低pH值处理技术在树干毕赤酵母酒精连续发酵中的应用

目的]解决连续发酵中杂菌污染的问题。方法]树干毕赤酵母（Pichia stipitis）二级连续发酵戊糖己糖时采用低pH值处理技术来抑制杂菌。结果]采用低pH值处理技术后,以15 g/L木糖和30 g/L葡萄糖混合物为发酵底物,发酵温度（35±1）℃,底物流加速度30 ml/h,二级连续发酵液中酒精平均浓度为15.22 g/L,还原糖利用为95.66%。该系统在连续发酵22 d的运行中从未发现染菌现象,发酵操作相当稳定。结论]树干毕赤酵母对低pH值处理有良好的驯化适应性,pH值为2.40~3.60的处理条件对树干毕赤酵母完全可行。

Ethanol Continuous Fermentation by Pichia stipitis with the Low-pH Value Treatment

Objective] The aim is to solve the problems in the process of the Pichia stipitis fermentation contaminated by other bacterium.Method] The technique of low-pH value treatment in the continuous fermentation process of xylose/glucose through the Pichia stipitis was adopted in order to inhibit other bacterium.Result] After low-pH value treatment,the mixture of the xylose of 15 g/L and the glucose of 30 g/L being taken as substitute,the fermentation temperature of(35±1)℃article studied the low-pH value treatment and the contaminating germ of continuous fermentation of xylose/glucose mixtures by P.stipitis.The adaptability of P.stipitis to low-pH value treatment was so strive that it was able to endure treatments at pH 2.40-3.60.Mixtures of 15.0 g/L xylose and 30.0 g/L glucose as substitute of lignocellulosic hydrolyzates,were used as main fermentation substrate.Tow-stage continuous cultures were carried out in a two-reactor system under condition of temperature of(35±1)℃ and a ventilated rate of 100-150 ml/min.The working volume of single reactor was 1.5 L.When the influent speed was at 30 ml/h or so,the average ethanol concentration in the effluent was 15.22 g/L,and the consumption ratio of substrate was 95.66%.The system was run steadily and no contamination was found during a 22-day′s operation.Conclusion] The P.stipitis has good adaptability to low-pH value treatment and its fermentation could be continual under the pH value of 2.40-3.60.