2.4. Batch and fed-batch fermentations in a 5-L stirred-tank
fermentor
Batch and fed-batch fermentation kinetics was studied in a 5-L
stirred-tank fermentor (Shanghai Baoxing Co., Ltd., China) containing
3 L of media. The fermentation was inoculated with 300 mL
of seed culture grown in a shake flask for 48 h, and operated at
25 ◦C with agitation and aeration at 400–800 rpm and 1.3 vvm,
respectively. During fermentation, the agitation was controled to
maintain the dissolved oxygen level >20%. The exhaust gas was
monitored using a Hartman PS6000 gas analyzer (PS 6000, Hartman,
China) to calculate the carbon dioxide evolution rate (CER)
[17]. For fed-batch fermentation, xylose with a concentration of
approximately 600 g/L was fed into the fermentor when the residual
xylose concentration was