Apr. 22, 1918 Streptococci Concerned in Cheese Ripening 



241 



hydrogen-ion concentration in the broth medium used in this study does 

 not aid in the classification of the streptococci under consideration. It 

 may be possible to devise a medium in which the final hydrogen-ion 

 concentration of the different varieties would be characteristic. 



Table I. — Characteristics of Streptococcus lacticus 



Culture 

 No. 



Changes in litmus 

 milk. 



Cur- 

 dliag. 



Reduction. 



Crys- 

 tal:, in 

 milk. 



96mz 

 96ga. 



2ak. . 

 96hr 

 96hs . 

 2al.. . 

 aao . . 

 2an. . 

 2ab. . 

 96ht , 

 2ap. . 



Days. 



Complete 

 ...do 



.do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 



+ 

 + 

 -1- 



+ 



+ 



+ 



+ 

 -i- 



+ 

 + 



Quantity 

 of Nlio 

 acetic 

 acid in 

 500 c. c. 

 of milk. 



Final Ph 

 values in 

 peptone- 

 yeast 

 broth 

 (Ph=6.o). 



Final Ph values in fermented broths." 



Lac- 

 tose. 



Sali- 

 cin. 



50 

 4. I 



4-7 

 4.6 



5 o 



50 



4-7 



4- 



4- 



4- 



4- 



4- 



4-7 

 5-2 

 5-2 

 4-7 

 4-7 

 4.6 



4-7 

 A. 6 



4.6 



Man- 

 nite. 



Su- 

 crose. 



4.2 

 4. I 

 4.4 

 4.4 



Raffi- 

 nose. 



Glyc- 

 erin. 



o The minus sign (— ) indicates failure to form acid. 

 STREPTOCOCCUS X 



It was stated above that after applying to all the streptococcus cultures 

 isolated from cheese the biochemical tests which served to characterize 

 S. lacticus, two other species were recognized. One of them is designated 

 Streptococcus X, which is merely a tentative appellation to serve until a 

 better knowledge of the milk and cheese streptococci is at hand. The 

 relation of this group of organisms to cheese ripening will be discussed 

 later in this paper. To anticipate that discussion it may be stated here 

 that Streptococcus X brings about changes in ripening cheese which are 

 easily distinguishable from the changes caused by 5. IcLcticus. This is 

 one of the most forceful arguments to justify considering it a species 

 distinct from 5. lacticus. 



Morphologically Streptococcus X differs slightly from S. lacticus. In 

 the condensation water from agar slopes the cells occur commonly in 

 pairs and under some conditions the cells are elongated and slightly 

 pointed at the ends. But Streptococcus X has more of a tendency than 

 5. lacticus to form groups of from two to seven cells. This grouping of 

 cells often suggests that they may belong to the micrococci rather than 

 to the streptococci, but short chains of from four to eight cells are to 

 be found in almost every culture. In dextrose broth long chains are 

 formed, which classifies the group definitely with the streptococci. 



