Kinetic Studies on Yeast Growth (part 5)

Relation between Ethanol Concentration and Cell Yield

Abstract

Yield coefficient of a Shôchû yeast was measured for batch culture in a synthetic medium containing various concentration of ethanol.
The yield coefficient was found to be dependent on the ethanol concentration in the culture medium.
The correlation was formulated as follows
Y_X/S=μ₀/σ₀^ek'P(1-kP)
Where, μ₀ is the specific growth rate at P=0, σ₀ is the specific glucose consumption rate at P=0 and k and k' are the constants.
From the above equation, existence of a maximum growth yield (Y_X/S) _max can be suggested. Referring to the values of the constants, it was expected that the maximum cell yield would have the value of 0.198 (O. D./mg-glucose) when the ethanol concentration is 21.2g/l;
P=(k'-k/kk')=0.022-0.015/0.022×0.015=21.2g/l