木質素與纖維形態對纖維素內切酶水解桉樹硫酸鹽紙漿之影響

Abstract

本實驗利用紙漿纖維和纖維素間切酶來探討纖維素材料的物理及化學性質對於酵素水解的影響。 材料的部分以PFI磨漿機來製造不同形態的纖維，以不同的氧漂及氯漂漂序來製造含有不同木質素和聚戊醣含量的纖維，來作為不同木化性質的纖維材料。 酵素對於紙漿的可及性，是將纖維及酵素置於4oC及40oC環境下做蛋白質的吸附，除了測定游離蛋白質含量外，也測定分子量和還原糖來觀察纖維的水解程度。 在低溫4oC的蛋白質吸附結果顯示，因在經過PFI磨漿後，產生較短、較寬的纖維，以及較多的微細纖維情況下，對於酵素有較好的吸附可及性，且木質素含量最少者有最高的吸附量；反之，在高溫水解時，較多木質素含量的纖維卻有較高的酵素吸附量。 對於PFI磨漿處理，未經PFI磨漿的纖維在經過酵素水解後，未漂漿的分子量下降最少；但若是經過PFI磨漿後，木質素的存在對於分子量下降多寡的影響便會下降，而讓PFI磨漿處裡的纖維有幾乎相同的分子量降解程度。 實驗結果表示，磨漿處理可以讓纖維表面產生較多的可反應面積，並改善木質素和聚戊糖在酵素水解時所會造成的影響。

Roles played by fiber physical and chemical characteristics in enzymatic hydrolysis of cellulosic materials were investigated by analyzing the interaction between an endoglucanase complex and eucalypt kraft fibers. PFI refining was employed to create the difference of fiber size distribution and morphology. Oxygen delignification and bleaching were employed to prepare fibers with different lignin and pentosan contents. The enzyme accessibility was monitored by adsorption at 4oC and during hydrolysis at 40oC. Molecular weight changes and reducing sugar released were monitored for digestibility of the samples. Greater maximum adsorption capacities of the enzymes were shown for the pulps with shorter and wider fibers and more fine fractions after refining. Highest amount of enzyme was adsorbed onto fibers with the least lignin contents at 4oC. Fewer desorbed from fibers with higher lignin contents during hydrolysis at 40oC. For unrefined fibers, less molecular weight reductions were observed for fibers with higher lignin contents. However, extensive fibrillation by refining negated the effects of lignin on the action of endoglucanase, similar molecular weight reductions were observed for fibers with three different lignin contents. Refining could be able to expose more reaction sites on the fiber surface, hence the impacts of lignin and pentosan diminished during hydrolysis for refined fibers.