不同木質材料及離子溶液處理後對酵素吸附及水解的影響

全球氣候變遷與地球暖化逐漸加劇，近年來生質燃料成為解決環境問題的方法之一，而其最大的來源來自於纖維素，纖維素為自然界分布最廣的聚合物，具有生物可分解性、可再生性等優點。因此對於木質纖維材料的加工例如水解與化學改質的研究是勢在必行的。為了研究木質纖維材料的吸附與水解行為，本研究中使用漂白桉樹硫酸鹽漿(BEK)，未漂桉樹硫酸鹽漿(UEK)及狼尾草蒸氣爆碎漿(SEP)並加上Avicel作為純的纖維素來源。另外本研究中使用的水解酵素包含單一內切酶的Fibercare®商業酵素及還有複合纖維素酶的50013商業酵素。在4˚C低溫吸附實驗中，若使用Fibercare®在逐步提高酵素劑量下BEK表現出最佳的吸附容量；若改以複合酵素的50013則UEK擁有更好的吸附容量。然而在固定劑量下長達2天的吸附實驗中SEP卻表現出最佳的吸附行為，其原因來自於SEP中的木質素也吸附了部分的酵素所致。此外2天的吸附兩種商業酵素表現出的吸附曲線亦不相同：Fibercare®因為內切酶逐漸吸附而呈現出累加的趨勢，50013則因複合配方針對基質上不同活化位置同時吸附而在吸附初期即達最大吸附量。另外在40˚C高溫吸附實驗中無論Fibercare®以及50013皆呈現逐漸增加的吸附曲線，原因為在高溫下由於纖維酵素不斷重複吸附、催化及脫附。此外，以50013水解產生還原糖的測定下，UEK在四種基質中表現出最佳的產率，產率最低的則為Avicel。本實驗亦使用1-丁基-3-甲基咪唑氯化鹽([Bmim]Cl)作為前處理方法，經由前處理後4種基質皆變成膜狀，但是經由X光繞射得知其結晶度並無顯著改變。其中，Avicel的還原糖產率與文獻相符有所提升，但3種漿料卻因為膜狀而影響其酵素可及性使得吸附表現與還原糖產率皆嚴重下降。因此紙漿與離子溶液前處理的關係仍需要更多的測試與探討。

關鍵字

木質纖維素；纖維水解酶；吸附；水解；離子溶液前處理

並列摘要

Biofuels gradually become one of the answer to solve environmental problems, their biggest resource-cellulose is most important natural polymers, inexhaustible, degradable, globally abundant biopolymer available today. Thus further study on lignocellulosic materials bioconversion is needed and inevitable. To investigate the adsorption and hydrolysis behaviors caused by lignocellulosic materials. In this study, bleached eucalyptus Kraft pulp (BEK), unbleached eucalyptus Kraft pulp (UEK) and steam explosion pulp (SEP) plus Avicel as pure cellulose resource were used. Two commercial cellulase were used, which Fibercare® only contains endoglucanase and 50013 is complex component. On 4˚C adsorption, BEK showed best adsorption capacity with Fibercare® under high cellulase dosage among substrates; UEK had better adsorption with 50013. Whereas SEP performed highest adsorption ability as time went on due to lignin trapped parts of cellulase. Fibercare® had an accumulation trend during adsorption but 50013 tends to adsorbed fast initially. On the other hand, 40˚C adsorption showed gradually increased on adsorption when cellulase presented adsorption and desorption constantly. Furthermore, hydrolysis under 40˚C was also tested using 50013 to measure reducing sugar yields, in which UEK had highest conversion rate and Avicel had poorest yield. After [Bmim]Cl pretreatment substrates had become film-shape, in which Avicel reducing sugar yield was improved. However, film-shape of pulps’ accessibility had severely affected that adsorption and reducing sugar yield decreased. Through X-ray diffraction showed that crystallinity index changed limited after pretreatment. Thus further work on ionic liquids to substrate have to be studied.

並列關鍵字

Lignocellulose ； Cellulase ； Adsorption ； Hydrolysis ； Ionic liquids Pretreatment

參考文獻

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不同木質材料及離子溶液處理後對酵素吸附及水解的影響

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