Apr. 22, 1918 



Bacterial Flora of Roquefort Cheese 



227 



BACTERIAL FLORA OF IMPORTED ROQUEFORT CHEESE 



Bacteriological analyses of a number of imported Roquefort cheese have 

 been made and the data are presented in Table I. Most of the imported 

 cheese obtained for study was well ripened when the analysis was made. 

 Cheeses 13, 146, 148, and 150 were not well ripened, but they must have 

 been several weeks old, for Streptococcus lacficus, which certainly must 

 have been present in the cheesemaking, had disappeared entirely from 

 every sample examined. 



TablS I. — The bacterial flora of irtiported Roquefort cheese 



Cheese No. 



IS- 

 IS- 

 17- 

 18. 



131 

 135 



Number of organisms per gram 

 of cheese. 



Cheese 

 streptococci. 



31,000, 000 



600, 000 



13, 000, 000 



30, 000, 000 



I, 400, 000 



17, 000, 000 



140, OCO, 000 



Bacterium 

 bulgaricum. 



100, 000 



400, 000 



4, 000, 000 



145, 000 



4, 000, 000 



Cheese No. 



Number of organisms per gram 

 of cheese. 



137 

 139 

 141 



143 

 146 

 148 

 150 



Cheese 

 streptococci. 



600, 000 



10, 000 



100, COO, 000 



I, 000, 000 



210, 000 



I, 000, 000 



1,000 



Bacterium 

 bulgaricum. 



I, 000, 000 



1, 000 



I, 000, 000 



I, 000, 000 



250, 000 



24, 000, 000 



10, 000 



Two groups of bacteria were found to be the common flora of this 

 type of ripened cheese: Boot. bulgaHcum, and a group of organisms 

 which here will be called "cheese streptococci." ^ 



Table I shows that cheese streptococci in varying numbers, with 

 140,000,000 per gram as the highest number, were isolated from every 

 one of the imported cheeses, and Bact. bulgaricum was isolated from all 

 but one of them, wdth 33,000,000 per gram as the highest number. It 

 most probably was present in the one cheese also, but failed to be 

 isolated. Yeasts were isolated from a few of the cheeses, but in too 

 small numbers to be considered of any significance. 



BACTERIAL FLORA OF EXPERIMENTAL CHEESE MADE ACCORDING 

 TO THE ROQUEFORT METHOD 



For several years experimental cheese has been made in the Dairy 

 Division according to the method by which Roquefort cheese is made, 

 but with cows' milk instead of sheep's milk. The ripened cheese is 

 very similar to the imported variety in appearance and flavor. The 

 data obtained from a detailed study of the bacterial flora of the experi- 

 mental cheese are given in Table II. 



1 The cheese streptococci are the subject of an accompanying paper (j). Culturally they are distin- 

 guished from Streptococcus lacticus by a failure to curdle litmus milk with the reduction of the litmus 

 characteristic for that organism. 



