Abstract
Distillers' yeast requires both biotin and pantothenic acid as essential growth factors and thiamine as a growth stimulant as shown in the preceding paper. However thiamine exerts a significant inhibitory action on the yeast growth and consequently alcohol production, when it is added to the medium which contains one of the two essential vitamins in enough amount and the other only in small quantity. The inhibitory effect is observed more clearly in the case of biotin deficiency. In the presence of enough amount of biotin, the optimal ratio of pantothenic acid to thiamine for alcoholic fermentation is 2 : 1 to 1 : 1. From these results it is considered that well balancing of the vitamins is important for an alcoholic fermentation in yeast.
