Bacteria and the Ripening Process 421 



ing process. Indeed, numerous attempts have not been 

 wanting to prove that they are thus directly concerned. 

 However, the adherents of this theory have a serious 

 difficulty to overcome in proving that the lactic -acid 

 bacteria are capable of causing the digestion of protein 

 substances and the formation of amides and of ammonia. 

 In some instances, it was undoubtedly demonstrated 



!> . 



S 



/ 



:. 



^ $2iPo 



30^*0'^,^ 



kP n 0- -~ *. 



* -T O0*o0 



^ CO ' ^ 



Fig. 64. Bacteria in cheese-ripening. 1 and 2. Sections through Emmentaler 

 (Swiss) cheese, showing enclosed bacteria. 3. Section through Gorgonzola 

 cheese. (Rodella.) 



that there are species of lactic-acid bacteria that pro- 

 duce proteolytic, that is, protein-digesting, enzymes. 

 Most investigators, however, have been unable to dis- 

 cover the production of such enzymes by the lactic-acid 

 bacteria. The question as to the direct influence of these 

 organisms in the ripening of cheese is, therefore, still 

 an open one. 



On the other hand, it is generally agreed that the 

 lactic-acid bacteria are indirectly of great moment for 

 the ripening process. Their rapid increase in the fresh 



