利用分開及同步醣化發酵自狼尾草生產生質乙醇之研究

Bioethanol Production from Steam-exploded Naipergrass via Separate Hydrolysis and Fermentation and Simultaneous Saccharification and Fermentation

黃毓芬(Yu-Fen Huang)

指導教授 ： 余碗琴

國立臺北科技大學/工程學院/有機高分子研究所/碩士(2014年)

摘要

狼尾草是一種深具潛力的能源作物，經由酵素水解後，再進行微生物醱酵，可將其轉換為乙醇、琥珀酸等平台化學品。本實驗室先前已針對狼尾草渣建立蒸煮爆碎/鹼性過氧化氫的預處理法，本論文的研究的重點在於預處理後狼尾草的酵素水解及乙醇醱酵條件最適化，所使用的基質濃度為15 wt%，乙醇醱酵菌株為‎Saccharomyces cerevisiae， 探討基質和酵素批次或階段饋料對醣化率的影響，並比較分開水解醱酵(separate hydrolysis and fermentation, SHF)與同步醣化醱酵(simultaneous saccharification and fermentation, SSF)對乙醇生產的影響。研究結果顯示，在酵素水解醣化部份，為兼顧葡萄糖濃度、葡萄糖產率等因素，最適操作參數為酵素批次加入(即於醣化反應起始全部加入)，而狼尾草則分別於0 h、12 h、48 h饋料1/3，經過120 h的反應，葡萄糖濃度與產率分別達76 g/L與 59.7%。在乙醇生產部份，SSF比SHF的表現較為優異，最適操作條件為物料與酵素皆於醱酵起始即批次加入，乙醇濃度達58.6 g/L，而其產率達48.3 %，為理論產率之96.6%。

關鍵字

狼尾草 ； 蒸爆法 ； 酵素水解 ； 階段饋料 ； 乙醇發酵

並列摘要

Napiergrass (Pennisetum purpureuum), regarded as a potential energy crop, can be used as the feed stock for the production of platform chemicals, such as ethanol and succinic acid. Previously, we have established an effective pretreatment procedure for napiergrass, involving steam explosion followed by alkaline hydrogen peroxide delignification. The pretreated napiergrass has a high cellulose content with little lignin. The present work focuses on the enzymatic saccharification of pretreated napiergrass, and its conversion to ethanol via yeast fermentation at a high solid loading of 15 wt%. The enzymatic hydrolysis was conducted with the following enzyme loadings: cellulase 10 FPU/g cellulose and β-glucosidase 20 CBU/ g cellulose, either in a batchwise fashion or in a multi-step fed-batch mode. Best glucose yield was obtained when the cellulolytic enzymes were introduced in a batchwise mode at the beginning of the reaction, while the substrate was fed in a multi-step fashion, where 1/3 of substrate was fed at 0 h, 12 h, and 48 h, respectively. After 120 h of hydrolysis, a glucose concentration of 76 g/L was obtained, corresponding to 59.7% glucan conversion. For ethanol fermentation, the simultaneous saccharification and fermentation (SSF) process outperformed the separate hydrolysis and fermentation process (SHF). The best result was obtained when all the substrate and the enzymes were fed at the start of SSF; fed-batch operation was found unnecessary. After 120 h of SSF, the ethanol concentration and yield reached 58.6 g/L and 48.3 % respectively, corresponding to 96.6% of the theoretical yield.

並列關鍵字

Napiergrass ； steam explosion ； enzymatic hydrolysis ； multi-step-batch ； ethanol production

參考文獻

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