【作者】 蒋兴；

【导师】 夏黎明；

【作者基本信息】 浙江大学 ， 生物化工， 2013， 硕士

【摘要】 2,3-丁二醇是一种重要的平台化工产品,广泛应用于化工、食品、燃料等领域。本文选择了Klebsiella oxytoca ZU-03为菌株,以廉价的植物纤维废弃物玉米芯为原料,采用同步糖化发酵(SSF)技术生产2,3-丁二醇,并对2,3-丁二醇的提取工艺进行了探索性研究。为了优化SSF工艺,对纤维素酶用量、纤维二糖酶用量、木聚糖酶用量、pH、温度和底物浓度等对2,3-丁二醇形成的影响进行了研究,试验结果表明：在SSF工艺中,每克底物(玉米芯)的酶用量为：纤维素酶25FPIU、纤维二糖酶15IU、木聚糖酶300IU；玉米芯SSF的适宜温度为36℃,pH6.0。当底物浓度为120g/L,同步糖化发酵36h,2,3-丁二醇的质量浓度可达46.03g/L,产率为1.28g/(Lh),转化率为0.424g/g(总糖)。采用分批补料技术,可以提高发酵液中2,3-丁二醇的浓度,降低提取成本。研究了补料时间、补料量以及玉米芯与玉米浆粉的补加比例等对SSF过程的影响,确立了适宜的分批补料工艺：自接种后12h起,每隔12h补一次料,每次补料量为15g/L,补加玉米芯与玉米浆粉的适宜比例为10：2。按照此工艺底物初始浓度为100g/L,补加到底物总浓度为250g/L时,同步糖化发酵144h,2,3-丁二醇的浓度可达75.65g/L。与分批SSF工艺相比,每克底物的酶制剂用量减少了60%。发酵液经FeCl3絮凝处理、固液分离后,采用柠檬酸钠／乙醇双水相体系进行分离提取。考察了柠檬酸钠质量分数、乙醇质量分数和温度对2,3-丁二醇回收率的影响。在单因素试验的基础上,采用了响应面分析对双水相体系分离2,3-丁二醇的条件进行了优化,选用柠檬酸钠质量分数、乙醇质量分数和温度3个因素进行Box-Benhnken中心组合试验设计,对试验结果进行了响应面分析,得出适宜的工艺条件为：柠檬酸钠质量分数为21%,乙醇质量分数为25%,温度为38℃。在此条件下,2,3-丁二醇的回收率为91.8%。发酵液经过絮凝和双水相萃取之后,蛋白去除率为90.6%。利用可再生植物纤维原料替代粮食发酵生产2,3-丁二醇具有重要的经济和社会意义。更多还原

【Abstract】 2,3-butanediol is widely used in chemical, food, fuel and other fields. The production of2,3-butanediol by Klebsilla oxytoca ZU-03under simultaneous saccharification and fermentation(SSF) process from corncob were studied in this paper.Outstanding factors during the SSF process such as the dosage of enzymes, pH, temperature and substrate concentration was optimized for better2,3-butanediol production.The suitable condition was as followed:(for1gramme corncob) cellulase25FPIU,cellobiolase15IU,xylanase300IU, pH6.0,36℃.And when the initial substrate concentration was120g/L, through a36h SSF process,2,3-butanediol turned out to reach46.03g/L with a1.28g/(L·h) productivity and a conversion rate for0.424g/g.Fed batch fermentation method which was frequently used for increasing the final product concentration and lower the followed extracting cost was also discussed here as for the proper supplementation and substrate concentration. It was proved the best that when the substrate corncob to corn liquor was at the rate10:2and15g/L of that was added to batch fermentation every12hours after incubation. After the starting100g/L substrate was supplemented to250g/L and a144h SSF process, the finial2,3-butanediol reached75.65g/L, which possessed a60%enzyme reduction for every1gramme substrate as compared with the traditional SSF technique.After fermentation the broth was carried out a FeCl3flocculation for solid-liquid separation and a further sodium citrate/ethanol two-phase system downstream extraction. On the basis of single-factor test, the separation process was optimized by the response surface analysis, and three key factors-fhe mass fraction of sodium citrate and ethanol, temperature were selected to do Box-Benhnken central composite tests. Through the response surface analysis, the result was that:91.8%2,3-butanediol could be extracted when the mass fraction of sodium citrate and ethanol respectively21%and25%at38℃, and90.6%protein in the broth was removed.Production of2,3-butanediol from renewable plant fiber instead of food has important economic and social significance.更多还原