以菊芋粉为原料同步糖化发酵生产燃料乙醇

利用粟酒裂殖酵母（Schizosaccharomyces pombe）能发酵菊芋未水解糖液高产乙醇的特点提出了以菊芋粉为原料，同步糖化发酵生产燃料乙醇的新工艺。在摇瓶中考察了原料预处理方法、原料浓度和初始pH值对乙醇发酵的影响，进而在5 L发酵罐中考察了未调控pH值和恒定pH值与通气情况对乙醇发酵的影响。结果表明：该菌株最适pH值为4.0；100目筛分的菊芋粉发酵效果良好，115℃灭菌处理优于121℃，在此条件下，菊芋粉浓度200 g/L时，乙醇产量达到66.58 g/L，理论转化率为85.88%；发酵液pH值下降对乙醇发酵没有影响，通入适量氧气会导致乙醇产量的下降，这表明粟酒裂殖酵母进行乙醇发酵时不需要供氧；通入氮气保持厌氧环境不能显著提高乙醇产量，不通气进行乙醇发酵也达到高的转化率，因此在工业生产中，不必保持厌氧发酵环境。在此基础上，对菊芋粉补料发酵进行了试验，补料至菊芋粉终浓度为300 g/L，发酵终点乙醇浓度为94.81 g/L，理论转化率为81.54%。这些研究工作，为以菊芋为原料的燃料乙醇工业化生产提供技术依据。

Production of ethanol by simultaneous saccharification and fermentation from Jerusalem artichoke flour

Based on the ability of Schizosaccharomyces pombe to ferment inulin-containing extracts into ethanol, the production of fuel ethanol by simultaneous saccharification and fermentation (SSF) using Jerusalem artichoke flour as raw material was presented. The effects of raw material treatment, Jerusalem artichoke flour concentration, initial pH value on the ethanol fermentation performances of Schizosaccharomyces pombe were investigated in a shaking flask, at the same time, the effects of the constant-pH fermentation and the uncontrolled-pH fermentation, aeration rate on the ethanol fermentation were also studied in a 5 L jar fermenter. Experimental results showed that the optimum initial pH value was 4.0, Jerusalem artichoke flour particle size was below 0.15 mm, high temperature treatment at 115℃ for 35 min was better than that at 121℃ for 20 min. According the optimum conditions for producing fuel ethanol, the maximum ethanol yield of 66.58 g/L, equivalent to 85.88% of the theoretical yield, was obtained for the slurry with a solid concentration of 200 g/L at 30℃ after 48 h of incubation in a shaking flask. The decrease of pH value of the broth had little effect on ethanol fermentation. The aerobic condition resulted in lower ethanol yield than strictly anaerobic condition and non-aeration condition. The ethanol concentration was a little difference between strictly anaerobic condition and non-aeration condition. Ethanol production by fed-batch fermentation was investigated and the maximum ethanol concentration of 94.81 g/L, equivalent to 81.54% of its theoretical value, was reached with final Jerusalem artichoke flour of 300 g/L in a 5 L jar fermenter. These results provide a scientific basis for fuel ethanol production from Jerusalem artichoke.