hyaline and possess a resistant wall. 

 Their diameter is from 2.7 to 4.5 microns. 



Giant colonies are a grayish brown color; 

 they are raised in the center and have a greatly 

 notched edge. On plates, colonies are produced 

 which resemble dots, round and moist. On 

 gelatin streaks or stabs the yeast offers a greenish 

 Cells and KSa? *>? coloration along the line of inoculation and on 



Zygosaccharomyces the surface a grayish yellow. Zygosaccharomyces 

 Soya (after Saito). , , i i j 



soya ferments dextrose, levulose, d-mannose, 



d-galactose and maltose easily. It does not act on saccharose, inuline, 

 a-methylglucoside, lactose, melibiose, or raffinose. It inverts sac- 

 charose but does not ferment it. Its invertase does not pass through 

 the cell wall and is, therefore, an endoenzyme. 



ZYGOSACCHAROMYCES LACTIS a. W. Dombrowski 



This species isolated by Professor Jensen from beer has been 

 described by Dombrowski 1 (1910). On beer wort the cells are spheri- 

 cal and have an average diameter of 4.7 JJL. Sporulation is preceded 

 by an isogamic copulation which is 

 effected after the normal procedure. 

 The ascs which result are made up of 

 two enlarged portions connected by a 

 canal. (Fig. 87, 2 and 3.) The asco- 

 spores are formed in these two enlarged 

 parts and vary from one to four in each 

 asc. Germination is accomplished by an 

 absorption of the wall of the asc after 

 which ordinary budding is accomplished. 

 This species produces, on beer wort at 

 room temperature, a scant scum made 

 up of cells with a normal shape. 



The colonies on plates are lenticular 

 and are round or torpedo shaped. In stab cultures the growth extends 

 about 3.5 centimeters below the surface. Giant colonies offer a crater- 



Fig. 87. Zyg. Lactis a. 



Vegetative cells. 2 and 3. Ascs (after 

 Dombrowski). 



1 Dombrowski, W. 

 28, 1910. 



Die Hefen in. Milch und Milchprodukten. Cent. Bakt. 



