【作者】 廖浩锋；

【导师】 彭良才； 郝勃；

【作者基本信息】 华中农业大学 ， 作物遗传育种， 2011， 硕士

【摘要】 随着人们对全球气候变暖和能源危机的关注,发展非石油燃料成为社会的普遍认识。纤维乙醇能够减少温室气体的排放并且不会产生“与人争粮”的问题,因此受到广泛的关注。木质纤维素是植物体的主要构成物质,由纤维素、半纤维素、木质素、果胶质等生物高分子所组成。它是生产纤维乙醇的主要原料,而且它自身成分结构特点严重阻碍了生物质的降解转化。本课题通过稀硫酸处理植物秸秆来研究细胞壁成分对生物质降解转化的影响。芒草材料间的纤维素和半纤维素含量差异较大,木质素含量变化相对较小。水稻的材料间纤维素含量差异较小,但是半纤维素、木质素含量差异较大。芒草的三大细胞壁成分含量都比水稻高。在稀酸预处理中,随着H2SO4浓度的提高,芒草和水稻的总糖产率也在提高。芒草的预处理五碳糖产率比水稻高,而水稻的预处理六碳糖产率比芒草高。芒草和水稻材料间的降解差异性不会随着酸浓度的改变而改变。晶体状纤维素、木质素不利于酶解产糖,而半纤维素、酸溶性木质素和糖醛酸有利于酶解产糖。酸碱组合处理结果表明,酶解产糖率高的材料在预处理中相应的五碳糖产率高,即半纤维素易于降解,而酶解产糖率低的材料则相反。电镜观察表明,稀酸处理后秸秆表面比较光洁而且纤维素原纤保存完整。水稻和芒草的精细分析结果表明,酶解产糖率高的材料的纤维素结晶度较低、半纤维素组成单糖中木糖含量较高。在酸和碱处理中材料间的降解差异趋势一致,即酸处理中产糖率高的材料在碱处理中的产糖率也高。更多还原

【Abstract】 Concerns about global climate and energy supply lead to seeking a non-petroleum-based fuels. Use of cellulosic-ethanol offers several benefits towards reduction of the greenhouse gas emissions and preventing of the competition with food supplies.Ligno-cellulosic biomass is a natural complex primarily consisting of three biopolymers:cellulose, hemicelluloses and lignin. Biomass recalcitrance is the largest obstacle to emerging cellulosic ethanol biorefineries. The purpose of this study was to identify Miscanthus and rice cell wall composition that influence the effectiveness with a dilute acid pretreatment process.The results showed that cellulose and hemicelluloses contents were varied among Miscanthus tested samples, with a little change in lignin. Compared to Miscanthus, rice is greatly varied in the hemicellulose and lignin contents. With increasing H2SO4 concentrations, total sugar yields were raised in both Miscanthus and rice. Particularly, pentose released from Miscanthus is more than one in rice, and hexose in rice is more than in Miscanthus’s. Pretreatment by different acid concentrations, the difference of degradation in the Miscanthus and rice were not much changed. Crystalline cellulose and lignin have a negative effect on the enzymatic hydrolysis. The hemicelluloses, acid soluble lignin and uronic acid contents have a positive effect on the enzymatic hydrolysis. The degradation of the combined acid and alkali treatments showed that hemicelluloses are the crucial factors for biomass degradation in Miscanthus. The results of scanning electronic microscopy showed that major microfibrous cellulose structures remain after acid treatment.Materials which have high rate of enzymatic hydrolysis also have a lower degree of crystallinity, and more xylose. The difference of degradation in the Miscanthus and rice by acid was consistent with pretreatment of alkali.更多还原