The influence of potassium and sodium ions on the negative Pasteur effect in Brettanomyces claussenii Custers.

Abstract

The present article deals with the “negative Pasteur effect” in Brettanomyces claussenii Custers, i.e. with the inhibition of the alcoholic fermentation under anaerobic conditions and its stimulation in presence of atmospheric oxygen. As distinct from the negative Pasteur effect in resting cells of Saccharomyces species the effect in Br. claussenii is not specific for cell suspensions prepared with succinic acid-succinate buffer but may at Ph 4.5–4.6 in addition be demonstrated in resting cells suspended in distilled water or phosphate buffer as well as in buffer solutions of a great number of organic acids and their alkali salts, e. g. in acetic acid-acetate, propionic acid-propionate, oxalic acid-oxalate, malonic acid-malonate, fumaric acid-fumarate, malic acid-malate, d-tartaric acid-tartrate, and citric acid-citrate mixtures. The aerobic fermentation of glucose by resting cells of Br. claussenii is quite sensitive to potassium and sodium ions. In all systems examined, except the succinic acid-succinate buffer and the buffer solutions inhibiting the fermentation completely or practically completely, the rate of the aerobic fermentation is considerably increased on increasing the concentration of the potassium ions and decreasing that of the sodium ions. Under anaerobic conditions the alcoholic fermentation is insusceptible to the ions mentioned. Because of the fact that the influence of the potassium ions or of the K+/Na+ ratio upon the rate of fermentation is comparatively large under aerobic conditions but small or even negligible under anaerobic conditions, the magnitude of the negative Pasteur effect will under the proper conditions be determined by the potassium ion concentration or by the ratio between the concentrations of the potassium and sodium ions. The negative Pasteur effect obtained in a buffer of an acid and its potassium salt may be considerably larger than that observed in a buffer of the same acid and its sodium salt. In solutions containing a mixture of the potassium and sodium salts in addition to an acid the magnitude of the negative Pasteur effect will increase with increasing potassium ion concentration and decreasing sodium ion concentration at constant total molar concentration of the alkali ions.