PRODUCTION OF VOLATILE FATTY ACLDS 



^ Ui Glucose „ Aerobic. 



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iT? 8 j'a. /6 io a4 aa ^8 7i 36 /Vrs. 



Fig. 1. Volatile fatty acid production curves of Di grown in 1,000 cc. of 

 medium, and under the conditions indicated. 



CONCLUSIONS. 



These studies show: 



1. A close agreement exists among all the organisms studied in the 

 total quantity of volatile fatty acids produced and in the ratio of 

 formic to acetic, under aerobic conditions, and in the presence of 1 

 per cent of glucose. 



2. When grown uppn peptone alone, with free access of air to the 

 cultures, volatile fatty acids are produced in appreciable quantities, 

 although the reaction of the solution has gone more alkaline as shown 

 by colorimetric pH tests. Formic acid is not found, but in its place 

 we obtain propionic acid. 



3. Upon exhaustion of air from the non-sugar medium the bacteria 

 again produce formic acid, and in addition some butyric. This is 

 true for both Shiga and non-Shiga cultures. The reaction is dis- 

 tinctly more acid. 



4. The presence of glucose in the medium from which the air has 

 been pumped furnishes a condition which provokes about the same 

 type and degree of fermentation that operates in the glucose medium 

 bathed in air at atmospheric pressure. 



5. The enormous quantity of formic acid produced by these bacteria 

 may play a significant part in the digestive disturbances and toxic 

 S3nnptoms accompanying their infection of the human intestinal tract. 



