预处理过程产生的抑制剂对纤维素酶酶解效率的影响

Effect of Inhibitors Produced by Pretreatment Lignocellulosic Materials on Cellulase Enzymatic Efficiency

在木质纤维产乙醇研究中,原料在稀磷酸浸渍+蒸汽爆破预处理过程中容易产生糠醛、5-羟甲基糠醛、对苯二酚和间苯二酚等抑制剂,这些抑制剂会影响纤维素酶酶解效率,导致还原糖浓度下降从而影响乙醇生产。通过单因素实验和正交实验,确定了纤维素酶酶解的最优条件为:酶解温度50℃、酶液载入量30 U/mL、酶解固液比1∶11、酶解pH值4.8;选取预处理过程中产生的上述4种抑制剂,测定其浓度分别为:糠醛0.031 g/L、5-羟甲基糠醛0.029 g/L、对苯二酚1.51 g/L、间苯二酚1.242 g/L,探讨上述抑制剂单独或复配后对纤维素酶酶解效率的影响。结果表明,预处理过程中产生的酚类抑制剂高于醛类,在酶解过程中酚类抑制剂对酶解产生的影响高于醛类抑制剂;多种抑制剂的协同作用对酶解的影响高于单一种类抑制剂对酶解的影响;酶解液中抑制剂对酶解的影响强度按对苯二酚、间苯二酚、5-羟甲基糠醛、糠醛依次减弱。

In the study of ethanol production from lignocellulosic materials,the raw materials are prone to produce inhibitors such as furfural,5-hydroxymethylfurfural,hydroquinone,and resorcinol during the pretreatment process of dilute phosphoric acid impregnation and steam explosion.These inhibitors will affect the cellulase enzymatic hydrolysis efficiency resulting to a reduction of reducing sugar concentration and ethanol production.Through single-factor experiments,the optimal enzymatic conditions for cellulase enzymatic hydrolysis were determined as enzymatic hydrolysis temperature of 50℃,enzymatic solution dosage of 30 U/mL,solid-liquid ratio of the enzymatic hydrolysis system of 1∶11,and pH value of enzymatic hydrolysis system of 4.8.The contents of above four kinds of inhibitors produced during the pretreatment process were determined,which were 0.031 g/L for furfural,0.029 g/L for 5-hydroxymethylfurfural,1.51 g/L for hydroquinone,and Hydroquinone 1.242 g/L.The effect of the above inhibitors alone or in combination on the enzymatic hydrolysis efficiency of cellulose was expolred.The results showed that the phenolic inhibitors produced during the pretreatment process were more than the aldehydes,and the influence of the phenolic inhibitors on the enzymatic hydrolysis was higher than the aldehyde inhibitors during the enzymatic hydrolysis.The synergistic effect of multiple inhibitors on the degradation rate of cellulose was higher than the effect of a single inhibitor.The influence intensity of the inhibitors on enzymolysis in the enzymatic hydrolysis solution from strong to weak was in order of hydroquinone,resorcinol,and 5-hydroxymethylfurfural,and furfural.