Redox potential changes in the 2‐keto‐L‐gulonic acid fermentation—I. Correlation between redox potential and dissolved‐oxygen concentration

Abstract

AbstractThe redox potential changes in the oxidative fermentation of L‐sorbose to 2‐keto‐L‐gulonic acid were investigated, using a mutant strain of Pseudomonas. The growth medium contained sorbose as the sole carbohydrate source. It was found that the redox potential curve of the fermenting system indicated qualitatively the existing oxygen demand of the culture. Increasing aeration rates led to higher oxygen demand and lower redox potentials. A comparison of the redox potential curves revealed that although the amount of dissolved oxygen directly affected the respiration of the culture, it did not necessarily mean respiratory insufficiency. The redox potential difference between the aerated and the deoxygenated (nitrogen flushed) fermentation broth was found to be linearly proportional to the logarithm of the dissolved‐oxygen concentration. This observation served as the basis of a new quantitative method of dissolved‐oxygen measurement, for which the name differential redoxymetry was proposed.