氧化还原电位控制下自絮凝酵母高浓度乙醇发酵

控制自絮凝酵母高浓度乙醇发酵过程的氧化还原电位（oxidoreduction potential, ORP）能降低环境胁迫对细胞的影响，提高乙醇生产强度和乙醇收率。实验考察了初始糖浓度为200、250、300 g·L^-1及ORP控制为-100、-150 mV和不控制的乙醇发酵情况。结果表明控制ORP的发酵过程，生物量和细胞存活率均高于不控制的系统，相应的发酵速度得到了提高，但是乙醇对糖的收率存在最优值。在实验设定初始糖浓度最高的300 g·L^-1的发酵过程中，控制ORP为-150 mV时，取得了最大的净乙醇生成量和乙醇对糖的收率。ORP控制改变了絮凝颗粒的粒径分布，运用多元线性拟合，发现ORP对絮凝的影响是正向的。ORP改变了发酵液中生物量及代谢物的浓度而间接影响了细胞的絮凝状况。

ORP control on very high gravity ethanol fermentation by flocculating yeast

Very high gravity(VHG)fermentation and using self-flocculating yeast are both advanced technologies to reduce the energy cost in fuel ethanol industry.Oxidoreduction potential(ORP)reflecting yeast momentary physiological status can be regulated for improving cell performance under severe stresses in VHG condition.Batch fermentations with initial glucose concentrations of 200 g·L-1,250 g·L-1 and 300 g·L-1,ORP setting values of-100 mV,-150 mV and no control,were undertaken to evaluate the effects of ORP and initial glucose on ethanol production.It was shown that biomass and viability under ORP control were higher than no control,which resulted in higher net ethanol accumulation and productivity.Moreover,since absence and excess of oxygen supply decreased yield,the best ORP level was found at-150 mV in 300 g·L-1 initial glucose fermentation.ORP control had influence on flocculation as well.By using a multiple variables linear fitting approach,ORP seemed to have a positive correlation with size distribution though its effect is not direct.