BACTERIAL METABOLISM WITHIN THE BODY 671 



proteus prior to inoculation [to the extent of 0.5 per cent or more] will, 

 so alter the products of growth that the soluble proteolytic enzyme and all 

 other evidences of proteolytic and putrefactive activity are no longer 

 detectable in the culture medium (Kendall and Walker). On the con- 

 trary, lactic and other acids indicative of the fermentation of carbo- 

 hydrates are formed. Here again the addition of glucose in a minimal 

 amount of 0.5 per cent has completely altered the products of growth. In 

 other words, from the illustrations cited, small amounts of glucose pre- 

 vented the formation of toxin in cultures of the diphtheria bacillus, of 

 indol in cultures of Bacillus coli and Bacillus proteus, and of a soluble 

 proteolytic enzyme in cultures of the cholera vibrio and Bacillus proteus. 

 If space permitted, examples of the sparing action of utilizable carbo- 

 hydrate for protein as sources of energy might be cited from all fields of 

 bacterial activity, but those herewith presented are illustrative. Ad- 

 ditional observations of specific interest are discussed . in appropriate 

 sections. 



It is worthy of note that a minimum of 0.5 per cent of glucose was 

 specified in each instance. Experience has shown that the diphtheria 

 bacillus can utilize from 0.1 to 0.3 per cent of glucose without producing 

 enough fermentation acid and other products of the cleavage of glucose to 

 inhibit its further growth (Theobald Smith). Under these conditions 

 no toxin is demonstrable until the sugar [glucose] has disappeared. Then 

 toxin begins to form. 



Bacillus coli and Bacillus proteus do not form indol in culture media 

 until the utilizable sugar is used up. If the amount of sugar is somewhat 

 less than 0.5 per cent, the products of fermentation incidental to the 

 utilization of it for energy do not inhibit the subsequent development of 

 the colon or proteus bacilli, and the formation of indol proceeds after 

 the glucose is fermented. 



Similarly, relatively small amounts of glucose or other utilizable car- 

 bohydrate, somewhat less than 0.5 per cent the limit of tolerance varies 

 somewhat with the strain of the organism prevent the formation of pro- 

 teolytic enzymes by cholera, proteus and other bacilli. When the carbo- 

 hydrate is used up, however, provided the conditions due indirectly to the 

 accumulation of products of fermentation are not too unfavorable, the 

 organisms attack the protein constituents of the medium for their energy, 

 and the proteolytic enzyme makes a belated appearance. It should be 

 emphasized that the presence of glucose, or other utilizable carbohydrate 

 in cultures of cholera, proteus, or other bacteria, which form a soluble 

 proteolytic enzyme, prevents the formation of the enzyme in the reactive 

 state. Neither glucose nor any other carbohydrate prevents the action of 

 the mature, reactive proteolytic enzyme when it has been elaborated (Ken- 

 dall and Walker (&)). In other words, when the enzyme is formed in an 

 active state, as for example in sugar-free media, this bacteria-free enzyme 



