Abstract
The effect of the oxygen absorption coefficient Kd, which represents the intensity of aeration and agitation, upon the yeast (Saccharomyaes cerevisiae, Fleishmann) growth in the modified WHITE's medium was investigated, by means of the shaking flask and two different types of glass-jar fermentor.
The results obtained are as follows:
1) At the exponential phase of growth, the rate of sugar consumption dS/dt is directly proportional to the rate of growth dm/dt, thus
dS/dt=K dm/dt
where the constant K, is called the “sugar consumption coefficient”
2) As shown in Figures 4 and 5, the growth rate constant r at the value of Kd=1.2×10-6, reaches the maximum and the sugar consumption coefficient K, becomes the minimum (that is, the yield of yeast per sugar reaches the maximum), and no more increase (or decrease) is to be found, even if Kd is increased beyond this range. Therefore, aeration and agitation which are beyond some intensity, have no good influence upon yeast growth, but undoutedly causes a loss of power.
3) There is no difference in the values of r and K corresponding to the same value of Kd, in any case of the shaking culture and tank fermentations examined. This indicate that Kd is the important scale-up factor for the case, when the large scale tank fermentation is success fully put into practice based on the results obtained from the shaking culture.
