64 



THE FORMATION OF ENZYMES IN BACTERIA 



CHEMICAL CONSTITUTION OF THE MEDIUM . 

 Presence of substrate 



This subject has been studied in considerable detail by 

 Karstrom, who found that the ability to ferment certain 

 sugars is often acquired only if growth takes place in the 

 presence of those sugars. Table V shows the variation of 

 the fermentation abilities of Betacoccus arabinosaceus with the 

 nature of the sugar present during growth. From the table 

 we can see that this organism ferments glucose and sucrose 

 whether these sugars are present in the growth medium or 

 not, but the fermentation of galactose, maltose, lactose, and 

 arabinose will take place only if growth has occurred in the 

 presence of galactose, maltose, lactose, or arabinose respectively. 

 Galactose can be fermented if growth has taken place in the 

 presence of lactose, since growth in lactose results in the 

 liberation of galactose from the lactose molecule. 



TABLE V 



Relation of Febmentative Properties to Nature of the Sugar 

 Present during Growth (Betacoccus arabinosaceus) 



Karstrom therefore divided bacterial enzymes into two 

 classes : 



