EFFECT OF ALKYL BENZENE SULPHONATE ON YEAST METABOLISM

Abstract

The rate of fermentation of glucose by suspensions of Candida utilis at acid pH values is reduced by alkyl benzene sulphonate in the range 75 to 250 γ/ml. Concentrations of alkyl benzene sulphonate below 75 γ/ml decrease the rate of fermentation of glucose above pH 7 and respiration at all pH values. An upper limit of 70 to 90% inhibition of fermentation or respiration is obtained at concentrations of alkyl benzene sulphonate above 250 γ/ml, except at pH 4.2 where complete inhibition is obtained. The effect of alkyl benzene sulphonate on the fermentation of glucose by yeast protoplasts is similar to the effect observed for intact yeasts. Some enzymatic reactions of cell-free extracts are inhibited by concentrations of alkyl benzene sulphonate lower than that required to affect fermentation by intact cells. The enzyme components of the cell-free preparation appear to vary in their sensitivity to the surfactant. The results support the view that the surfactant in the micellar form disrupts the cell wall of the yeast, and unassociated molecules inactivate some enzymes vital for the metabolism of the cell.