Influence of Certain Dye-Stuffs on Fermentation and Respiration of Yeast Extract

Abstract

An aqueous extract of yeast can be prepared which is free of cells but which will actively ferment glucose to alcohol and CO₂. Such an extract consumes only a small amount of oxygen and this small amount exerts no measurable effect on the rate of fermentation. Consequently the extract exhibits no Pasteur reaction. If, however, a dyestuff, which is reversible with respect to oxidation and reduction and which can be reduced by the extract and oxidized by oxygen, is added to the extract, an appreciable oxygen consumption ensues. According to Lipmann 1 this oxygen consumption may or may not inhibit fermentation. He concludes that the deciding factor is the oxidation-reduction potential which the dyestuff imposes on the fermenting mixture. If the potential range of the dye added is relatively negative no inhibition occurs. If it is relatively more positive and oxygen is supplied at a rate sufficient to keep a part of the dye in the oxidized form, inhibition does occur and, according to his results, may be reversed if the potential is lowered by making the experiment anaerobic and adding a reductant (ascorbic acid) plus diphosphate. He regards this as an example of the Pasteur reaction and considers the mechanism of this reaction to be the reversible oxidation of some component of the fermentation system which is active only in the reduced form. If this explanation of the Pasteur reaction is true, and it seems to have found a ready acceptance by some investigators, 2 , 3 it would have a most important bearing on the fundamental aspects of respiration and fermentation. It seemed to us desirable to try and check this general idea.

The yeast used was a bottom yeast kindly supplied to us by Ruppert's brewery. It was pressed at 800 lb. pressure, dried in the air at 25°C., ground to a fine powder and stored in the ice box.