A YEAST PRODUCING FOAMY CREAM 295 



The majority of lactose fermenting yeasts have been isolated 

 and studied by European investigators. Grotenfelt (1889) 

 described such a yeast isolated from milk and named it Sac- 

 charomyces acidi-lactici. Beijerinck (1889) isolated a lactose 

 yeast from kefir grains, and one from Edam cheese. The former 

 is known as Saccharomyces kephyr and the latter as Saccharo- 

 myces tyrocola. 



While Beijerinck states that both of these yeasts were Sac- 

 charomyces, other investigators who have studied them assert 

 that both are incapable of sporulating and hence should be classed 

 as Torulae. A non-spore producing yeast was isolated from 

 Grana cheese by Bochicchio (1894) and named Lactomyces 

 inflans-caseigrana. A typical lactose fermenting Saccharomyces 

 obtained from Emmenthaler cheese, is described by Freudenrich 

 and Jensen (1897). Jensen (1902) also noted two species in 

 butter which were true yeasts. Maze (1903) studied ten different 

 torula from soft cheese. One fermented lactose only, while the 

 others fermented glucose, levulose, maltose and sucrose. Duclaux 

 (1900) describes three lactose fermenting yeasts, isolated by 

 Kayser, Adametz and himself. All are non-spore producing 

 yeasts and capable of fermenting glucose, lactose, sucrose, gal- 

 actose, invert sugar and maltose, slightly. All are apparently 

 different species however. Another typical saccharomyces, 

 Saccharomyces fragilis, was isolated from kefir, by Jorgensen 

 (1911). 



According to Lafar (1911) the yeasts of Jorgensen, Freudenreich 

 and Jensen, and Jensen and Maze, are the only lactose ferment- 

 ing yeasts which can definitely be reported as Saccharomyces. 



Yeasts capable of fermenting lactose, according to the present 

 classification are grouped as either true or false yeasts. If true 

 yeasts, they sporulate and hence are considered as belonging to 

 Hansen's fifth subgroup of Saccharomyces, if false yeasts, they 

 are non-sporulating varieties, or Torulae. Of the lactose fer- 

 menting yeasts studied, representatives of both genera are known. 

 The differentiating factor is sporulation and the observations of 

 different investigators, upon this point, for the same yeasts do 

 not agree. Hansen states that the torula may be only a tempo- 



