Fig. 3.

Production of d-lactate by the two-dose fermentation. The fermentation was conducted with the aerobic growth phase and the fermentative production phase. A high dose of crude glycerol was added to the culture broth at the end of the growth phase. The fermentation was initiated with the cell density at OD₅₅₀ of 1. The absorbance measurement of the cell density in the production phase was interfered with crude glycerol and Ca(OH)₂ and, therefore, not reported. The experiment was duplicated. The typical fermentation profiles were reported for the cases with the DO control (a) and without the DO control (b). Cell density (black circle); crude glycerol (black up-pointing triangle); d-lactate (black square); α-KG (white circle)