Fig. 3

Ethanol fermentation of E. coli B0013-2021HPA from corncob hydrolysate in a 7-l bioreactor. Pre-cultured cells of B0013-2021HPA (a) were inoculated into 3 l of modified M9 medium supplemented with 300 ml of corncob hydrolysate. Using a “two-phase-two-temperature” strategy as mentioned in “Methods”, cell growth phase was controlled at 34 °C under aerobic conditions and ethanol fermentation was conducted at 42 °C under oxygen-limited conditions. As for B0013-1031HPA (b), temperature was set at 37 °C, its optimal temperature, for the two phases. Solid circle: glucose; solid triangle: galactose; solid diamond: arabinose; solid square: xylose; triangle: ethanol; circle: cell mass; dotted arrow: temperature switching point (from 34 to 42 °C), 45 min ahead of transition to oxygen-limited condition; arrow: time point of addition of 300 ml of the corncob hydrolysate