Apr. 22, 1918 Streptococci Concerned in Cheese Ripening 243 



The order of availability of the fermentable test substances is some- 

 what different from that for 5". laciicus. In both groups lactose is fer- 

 mented by every strain. The fermentation tests were made for 27 

 strains of Streptococcus X in addition to the 13 strains included in the 

 table. Every one of the 40 strains fermented salicin. All but 2 of the 

 strains, 2ac and 2ae (Table II), or 95 per cent, fermented glycerin; 27, 

 or 67.5 per cent, fermented mannite; and 14, or 35 per cent, fermented 

 sucrose. The order of availability of the test substances of Streptococ- 

 cus X is, therefore, lactose and salicin, glycerin, mannite, sucrose. The 

 high percentage of positive reactions in glycerin broth characterizes 

 this group as compared with 5. lacticus. RaflEinose was not fermented. 



Under the conditions of the tests, the final hydrogen-ion concentra- 

 tions in fermented broths varied widely, and failed to characterize the 

 group. In glycerin broth the final hydrogen-ion concentration was 

 notably less than in the other fermented broths. 



STREPTOCOCCUS KEFIR 



This organism was first isolated by Freudenreich (9), who called it 

 "Streptococcus b." Migula (15) gave it the name "Streptococcus kefir." 

 Under the name "Bacterium soya," Saito (17) described an organism 

 which is apparently identical with this one. Out of consideration for 

 priority in names, this group of organisms should be called "Streptococ- 

 cus kefi,r." 



There is nothing characteristic about the morphology of 5. kefir. 

 In the condensation water from agar slopes it occurs in pairs, and occa- 

 sionally short chains are formed. It has not so pronounced a tendency 

 to group formation as Streptococcus X, but occasionally groups of from 

 four to six cells are to be found. 



Freudenreich found S. kefir to be a predominating organism in kefir. 

 Saito found it to be one of the organisms concerned in the fermentation 

 of the mash in the preparation of the Japanese condiment soya. It 

 has been found in very great numbers in Roquefort and Cheddar cheese. 

 No doubt a further search for this organism will show that it is impor- 

 tant in the fermentation of other kinds of food substances, as well as 

 other kinds of cheese. In Table III, where the data for this group are 

 summarized, the strains numbered 96 are from imported and experi- 

 mental Roqufort cheese, and the strain numbered 2 is from Cheddar 

 cheese. 



In litmus milk growth is slow, and the milk is rarely brought to cur- 

 dling. Usually the acidity is only slight. There is no reduction of litmus. 

 In peptone milk the behavior of S. kefir is striking and distinguishes it 

 from all other known streptococci of food and dairy products. The 

 peptone milk is acidified rapidly, with curdling in from three to six days. 

 The curd is rent with escaping gas, and gas bubbles can be seen rising in 

 rapid succession. 



