Исследование влияния интенсивности аэрации на жизнедеятельность дрожжей Brettanomyces bruxellensis

Abstract

This research is aimed at investigating the effects of aeration on the cell growth of the Brettanomyces bruxellensis yeast and its production of acetic acid and ethanol. Experiments were carried out in a glucose medium and with an air supply of 0-300 dm 3 /h. It is established that the growth of the biomass is stimulated by a moderate aeration, with the optimal value of the airflow rate being 60 dm 3 /h. When this value is exceeded, the concentration of the cellular biomass decreases. The yield of ethanol and acetic acid is shown to be dependent on the level of aeration: the greater the volume of air supplied to the fermenter, the higher the yield of acetic acid, and the lower the yield of ethanol. Under a high intensity of aeration, a significant decrease in the ethanol yield is observed. An aeration intensity of above 180 dm 3 /h results in a decline in the glucose consumption by yeast cells and an increase in the acetic acid concentration in the culture medium (6,0 g/dm 3 ). The ethanol + acetic acid ratio produced per mole of utilized glucose was analysed according to the mass balance of the reaction. The ethanol + acetic acid ratio is shown to remain unchanged under the given conditions. This allows the stoichiometric equation of the fermentation reaction to be clarified for the calculation of the optimal value of oxygen supply and the yield of main products.