Citric acid production by Candida tropicalis under high dissolved oxygen concentrations

The authors have examined the effect of the DO concentration on the citrate production by Candida tropicalis OT-1, concentrating upon experiments at DO concentrations higher than 40 ppm, by using a 2.6 liters pressure-proof laboratory fermentor. It is notable that the accumulation of citrate increases with an increase in DO concentration up to around 60 ppm and decreases rapidly when DO exceeds this level. In contrast, the accumulation of isocitrate decreases with an increase in DO concentration and becomes negligible at around 50 ppm. The total amount of citrates (citrate and isocitrate) remains nearly constant (about 30 g/liter), being independent of the DO concentration.