预处理改变稻草亚细胞结构的化学基础

以氢氧化钠、碳酸氢铵和尿素处理的稻草为研究对象，采用糖腈乙酰酯法和碱性硝基苯氧化法，分别测定了化学预处理前后稻草用80％乙醇浸提残渣中结构性多糖和木质素组分的变化．试验结果显示，化学预处理后稻草结构性多糖水解产物下降7．9％～17．7％；木质素组分中愈伤木基木质素下降31．9％～37．7％，对羟基苯基木质素下降16．6％～28．5％，紫丁香基木质素下降11．5％～16．8％，对香豆酸下降16．6％～26．3％，阿魏酸下降5．5％～11．1％．各组分下降幅度均以氢氧化钠处理最高．上述结果表明，化学预处理通过破坏木质素与结构性多糖、木质素单体之间的连接，导致细胞壁各层的木质素组分不同程度的下降是化学预处理后稻草亚细胞结构变化的化学基础所在．

Study on the chemical basis of chemical pretreatment to change the ultrastructure of rice straw

Aldononitrile acetates and alkaline nitrobenzene oxidations were used to analyze the change of structural polysaccharides and composition of lignin in 80 % ethanol-extracted rice straw treated with sodium hydroxide, ammonium bicarbonate, or urea. After chemical treatments, neutral sugars in ethanol-extracted rice straw were decreased by 7.9% - 17.7 %; guaiacyl, p-hydroxyphenypropane, syringlyl units, p-coumaric acid and ferulic acid in ligninwere decreased by 31.9%-37.7%, 16.6%-28. 5%, 11.5%-16.8%, 16.6%-26.3%, and 5.5%- 11.1 %, respectively. The best decrease was always at sodium hydroxide treatment among these components. These results indicated that chemical treatments may cleavage the linkages between lignin and polysaccharides, and between monomers of lignin, which results in the decrease of compositions of lignin in primary and secondary wall of rice straw, and hence increases the degradation rate of secondary wall and degree of primary wall degradation observed under histological investigation.