碳酸钠预处理对麦草酶水解及木质素结构的影响  

Effects of sodium carbonate pretreatment on enzymatic hydrolysis and lignin structure of wheat straw

作　　者：姜波[1] 曹婷月 谷峰[1] 金永灿[1] 

机构地区：[1]南京林业大学,江苏省制浆造纸科学与技术重点实验室,江苏南京210037

出　　处：《南京林业大学学报（自然科学版）》2016年第6期135-140,共6页Journal of Nanjing Forestry University：Natural Sciences Edition

基　　金：国家自然科学基金项目(31370571);高等学校博士学科点专项科研基金项目(20133204110006);江苏省自然科学基金项目(BK20141473);江苏高校优势学科建设工程资助项目(PAPD)

摘　　要：麦草原料茎秆和叶子的形态构造与化学组成的差异影响其碳水化合物的酶水解转化效率。研究比较了碳酸钠预处理对麦草茎秆和叶子的组分构成及酶水解转化效率的影响,并用化学降解方法分析了预处理后茎秆和叶子木质素结构变化。结果表明:麦草叶子在碳酸钠预处理下具有较好的脱木质素选择性,叶子经以原料绝干重为基准的碳酸钠(质量分数8%)、温度140℃预处理,在10μmol/(min·g)酶用量下的总糖转化率比茎秆高29%。碱性硝基苯氧化和臭氧降降解研究表明,叶子与茎秆木质素存在显著的结构差异,其紫丁香基结构单元和β-O-4连接键含量均较低。碳酸钠预处理后,叶子木质素的碱性硝基苯氧化和臭氧解产物得率的降幅高于茎秆木质素,表明叶子在预处理过程中有更多的β-O-4键发生断裂。由此可以推断,碳酸钠预处理麦草茎秆和叶子的酶水解转化效率与其木质素结构差异存在一定关系,木质素含量及结构是影响木质纤维原料酶水解的重要因素之一。The morphological structure and chemical composition of wheat straw stems and leaves can significantly affect the enzymatic conversion of the carbohydrate. This paper investigated the effect of sodium carbonate （SC） pretreatment on the structural components and substrate enzymatic digestibility （SED） of wheat straw stems and leaves. Structures of stem and leaf lignin before and after SC pretreatment were characterized by wet chemistry methods. Compared with stems, wheat straw leaves showed better delignification effect in the SC pretreatment. The SED of SC-pretreated leaves （TTA content of 8%, 140 ℃ ） reached 80.5% when hydrolyzed at an enzyme loading of 10 μmol/（ min· g）, which was 29% higher than that of stems. The results from nitrobenzene oxidation （NBO） and ozonation indicated that the structure of leaf lignin was different from that of the stem with respect to smaller syringyl units and less β-O-4 linkages. After the SC pretreatment, the reduction of the product yield in the NBO and ozonation of leaf lignin were higher than those of stem lignin, showing that more β-O-4 bonds in leaf lignin were cleaved in the pretreatment. It could be deduced that the different SED between wheat straw leaves and stems correlated with the lignin structure to some degrees. It was confirmed that the content and structure of lignin are important factors affecting the enzymatic saccharification of lignocellulosic biomasses.

关 键 词：碳酸钠预处理 木质素 酶水解转化率(SED) 麦草 茎秆 叶子 

分 类 号：TQ352.62[化学工程]