236 Journal of Agricultural Research vo>. xiii, No. 4 



The streptococci concerned in cheese ripening, 5. lacticus and the 

 other varieties described in this paper, comply with the generic descrip- 

 tion in every detail except in regard to parasitism. The cultural char- 

 acteristics of the group are too well known to be described further in 

 this paper, which has to do with a classification of those streptococci 

 that act as ripening agents in cheese and other food substances. 



Streptococci agreeing with the genus description given above, and 

 differentiated from 5. lacticus by their growth in milk culture, have 

 been isolated from many kinds of cheese by several investigators. As 

 the data to be presented will show, the manner of growth in litmus milk 

 is a reliable characteristic for the differentiation of 5. lacticus from other 

 distinct varieties of streptococci which are normal inhabitants of various 

 kinds of cheese. Therefore it may be safely assumed that the investi- 

 gators in question were dealing with varieties of streptococci other than 

 5. lacticus. For convenience in discussion in this paper, all other types 

 of streptococci as distinguished from 5. lacticus will be called "cheese 

 streptococci." Henrici (//) found them in Schweitzer, Edam, Gouda, 

 Port du Salut, American, I^auterbacher, Monsheimer, Miinster, Limburg, 

 Spunden, Schloss, Cantal, Brie, cream, and Neufchatel cheeses. Troili- 

 Petersson (21) found them in what the Germans call Swedish Giiterkase, 

 Eldredge and Rogers (4) found streptococci in Emmental cheese. Evans, 

 Hastings, and Hart (o) reported that they are active agents in the 

 ripening of Cheddar cheese. In an accompanying paper (7) they are 

 shown to be one of the predominating types of bacteria in Roquefort 

 cheese. 



Thus, it has been shown that cheese streptococci are present in both 

 hard and soft cheeses made by various methods in different countries. 

 Freudenreich (9) found streptococci that were identical with one of the 

 varieties described in this paper to be active in the preparation of "kefir," 

 and Saito (ly) found that these same organisms were active in the fer- 

 mentation of the mash from which the Japanese condiment "soya" is 

 prepared. The writer has found similar streptococci in the Chinese 

 "toku," or soybean cheese. It is probable that they are active in the 

 fermentation of other foods. 



The source of the cheese streptococci is suggested by the fact that other 

 bacteria concerned in cheese making and cheese ripening. Bacterium 

 bulgaricum and S. lacticus, are normal inhabitants of the intestines and 

 saliva of animals. Some strains of the cheese streptococci agree in every 

 detail with the published descriptions of 5. mitis; others agree with 

 the descriptions of 5. jaecalis, both of which are streptococci normally 

 inhabiting the mouth and intestines of men and domestic animals. 

 Other cheese streptococci differ from the species mentioned only in 

 fermenting slightly different combinations of test substances; hence, it 

 appears that the cheese streptococci get into the milk with the filth of 

 the stable. Those which multiply in cheese must be particularly hardy 



