STUDIES ON THE BIOLOGY OF LACTIC ACID 

 BACTERIA: A SUMMARY OF PERSONAL 

 INVESTIGATIONS' 



COSTANTINO GORINI 



Bacteriological Laboratory of the Royal Superior School of Agriculture, 



Milan, Italy 



Received for publication July 30, 1921 



In the following pages are summarized the most important 

 results of investigations which I have pursued during the recent 

 war period upon the biological characteristics of the lactic acid 

 bacteria. 



ACIDO-PROTEOLYTIC PROPERTIES 



One of the most important characteristics of many lactic acid 

 bacteria is that of possessing acido-proteolytic properties. After 

 the original discovery of this property I have often asserted that 

 this activity must take place in natural milk of acid reaction, but 

 that it is not observed in milk which has received the addition of 

 chalk or other substances, since these additions not only alter the 

 composition of the milk but also so alter its adaptability for the 

 growth of the organisms concerned that the natural functions of 

 the latter are no more exhibited and thus the results obtained in 

 the study are no longer apphcable directly to normal conditions 

 such as occur in the cheese industry. 



The detection of this acido-proteolytic property is very simple 

 and indeed requires no chemical manipulations. Just as the 

 Uquefaction of gelatin indicates proteolytic properties, the casein 

 cleaving properties of these organisms are indicated by the 



'The investigations covered by this summary have been published in the 

 transactions of the Reale Accademia dei Lincei of Rome and the transactions of 

 the Reale Istituto Lombardo di Scienze e Lettere of Milan during the years 

 1914-1920. 



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