DISCUSSION ON BACTERIAL RESPIRATION 259 



lished the dissimilation of phosphoglyceric to pyruvic acid through 

 phosphopyruvic. 



Pyruvic acid has been shown to be a general intermediate in the 

 dissimilation of glucose by bacteria. In the case of anoxybiontic 

 metabolism the pyruvic acid is converted into a variety of products; 

 in the case of oxybiontic (aerobic) metabolism, however, it appears 

 that pyruvic acid initiates the changes of terminal respiration. These 

 are the changes of the whole aerobic dissimilation, and provide for 

 the oxidation of pyruvic acid to carbon dioxide and water. With 

 respect to bacteria there is evidence that the final processes of 

 respiration involve the cytochrome-cytochrome oxidase system. Both 

 cytochrome and its oxidase have been shown to be present in many 

 aerobic bacteria, and in no case known has cytochrome failed in an 

 aerobic species. There is no doubt that bacteria possess a cytochrome 

 mechanism, although many questions respecting the details of its 

 operation remain to be answered. We have found, for instance, an 

 acetone-resistant cytochrome oxidase not reported in animal tissues, 

 and bacterial cytochrome may have a lower potential than that in 

 animal tissue. 



Between the terminal stage of glycolysis and the initial stage of 

 the cytochrome mechanism there is a portion in the spectrum of 

 respiration that has received only passing investigation so far as 

 bacteria are concerned. This may be referred to as the four-carbon 

 dicarboxylic acid portion. The Szent-Gyorgyi and Krebs schools 

 have pioneered in this work as it relates to animal tissue, and our 

 lead is taken from their work. 



It is this four-carbon acid portion which we wish to discuss first. 

 Mr. Krampitz in our laboratory has been wrestling with these secrets 

 of nature. A few experiments and results will be cited here for pur- 

 poses of discussion. It is hardly necessary to mention that our remarks 

 are preliminary. 



Shortly after Szent-Gyorgyi formulated his theory of the role 

 of the four-carbon acid in cellular physiology, an attempt was made 

 to apply it to bacteria. Before any catalytic eflFect of the four- 

 carbon acids can be shown, the preparation of enzymes must be 

 made deficient in four-carbon acids by washing bacteria free from 

 these acids. Using Micrococcus lysodeikticus to make our prepara- 

 tions, we did obtain stimulation with fumaric acid varying from 35 

 to 120 per cent as measured by oxygen uptake. Such stimulation was 

 not, however, obtained consistently, and therefore we attempted to 

 increase the cell permeabihty by acetone treatment, hoping to re- 



