Oxidation-Reduction Studies of Growth and Differentiation of Species of Brucella

Abstract

The object of this investigation has been to determine the oxidationreduction potentials associated with the growth of strains of Brucella melitensis, Brucella abortus and Brucella suis in a suitable liquid culture medium in the presence of and without the addition of certain growthinhibiting dyes. It was thought that the results of such a study might furnish further information'on the biologic relationships of the three species and enlightenment as to the mechanism of the selective action of the dyes on the growth of Brucella.1 It is obvious that in making a comparative study of this nature on closely related aerobic bacteria, the growth conditions that are maintained should closely approximate those normally used in growing the organism. In other words, if there are metabolic differences in intensity and capacity in the three species of Brucella when grown on a culture medium under aerobic conditions, the differences should be measurable in an oxidation-reduction system if the same growth conditions are maintained. The measurement of electrode potentials of culture mediums under aerobic conditions requires the employment of a system in which the potential of the cell will remain at or near the same level for a period before inoculation. The maintenance of electrode potentials at a constant level in liquids containing organic materials has been difficult without the introduction of some dynamic method to prevent the drift of potential and the polarization of the electrode. These troublesome factors may be overcome by deaerating the liquid in the electrode vessel and measuring the changes in electromotive force with a vacuum tube potentiometer or an electrometer.