碱处理对甜高粱秸秆渣组成结构及酶解糖化效果的影响

Effects of Alkali Treatment on Component and Structure and Enzyme Saccharifying Efficiency of Sweet Sorghum Bagasse

以甜高粱品种M81为试验材料,以清洗烘干后未经处理的甜高粱渣为对照,在常温、高温高压、微波条件下Ca(OH)2和常温条件下NaOH处理甜高粱秸秆渣,调查处理后甜高粱秸秆渣木质纤维素组成结构及纤维素酶酶解糖化情况。结果表明,采用的4种处理都能有效地改变甜高粱渣木质纤维素组成结构,其中氢氧化钠常温长时间处理对于木质素与半纤维素的溶降效果最好,3种石灰处理对半纤维素的溶解也均有一定作用。扫描电镜观察石灰高温高压与氢氧化钠常温两种处理对于木质纤维素结构的改变不同,前者木质纤维素表层木质素结构被侵蚀严重,呈破碎状附着在纤维素表面,内部纤维结构仍紧密排列,后者木质纤维素束状结构溶胀降解,表层木质素成分被大量去除,被包裹的纤维素组分显露,纤维素网断裂且纤维素表面出现许多小孔。经这4种方式处理后的甜高粱渣,木质纤维素中纤维素与半纤维素经纤维素酶酶解糖化,葡萄糖和木糖产物浓度都有所提高,分别达到对照的1.5、2.1、1.9、4.2倍和3.1、5.0、4.9、2.4倍;木质纤维素纤维组分的直接转化率与相对转化率的含义与计算方法不同,两种计算方式对于甜高粱木质纤维素生物质原料预处理方式的选择和效果的综合评价具有指导意义。

Sweet sorghum variety M81 was used as the experimental material, the sweet sorghum bagasse （SSB） was treated un-der four conditions （lime at room temperature, lime with microwave treatment, lime with autoclave treatment and sodium hy-droxide at room temperature） with the washed and untreated SSB as control. The changes of lignocellulose structure and the cel-lulase saccharifying efficiency of SSB under different conditions were investigated. The results showed that four treatments effec-tively changed the lignocellulose component of sweet sorghum bagasse, especially in the case pretreated by sodium hydroxide under room temperature for two weeks, and lime played an important role in hemicellulose dissolution too. Scanning electron microscopy （SEM） observation indicated that the lignocellulose structure was different in two treatments of lime with autoclave treatment and sodium hydroxide at room temperature. The surface of lignin in the treatment of lime and autoclave was eroded seriously and its fragments adhered to the surface of cellulose, but the internal fiber structure still arranged tightly;in the treatment of NaOH at room temperature the lignocellulose beam structure was swelled and degraded, and the cellulose fiber net appeared due to the surface component of lignin removed a lot and many small holes appeared. By using the four pretreated methods, the cellulose and hemicellulose of sweet sorghum bagasse were enzymatically saccharified, the concentrations of glucose and xylose increased 1.5, 2.1, 1.9, 4.2 times and 3.1, 5.0, 4.9, 2.4 times, respectively as compared with the control. The direct conversion rate and the relative conversion rate of cellulose and hemicellulose are different, but have a significant guiding function for the choose of treatment methods and the effect of comprehensive evaluation, in addition, also an instructive function for the breeding and cultivating of sweet sorghum with high yield and good energy productive factors in the practical production.