Factors Affecting Oxidation-Reduction Potentials Produced by Bacteria in Synthetic Media

Abstract

Measurements of the apparent oxidation-reduction potentials established in a synthetic medium by the growth of Escherichia coli showed that many irregularities were encountered which were not present when determinations were made in peptone nutrient broth cultures of the same organism. It is the object of this paper to present a study of the factors involved in these irregularities. The elimination of such would make it possible to obtain consistent data from which valuable conclusions might be deduced.A vacuum tube null-point instrument drawing a maximum current of 10-11 ampere was utilized in making the physical measurements. No polarization phenomena were observed and the apparatus gave calculated values for easily polarizable half cells. Bright platinum electrodes were used. A liquid medium made by weighing the requisite C.P. or analytical reagents and adding to redistilled water allowed the test organism, Escherichia coli, to grow vigorously. This basic solution, a slight modification of that of Kose...