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摘要：全球目前面临着环境污染的加剧以及石油危机，越来越多的国家开始利用乙醇作为替代燃料。我国作为农业大国，可以充分利用农作物秸秆发酵生产乙醇，以解决我国的能源问题，然而农作物秸秆生产乙醇由于分解困难而导致产量低但生产成本高，于是我们应该提升产量以减少乙醇的生产费用。本论文旨在通过提高纤文素酶的酶活，将秸秆中的纤文素转化成可发酵性糖。本论文主要是用单因子和正交试验来探讨黑曲霉产纤文素酶受培养基组成及发酵条件的影响，主要从含水量、水稻与豆粉比、温度、发酵天数、pH、硫酸铵、接种量等来探究对纤文素酶酶活的影响。通过实验得出最优培养基的成份和含量：水稻2.4 g，豆粉0.6 g，水70%，硫酸铵4%，磷酸二氢钾0.2%，硫酸镁0.2%，pH 7，接种量5×106。最优的培养条件为：培养温度41℃，发酵天数6天。通过对发酵条件的优化，黑曲霉产纤文素酶的酶活由374.55 U/g提高到851.90 U/g。34672
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毕业论文关键词：纤文素酶、黑曲霉、发酵条件、正交试验
Optimization of cellulase fermentation conditions of rice straw as raw material
Abstract: The world is facing the increasing environmental pollution and oil crisis, More and more countries began using ethanol as a substitute fuel. China is an agricultural country, The energy problem can be solved by ethanol fermentation using crop straw, However, It’s ethanol yield is low and cost is high to produce ethanol using crop straw, So it’s important to improve the yield and reduce production cost. This paper is aimed at improving the activity of cellulose which can transform cellulose to fermentable sugar. This experiment is mainly through single factor and orthogonal experiment to study the effects of medium composition and culture conditions on cellulase production by Aspergillus niger, Mainly on water content, ratio of rice to flour, temperature, fermentation time, pH, ammonium sulfate, inoculation amount effect on the activity of cellulose. In order to obtain the optimal medium recipe: rice 2.4 g, soybean flour 0.6 g, water 70%, 4% (NH4)2SO4, 0.2% KH2PO4, 0.2% MgSO4, pH 7, inoculation 5×106. The optimal culture conditions: culture temperature 41℃, fermented for 6 days. Aspergillus niger cellulase production was increased from 374.89 U/g to 906.67 U/g through the optimization of cellulose fermentation conditions.
Keywords: cellulase, Aspergillus niger, fermentation conditions, orthogonal experiment
目录
引言 1
1.材料和方法 2
1.1材料 2
1.1.1菌种 2
1.1.2培养基 2
1.1.3试剂及配制 2
1.1.4仪器设备 2
1.2实验方法 2
1.2.1菌种复苏 2
1.2.2配制基础产酶培养基 3
1.2.3接种以及固体发酵 3
1.2.4葡萄糖标准曲线的制作 3
1.2.5粗酶液的制取 3
1.2.6酶活力的测定 3
1.2.7酶活力的计算 3
2.结果与分析 4
2.1葡萄糖标准曲线 4
2.2培养基及培养条件的优化结果 4
2.2.1水稻与豆粉比对产纤文素酶的影响 4
2.2.2硫酸铵对产纤文素酶的影响 5
2.2.3接种量对产纤文素酶的影响 6
2.2.4发酵天数对产纤文素酶的影响 6
2.2.5含水量对产纤文素酶的影响 7
2.2.6 pH值对产纤文素酶的影响 8
2.2.7温度对产纤文素酶的影响 8
2.3正交试验优化培养基 9
2.4正交试验结果与分析 9