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题名	纤维素酶解特性与纤维素同步糖化发酵酒精的研究
作者	周晓宏
学位类别	博士
答辩日期	2003
授予单位	中国科学院过程工程研究所
授予地点	中国科学院过程工程研究所
导师	李佐虎
关键词	纤维素 纤维素酶 同步糖化发酵 固态发酵 酒精
其他题名	Cellulose Enzymatic Hydrolysis and Its Conversion to Ethanol by Simultaneous Saccharification and Fermentation
学位专业	生物化工
中文摘要	纤维素酶解特性是纤维素转化酒精的基础。本文对纤维素酶酶学特性、纤维素酶解动力学、纤维素酶固态发酵过程以及纤维素同步糖化发酵酒精工艺进行了研究。系统研究了两种具有代表性的纤维素酶（T.viride纤维素酶和P.decumbens纤维素酶）的酶学特性特别是纤维素酒精转化条件对这两种纤维素酶的影响。发现T.vilide纤维素酶的滤纸酶活（F队）比例高、β-葡萄糖营酶酶活比例低，而P.decumbens纤维素酶的 FPA比例低，日一葡萄糖普酶酶活比例高，两者可配合使用；酒精对这两种纤维素酶的酶解糖化有可逆性抑制作用；1％的酒精P.decumbens β-葡萄糖营酶有微弱的抑制作用，而3一9％的酒精则对其有促进作用；酵母对这两种纤维素酶的酶活没有明显的影响。 梭甲基纤维素（CMC）的酶解动力学研究结果表明，酶解初速率与底物浓度的关系符合米氏方程。微晶纤维素的酶解动力学研究结果表明纤维素酶吸附符合Langmuir方程，酶解反应速率与纤维素酶的吸附量不呈正比；结晶纤维素与可溶性纤维素的酶解历程可能是相同的吸附一酶解过程。可溶性纤维素的酶解速率大于结晶纤维素的酶解速率。对不同纤维素原料进行了纤维素酶固态发酵的研究，证明了汽爆除增加了木质纤维素的可及性之外，还产生了微生物易于利用的可溶性糖，提高了产酶微生物的菌体生长，从而提高了纤维素酶的产酶水平。同时发现在纤维素酶固态发酵过程中，半纤维素与纤维素都很难降解；半纤维素酶、纤维素酶的酶活力与半纤维素、纤维素的降解不完全正相关，纤维素酶固态发酵过程实际上是同步糖化发酵过程。系统研究了纤维素同步糖化发酵酒精工艺。结果表明，以纸浆为原料酒精得率较高：半纤维素的存在有利于纤维素的同步糖化发酵，但酵母不能利用的半纤维素酶解产物对同步糖化发酵有抑制作用。去除木质素，保留半纤维素有利于提高纤维素同步糖化发酵酒精的速率。并通过环境扫描电镜观察了纸浆纤维在同步糖化发酵过程中的形态变化。补料一分批同步糖化发酵酒精浓度可达4.37％（w/v），高于分批同步糖化发酵酒精浓度（3.17％）37.9％。
英文摘要	Understanding of cellulase properties is the key to bioconversion of cellulose to ethanol. In this thesis, cellulase properties, kenetics of cellulose enzymatic hydrolysis, cellulase solid state fermentation and cellulose conversion to ethanol by simultaneous saccharification and fermentation (SSF) were studied. Properties of two typical cellulases, T. viride cellulase and P. decumhens cellulase, were studied. T. viride cellulase has high portion of filter paper activity (FPA) and low portion of P -glucosidase activity while P. decumbens cellulase has low portion of filter paper activity and high portion of P -glucosidase activity, thus the enzymatic hydrolysis efficiency can be improved by mixing the two celllases in proper proportion. Ethanol has reversible inhibition on cellulose enzymatic saccharification by the two cellulases. 1% ethanol has slight inhibition on P. decumbens J3 -glucosidase while 3-9% ethanol has stimulation on it. Yeast has no impacts on the two cellulases. The initial enzymatic hydrolysis rate of carboxymethyl cellulose (CMC) vs cellulase concentration follows Michaelis-Menten eaqution. The adsorption of cellulase on microcrystalline cellulose follows Langmuir equation and the enzymatic hydrolysis rate is not proportional to the amount of cellulase adsorbed. The modes of enzymatic hydrolysis of crystalline cellulose and soluble cellulose are same, and adsorption might be also needed for enzymatic hydrolysis of soluble cellulose. The enzymatic hydrolysis rate for soluble cellulose is higher than that for crystalline cellulose. Cellulase was solid state fermented by various cellulosic substrates. Steam explosion of wheat straw raises cellulase yields by forming soluble sugar from hemicellulose as well as increasing the accessibility of cellulose, and the soluble sugar is easily adsorbed by the cellulase producing microbe and increases the growth of the microbe. The process of cellulase solid state fermentation is a simultaneous saccharification and fermentation process, in which hemicellulose degrades as slow as cellulose, and the degradation rate of cellulose and hemicellulose is not proportional to cellulase and hemicellulase activities. The technology for converting cellulose to ethanol by SSF was systematically researched. Highest ethanol yield was obtained by using alkaline wheat straw pulp as substrate. Hemicellulose is necessary for the SSF, however, its unfermentable hydrolysates may also inhibit SSF. Pretreatment removing lignin and retaining hemicellulose could increase ethanol yield. The morphological variation of pulp was observed by environmental scanning electron microscope. As much as 4.37% (w/v) ethanol was achieved by fed-batch SSF, which is 37.9% more than the concentration in batch SSF.
语种	中文
公开日期	2013-09-16
页码	131
内容类型	学位论文
源URL	[http://ir.ipe.ac.cn/handle/122111/1417]
专题	过程工程研究所_研究所（批量导入）
推荐引用方式 GB/T 7714	周晓宏. 纤维素酶解特性与纤维素同步糖化发酵酒精的研究[D]. 中国科学院过程工程研究所. 中国科学院过程工程研究所. 2003.

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