醋酸预水解对稻草化学成分及酶水解性能的影响

研究了醋酸预处理对稻草主要化学成分及酶水解糖化效率的影响。在160℃下以不同的醋酸用量(0～4%)对稻草进行处理,预处理后稻草的Klason木质素含量基本保持不变,约60%的酸溶木质素被脱除;灰分含量(质量分数)约下降30%,灰分中SiO2则几乎全部保留在预处理浆料中。预处理醋酸用量的增加对酸溶木质素和灰分含量的变化均无显著影响。预处理后高聚糖的降解程度随醋酸用量的增加而上升,其中半纤维素的降解程度尤为显著,阿拉伯聚糖、半乳聚糖大量溶出。对经醋酸预处理稻草的酶水解研究表明,预处理中醋酸用量的增加无助于酶水解液中还原糖得率的提高。稻草于160℃下经不添加醋酸的自水解预处理后,其酶解还原糖得率均高于经醋酸预处理的稻草,当纤维素酶用量为40 FPU/g(对底物)时,稻草中高聚糖的酶水解转化效率最高,葡聚糖、木聚糖的转化率分别为67.8%和45.3%,总糖转化率为58.8%。

Effects of Acetic Acid Pre-hydrolysis on the Chemical Compositions and Enzymatic Hydrolysis of Rice Straw

The effects of acetic acid （HAt） pretreatment on the chemical compositions and enzymatic hydrolysis of rice straw were investigated. The contents of Klason lignin and SiOz are little removed when acetic acid is increased from 0 to 4% at 160℃. The acid soluble lignin and the ash content are not obviously affected by the dosage of acetic acid. About 60% acid soluble lignin and 30% ash dissolve during HAc pretreatment. The degradation of polysaccharides, especially hemicellulose goes up in step with the dosage of acetic acid. The result of enzymatic hydrolysis indicates that the increase of acetic acid in pretreatment does not help improving the sugar recovery of rice straw. The effect of auto-hydrolysis on enzymatic saccharification is better than that of acetic acid pretreatment under the same temperature. Auto-hydrolysis pretreatment of rice straw obtains the maximum of final sugar recovery with a cellulase loading of 40 FPU/g substrate, which are 67.8%, 45.3% and 58.8% respectively for glucan, xylan and total sugar.