利用二氧化矽氣凝膠固定化酵母菌Saccharomyces cerevisiae

酵素 (enzyme) 具有可重複使用之特性，但因酵素的水溶性性質，造成回收上的困難，因此現今著重於酵素固定化 (immobilized) 的技術，而酵素本身的價格較昂貴，且在萃取過程中容易降低酵素的活性，因此除了酵素的固定化之外，本研究亦將此固定化技術應用於全活細胞固定化。本研究所採用的固定化法，乃使用溶膠-凝膠 (sol-gel) 製備二氧化矽氣凝膠 (silica aerogel) 之方法，將酵母菌 (yeast) Saccharomyces cerevisiae (S.c) 與葡萄糖澱粉酵素 (Glucoamylase) 分別固定於氣凝膠中。另利用氣凝膠所具備的多孔特性，使包覆於其中的細胞與酵素可和反應物接觸，以HPLC對反應液進行檢測，藉由反應液觀察細胞存活的情況及酵素的催化活性。此外，將包覆S.c之生物氣凝膠回收重覆反應，研究回收之細胞是否仍具有存活能力，且藉由平面培養基質觀察細胞數量的變化。為了比較，本研究也對S.c使用氣凝膠進行物理性吸附法進行固定化，探討物理性吸附的可行性，探討未固定化細胞、包覆式固定化細胞及吸附式固定化細胞之間的差異。結果顯示本研究成功的利用二氧化矽氣凝膠達成S.c的固定化。其中葡萄糖澱粉酵素之生物氣凝膠的部分：透過TGA得知，葡萄糖澱粉酵素亦可包覆於氣凝膠中，但在活性檢測實驗中，固定化過後的酵素活性偏低。吸附S.c之生物氣凝膠的部分：透過TGA及SEM亦可證明S.c確實可吸附於氣凝膠表面，從HPLC檢測出吸附之S.c仍存活，但出芽生殖的情形較旺盛；其缺點為因物理吸附的作用力較弱，導致S.c容易從氣凝膠上脫附至反應液中。包覆S.c之生物氣凝膠的部分：透過TGA及SEM，證明S.c確實包覆於氣凝膠中；從BET得知此生物氣凝膠部分仍具有中孔洞性質；從HPLC及平面培養基質均檢測出包覆之S.c仍存活，並可回收重覆使用。

關鍵字

酵素固定化；酵素；細胞固定化； Saccharomyces cerevisiae ；酵母菌；氣凝膠

並列摘要

Enzyme is reusable but is difficult to recover due to the water-soluble. Now it is focused on the enzyme immobilized technology. Enzyme is expensive and usual to decrease the enzyme activity when the extraction. This study not only immobilizes the enzyme in silica aerogel but also applies in cell immobilized. In this research, silica aerogel was prepared by sol-gel method immobilized yeast (Saccharomyces cerevisiae, S.c) and glucoamylase, respectively. S.c and enzyme encapsulated in silica aerogel contact with reactants due to its porous; the reactive solution is detected by HPLC. In addition, the recycling bioaerogel with S.c is monitored the survive ability for cells by observing the number of cell change via plate agar. Comparison to the bioaerogel with S.c, S.c was also immobilized with silica aerogel by physical adsorption to discuss the difference from free cells, immobilized encapsulated and physical adsorption cells. The results show that silica aerogel encapsulated S.c successfully. In the first part of the bioaerogel with glucoamylase: the TGA data exhibits glucoamylase could be encapsulated in silica aerogel, but the activity decreases. In the second part of the bioaerogel with S.c by physical absorption: the TGA and SEM data shows S.c could be absorbed on the surface of aerogel. The HPLC data shows S.c was still survive. By the way, it is excited in reproduction by budding. The fault is S.c was desorbed from aerogel into the solution easily due to the weak force with physical adsorption. In the final part of the bioaerogel with S.c by encapsulated: the TGA and SEM data exhibit S.c could be encapsulated in silica aerogel, and the N2 adsorption/desorption isotherm shows the bioaerogel posses mesoporous structure. Both the HPLC and plate agar show the S.c encapsulated was alive and reusable.

並列關鍵字

Enzyme ； Saccharomyces cerevisiae ； yeast ； cell immobilization ； aerogel ； enzyme immobilization

參考文獻

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利用二氧化矽氣凝膠固定化酵母菌Saccharomyces cerevisiae

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