Effect of Carbon Dioxide on Glucose Metabolism of Trypanosomes

Abstract

In the course of the study of the glucose metabolism of trypanosomes it was found that Trypanosoma lewisi does not decompose glucose under anaerobic conditions unless the solution contains bicarbonate. This effect has been studied during the last 4 years. Although the mechanism of the carbon dioxide action has not been established definitely, some of the main results are given in this preliminary report.

It is well known that the presence of bicarbonate is necessary for the cultivation of certain bacteria. Werkman and coworkers 1 have found that carbon dioxide is actually used up by the propionic acid bacteria, and Wood and Werkman 2 have suggested that the utilization of carbon dioxide is linked with the succinic acid production. They believe that this 4 C atom compound is formed by the addition of CO₂ to a 3 C atom compound by means of a reaction which can be considered to be the reverse of decarboxylation.

Trypanosoma lewisi also forms succinic acid from glucose; this occurs under anaerobic conditions apparently in greater proportions than with any organism or tissue so far studied. At the same time CO₂ is used up. Depending on the concentration of bicarbonate present in the system, the ratio of mols of CO₂ assimilated to mols of glucose used varies from 0.25 to 1.0. The amount of succinic acid produced under these conditions is about 1 mol or sometimes more, per 2 mols of glucose. In addition to succinic acid, lactic acid, pyruvic acid, acetic acid and traces of formic acid are produced by this organism. As stated in a previous paper 3 about 2.5 acid equivalents other than CO₂ are formed per mol of glucose used.