228 BACTERIA IN CHEESE MAKING. 



teria are apt to be abundant in the fresh cheese and these 

 organisms, since they digest casein, have been supposed to be 

 the cause of the ripening. But during the ripening period 

 these organisms, instead of multiplying, constantly decline in 

 numbers, never becoming more numerous than at the outset. 

 In nearly all cases they disappear in the course of a com- 

 paratively few days. On the other hand, the lactic bacteria, 

 chiefly the first of our types (page 65), increase pro- 

 digiously in the first few days, though they afterward decline 

 rapidly, and later more slowly. These facts would seem to 

 indicate that the lactic organisms are more intimately con- 

 cerned in the ripening phenomena than the enzyme-producing 

 bacteria, at least in the case of hard cheeses. 



There has been considerable dispute among bacteriologists 

 as to the relation of microorganisms to the cheese ripening. 

 When the subject was first discussed by Duclaux it was 

 assumed that the peptonizing bacteria were chiefly concerned, 

 inasmuch as these organisms were known to produce a 

 digestion of the casein. Many others adopted Duclaux's 

 position, and, up to very recent times, it has been assumed 

 that this conclusion was correct. But the fact that the 

 peptonizing bacteria constantly decline in numbers while the 

 acid bacteria increase very greatly, has led recently to the 

 belief that the lactic organisms are concerned in the phe- 

 nomena rather than the peptonizing types. An objection to 

 this view has been the fact that the lactic bacteria have not 

 been known to produce a digestion of the casein, such as 

 characterizes cheese ripening. Good reasons have, however, 

 been given for believing that, under proper conditions, the 

 lactic organisms may produce a peptonizing of the casein, 

 and recent experiments have practically demonstrated the 

 conclusion that, to the lactic, rather than the peptonizing, 

 organisms is to be attributed the ripening of, at least, the 

 Swiss cheeses. 



