运动发酵单胞菌和休哈塔假丝酵母混合发酵秸秆产乙醇

Ethanol production from corn stover using mixed cultures of Zymomonas mobilis and Candida shehatae

首先考察了运动发酵单胞菌(Zymomonas mobilis,Z.mobilis)和休哈塔假丝酵母(Candida shehatae,C.shehatae)分别利用葡萄糖或木糖为唯一底物时的乙醇发酵特性;其次,研究了单菌及双菌发酵混合糖(葡萄糖和木糖比例为3∶1)的产乙醇性能;在此基础上,考察了单菌和双菌培养应用于玉米秸秆发酵产乙醇的可行性。结果表明,Z.mobilis和C.shehatae的接种方式显著影响混合糖发酵产乙醇的效率,当分步接种发酵48 h后,乙醇产量达到最高,为25.77 g/L。当以60 g/L Na OH预处理的玉米秸秆为底物时,分步接种可高效利用秸秆酶解产物(葡萄糖和木糖)实现乙醇产量的最大值(22.34 g/L),提示Z.mobilis和C.shehatae分步接种发酵可最大化地发酵秸秆中的葡萄糖和木糖生产乙醇,有利于乙醇的高产率生产,可为实现纤维原料生产燃料乙醇的工业化提供参考。

The fermentation of Zymomonas mobilis and Candida shehatae using different concentrations of glucose and xylose were firstly investigated. Then ethanol production performance from glucose, xylose, mixed sugars （glu- cose and xylose） and NaOH-treated corn stover by single strain and mixed cultures of Z. mobilis and C. shehatae were further studied. Results showed that stepwise inoculation of Z. mobilis and C. shehatae significantly affected the ethanol production from mixed sugars. The highest ethanol concentration of 25.77g/L was achieved when Z. mobilis was inoculated firstly and followed by C. shehatae after 24 h fermentation （two-step inoculation）. During simultaneous saccharification and fermentation by the mixed cultures in a 20L fermentor, the highest ethanol concentration of 22.34 g/L was obtained from 60g/L of NaOH-treated corn stover using two-step inoculation of mixed culture with low sugar accumulation. Our results suggested that the two-step inoculation of Z. mobilis and C. shehatae could maximize fer- mentation of glucose and xylose in biomass to produce ethanol and offered a reference for using lignocelluloses as raw materials to produce fuel ethanol.