26 



H. J. Sears 



TABLE 16 



The Production of Amino-acid and Ammonia from Gelatin by Bacteria 

 Total Nitrogen = 828.6 mgm. per 100 c.c. 



The initial decrease in free ammonia is not observed in the sugar- 

 free culture, probably because of the fact that a sample was not 

 analyzed at the end of one day's incubation. This decrease is apparent, 

 however, in the glucose-containing culture, and the latter also shows 

 evidence of the continuous utilization of free ammonia in the falling 

 off of the concentration from 5.9 mgm. per 100 c.c. on the 4th day to 

 on the 7th. Both the ammonia- and the amino-acid-production reach 

 higher values than in the corresponding cultures on peptone alone. The 

 sum of the two forms of nitrogen in the sugar-free culture does not 

 differ greatly, on the last day of the experiment, from that in the case 

 of the sugar-containing cultures, the two sums being approximately 

 2,7% and 39% respectively of the total nitrogen of the sterile medium. 



The spirillum of Asiatic cholera offers a very interesting example 

 of the protein-sparing action of glucose. In the concentrations of 

 both amino-acid and free-ammonia the differences beween glucose 

 and nonglucose cultures are enormous. The data show that in the 

 absence of the carbohydrates the proteolytic activity of this organism 

 is considerable, as great, in fact, as that of B. subtilis or B. pyocyaneus. 

 With glucose present, however, the indication is that the gelatin is 

 attacked very little, if at all, since the figures are much lower even 

 than those shown by this organism on a pure peptone medium (Table 

 3). It is evident that the effect of the sugar is continued throughout 

 the entire time of the experiment. That chemical activity was not 

 brought to a standstill by products of sugar-decomposition is evident 

 from the fluctuating values of ammonia and amino-acid nitrogen. 



