Table No. 2. 



can no longer obtain oxygen from the air it splits up lactose with acid 

 formation. 



Effect of carbohydrates on protein metabolism. 



Protein digestion may, according to Peckh am (6), be approximately 

 estimated in many members of the colon group by the production of 

 indol. Per 6 (1) states that a positive reaction for indol proves the 

 disappearance of sugar in the media. Grape sugar, Kruse (2) thinks, 

 is responsible for the variation in indol production, although he does 

 not state whether the variation is produced by the sugar itself or its 

 decomposition products. Smith (5) thinks the absence of indol in sugar 

 media is due to the presence of acid. Where acid is present no indol 

 is produced, but where acid is absent indol may be formed. A u e r - 

 bach (24) showed that the acid products of fermentation set up by 

 certain bacteria inhibit the formation of the proteolytic ferment. 

 Kalischer (25), in experiments to determine whether the splitting of 

 casein is due to the ferment or the living cell, found that the ferment 

 was able to produce peptone, leucin, tyrosin, as well as ammonia and 

 oxyacids, and is in all probability a tryptic ferment. Cacace (26) came 

 to the conclusion that proteolysis in bacteria is similar to that in higher 

 animals. Wherry (27), working with the cholera spirillum, found that 

 acids produced from glucose, maltose and saccharose rapidly killed the 

 cholera spirillum, while those from lactose and starch are not toxic. 

 This author seems to think that the proteolytic ferment of the cholera 

 spirillum is a tryptic ferment. Marshall (28) observed that Bacillus 

 coli grown at 37 C for five days in 100 c. c. of peptone beef broth 

 containing 20% of lactose failed to produce indol. 



From experiments already cited, it is evident that Proteus vul- 

 garis, under aerobic conditions, does not produce acid in lactose media, 

 while acid is readily produced in dextrose broth. If Smith's conclusion 

 were correct, it was thought that dextrose or any other sugar which can 

 be fermented by Proteus vulgaris, should inhibit the production 

 of indol, while lactose or any other carbohydrate not fermented by this 

 organism should have no eifect on indol production. A series of flasks 

 were prepared, each containing about 100 c. c. of distilled water, to which 

 the percentage of peptone and carbohydrate given in the table had been 

 added. Each flask was inoculated with one loopful of a homogeneous 

 suspension of the bacilli and placed in the incubator at 37 . Five c. c. 

 of broth was removed after 48 hours and 24 hours thereafter for 8 days, 

 and tested for indol with paradimethyl benzaldehyde solution *). 



1) 4 parts paradimethyl benzaldehyde. 

 80 hydrochloric acid. 

 360 alcohol, 95%- 



