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BACTERIOLOGICAL CHEMISTRY 



The enzyme fermenting xylose is adaptive, and since 

 the organism was grown on a lactose medium it did not 

 contain the xylose enzyme. In solutions 1 and 2 there 

 was no growth of the cells (owing to lack of a nitrogen 

 supply), and so xylose was not fermented. In solutions 3 

 and 4, however, nitrogen was present, growth (or at least 

 synthetic activity) occurred and a delayed fermentation 

 of xylose took place after the necessary enzyme had been 

 elaborated. 



In other experiments Karstrom grew the pentose 

 fermenting lactic acid organism, Leuconostoc mesenter- 

 oides (Betacoccus), on media containing only one of a 

 series of sugars, separated and washed the cells and 

 tested their fermenting ability on other carbohydrates, 

 with the results show in Table 6. 



Table 6 



The glucose, fructose, mannose and sucrose fermenting 

 enzymes are thus seen to be constitutive since they are 

 produced when the organism is grown on any sugar 

 medium, and even on media containing no sugar at all. 

 The other enzymes fermenting galactose, arabinose, 

 maltose and lactose are adaptive since they are only 

 developed in the presence of the appropriate substrate 



