220 



FAMILY OF SACCHAROMYCETACEAE 



budding. Colonies on gelatin plates are spherical with a solid appear- 

 ance. In streak culture, the growth is slightly humid and milky. 

 This yeast ferments levulose, dextrose, and saccharose. 



YEAST G. Pearce and Barker 



This species, found in the same environment as the former yeast, 

 generally has oval cells. The maximum temperature for budding is 

 around 32.5 C. (Fig. 90.) Sporulation has been obtained on porous 

 porcelain; it is preceded by a process which seems to 

 be intermediary between iso- and heterogamy. The 

 ascospores are formed in one of the enlarged portions 

 of the asc. (Fig. 23.) Germination is accomplished 

 as in Yeast F. This species develops rather rapidly 

 on beer wort and in all sugar solutions with a scum, 

 m wmcn the cen<s possess the same shape as those 

 (after Pearce and in the deposit. Colonies on beer-wort gelatin are 



Barker). 



dry, spherical and shriveled. In streaks, the 



growth is slightly bunched. This yeast produces no fermentation. 



ZYGOSACCHAROMYCES BISPORUS. Anderson * 



Morphology. In young liquid cultures the cells are oval or ovate ; 

 in old cultures they assume various forms with numerous conjugating, 

 but usually no sporulating cells. Elongated cells 

 are common, but there is no mycelial formation. 

 Budding occurs from end or side. The size is 

 4 X 6.5 microns. Spore formation occurs on 

 carrot slants at room temperature. Conjuga- 

 tion is most common previous to spore forma- 

 tion, but parthenogenesis is not rare. There are 

 2-4 ascospores, most commonly 2. 



Cultural Characters. On glucose agar the 

 growth is spreading, dull, flat, and white; later 

 it becomes brownish with small, scattered, wart- 

 like prominences and more glistening surface. 

 There is a filiform growth in gelatin stab and 

 liquefication in beer-wort gelatin in 3 weeks. 

 Pellicle is present on beer wort and some sugar 

 mediums. 



Physiologic Properties. It does not ferment glucose, sucrose, 

 levulose, maltose, galactose, or raffinose. No decided change in acidity 



Fig. 



90-A. 



charomyces 

 Anderson. 



suiting from Conjugation 

 (after Anderson). 



Anderson, H. W. Yeast-like fungi of the human intestinal tract. 

 Infectious Diseases, 21 (1917) 341-386. 



Jour. 



