ZYGOSACCHAROMYCES NADSONII 213 



ZYGOSACCHAROMYCES NADSONII. Guilliermond 



This species was isolated by Guilliermond l from a large bottle 

 of orange syrup at Hospital 101 at Lyon during the summer of 1915. 

 In this it caused a very active fermentation. After 12 hours in beer 

 wort at 25-30 C., this yeast forms a white deposit at the bottom 

 of the flask. In a few days there is produced over the surface of 

 the liquid a very delicate covering. Later a ring develops which 

 falls to the bottom of the flask when it is disturbed. This ring 

 does not seem to re-form. The cells are generally round or oval in 

 beer wort cultures which are 12 hours old. 

 Sometimes they are isolated but generally 

 they adhere in a small group; after 24 

 hours this tendency is greatly increased. 

 The cells are generally round or oval and 



form buds around their peripheries. The Fig- 88-E. Zygosaccharo- 



,, 11 ,T e m 7 A^ myces chevalien. 1, Cells 



cells may resemble those of Torula. After f rom Sediment in Beer Wort 



8 to 14 hours the elongated cells may be- 24 Hours at 25 C.; 2, Asco- 



come rather numerous. On must agar, the 



colonies develop quickly; on carrot, a white blanket growth is formed. 



The minimum temperature seems to be situated between 3 and 5 C. 

 At 5 C. and up to 15 C. the yeast develops slowly. At 18 C. and 20 C. 

 its development becomes more rapid. The optimum temperature is 

 situated near 30 C. and the maximum is between 41 C. and 42 C. 

 In the vicinity of these temperatures the yeast shows a tendency 

 to elongate and form cells like the Pastorianus type. 



The ascospores form very abundantly after a few days on Gorod- 

 kowa's media. They seem to be formed in great numbers but less 

 rapidly on carrot and beer wort agar. The ascs result almost uni- 

 versally from a heterogamic conjugation. It is very easy to follow 

 all the stages in this phenomena in a culture on Gorodkowa's agar. 

 At the moment when conjugation is about to occur most of the cells 

 affected show in their center a large number of small fat globules. 

 Almost all are united in small colonies made up of a small number 

 of cells. Conjugation is effected between a mother cell and an in- 

 completely developed daughter cell. The mother cell plays the role 

 of a female gamete while the daughter cell represents the male gam- 

 ete. The gametes are then represented by cells of different ages. 

 The male gamete (microgamete) is a cell which has not achieved its 

 full growth, while the female gamete (macrogamete) is full grown. 



1 Guilliermond, A. Zygosaccharomyces Nadsonii. Nouvelle espece de levures 

 a conjugaison he"te"rogamique. Bull. Soc. de France, 34 (1918). 



