A Simple Respirometer for Microbial Respiration.

Abstract

Since the comprehensive work of Novy, Roehm and Soule 1 on microbic respiration appeared in 1925, an effort has been made to devise a simple apparatus for determining CO₂ production in cultures which would be simple and available for ordinary laboratory use. It is doubtful if any device known at present will give the fine results which Novy, Roehm and Soule are able to obtain with the compensation manometer.

Bronfenbrenner 2 described a simple micro-respirometer in 1926 using as a test object a strain of bacteriophage. He was unable to demonstrate that the bacteriophage respired. In a more recent report this author has studied the respiration of the herpes virus and of rabies virus 3 . In this study in order to differentiate between the respiration of tissue and that of the filterable virus he made use of the Warburg 4 respirometer to determine the oxygen uptake and of his closed cell respirometer for the respiration proper.

Bertrand5 was perhaps the first to make use of an alkali trap for the absorption of respired CO₂. In searching for some simple method to demonstrate microbial respiration to students in bacteriology we decided to make use of this simple procedure. From ordinary culture tubes containing smaller tubes within, which served for a trap, a more elaborate apparatus has been devised by which it is possible to make quantitative tests for respiration as well as qualitative tests.

Figure 1 shows such an apparatus in the form of a flask carrying a side chamber which serves as the trap. The flask E is of 100 cc. capacity. It is entered through stop-cock B and can be exhausted

through C. Substances can be introduced and withdrawn through inlet tube D. The side chamber H is fitted into flask E through a ground joint F and this joint is further protected by a mercury seal G.