Abstract:

The effect of ORP regulation on batch fermentation by Kluyveromyces marxianus 1727-5 was investigated using glucose, xylose and glucose/xylose mixture under stress conditions caused by mixture of acetic acid, formic acid, furfural and 5-HMF. Moreover, batch fermentation from corn stalk hydrolysate was further conducted with the optimized ORP control strategy. The experimental results showed that the stress tolerance of cells to multiple inhibitors above was significantly improved together with enhanced cellular metabolic activities involved in both glucose and xylose utilization. For the fermentation from glucose/xylose mixture, the significant improvements were also achieved with respects to xylose utilization under ORP control conditions. Especially, with ORP controlled at -150 mV, the glucose fermentation time was shortened about 30% with the same ethanol. The yields of xylitol was increased from 3 g·L^-1 to 10 g·L^-1 compared to the control without ORP regulation. More important, when the ORP controlled at -100 mV, fermentation from corn stalk hydrolysate was greatly facilitated in terms of inhibitors tolerance, and the glucose fermentation time was shortened about 22% with the same ethanol. More important, xylose utilization and xylitol yield were increased to 10.27 g·L^-1 and 0.48 g·g^-1, respectively, compared to those of 4.88 g·L^-1 and 0.20 g·g^-1 in the control without ORP regulation.

Key words: aeration, ORP, lignocellulose, inhibitor, fermentation

摘要：

采用通气的方式进行氧化还原电位（oxidation-reduction potential，ORP）调控，研究在添加抑制物条件下Kluyveromyces marxianus 1727-5利用葡萄糖、木糖以及两者混合体系的发酵性能，在此基础上考察了ORP调控策略对玉米秸秆水解液发酵的影响。研究结果表明：在调控ORP策略下，多种混合抑制物对酵母生长代谢造成的损害得以有效改善，细胞活性高，木糖、葡萄糖代谢速率加快。葡萄糖与木糖共发酵时，ORP调控至-150 mV时，葡萄糖发酵时间缩短近30%，木糖醇浓度由3 g·L^-1增加到10 g·L^-1。ORP调控策略也同样能有效缓解玉米秸秆水解液中较高浓度的多种抑制物对酵母细胞的胁迫，ORP为-100 mV时，相比于对照组，在保持终点乙醇不变的情况下，葡萄糖的发酵时间缩短了22%；木糖消耗由4.88 g·L^-1增至10.27 g·L^-1，木糖醇得率也由0.20 g·g^-1提高至0.48 g·g^-1。

关键词: 通气, 氧化还原电位, 木质纤维素, 抑制物, 发酵