THE EFFECT OF HYDROGEN ION CONCENTRATION ON 

 THE PRODUCTION OF CARBON DIOXIDE BY BACILLUS 

 BUTYRICUS AND BACILLUS SUBTILIS. 



By matilda MOLDENHAUER BROOKS. 



{From the Division of Phannacologyj Hygienic Laboratory, United States Public 



Health Service.) 



(Received for publication, October 3, 1921.) 



In connection with the study of various therapeutic agents and 

 their effects upon the carbon dioxide production of bacteria, it was 

 necessary to investigate the influence of changes in the hydrogen 

 ion concentration before any conclusions could be drawn. 



Clark^ has given a comprehensive bibliography of the influence of 

 hydrogen ion concentration upon various activities. Clark and 

 Lubs^ have given a summary of the limiting reactions which govern 

 the growth of some bacteria. Most of the literature, however, is con- 

 cerned with metabolic activities other than the production of car- 

 bon dioxide. Thunberg^ has observed the effects of various hydrogen 

 ion concentrations upon surviving frog muscle, and has found that 

 there was a considerable decrease in the production of CO2 in both 

 the acid and the alkaline range. 



Gustafson,'* using substantially the same method as the writer, 

 and working with Penicillium chrysogenum, obtained a decrease in 

 the rate of CO2 production when acid was added in quantity sufficient 

 to make the pH 4 or less. He also found a decrease in the rate when 

 the pH of the medium containing the organisms was 8 or more. Be- 

 tween these two concentrations he found no variation in the rate of 

 CO2 production. 



The method used by the writer was that described in a previous 

 publication.^ The apparatus is a closed system, containing at either 



^ Clark, W. M., The determination of hydrogen ions, Baltimore, 1920. 

 2 Clark, W. M., and Lubs, H. A., J. Bad., 1917, ii, 1, 222. 

 ^Thunberg, T., Skand. Arch. Physiol., 1910, xxiii, 154; 1911, xxiv, 23. 

 * Gustafson, F. G., J. Gen. Physiol., 1919-20, ii, 617. 

 ' Brooks, M. M., /. Gen. Physiol., 1919-20, ii, 5. 



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