臺灣博碩士論文加值系統

苯乙醇具有玫瑰香氣而廣泛用於各種食用香精和化妝品中，全球每年大約生產約10000噸的苯乙醇，其中大部分的苯乙醇都是利用化學方式所合成，但化學法對於環境和健康有很大的危害，因此美國和歐盟對於化學合成的苯乙醇應用在化妝品和食品添加上有嚴格的使用限制，因此如何透過較低的成本和對保護環境的原則下去取代以往化學法所合成的苯乙醇成為了工業發展的趨勢，像是利用微生物發酵的生成則成為一個替代性的平台。
一些研究指出，酵母菌在發酵過程中，可以透過苯丙胺酸生物轉化生成苯乙醇，然而發酵過程中，面臨最大的挑戰為產物的抑制效應，隨著產物苯乙醇和副產物乙醇在發酵過程中累積濃度的增加，會降低生物轉化率導致產物苯乙醇產率的減少和對細胞造成毒性的影響。
本研究設計一個生物反應器－Polydimethylsiloxane (PDMS)海綿連續式萃取發酵系統，PDMS海綿在此處為萃取劑的角色，利用擠壓海綿進行吸附脫附的過程，透過 in situ product removal技術，可以減輕副產物乙醇和產物苯乙醇對菌體之毒性，從而提高主要產物苯乙醇濃度，產量及生產率。
 

2-phenylethanol is widely used in the cosmetics and perfumery for fragrance modification with rose-like fragrance. Every year about 10000 tons of 2-phenylethanol are produced worldwide, the most of which through chemical synthesis. The chemical synthesis of 2-phenylethanol can be done by Friedel-Craft reaction. Though inexpensive, these processes are disadvantaged by low selectivity for the desired product and accompanied by the formation of toxic by-products. This makes the chemical production of 2-phenylethanol detrimental to the environment and health. Therefore, legislations of the US and EU have restricted the use of chemical 2-phenylethanol in cosmetics and food products. Therefore, how to replace the 2-phenylethanol by the chemical synthesized has become the trend of industrial development through the lower cost and the principle of protecting the environment, such as the use of microbial fermentation is becoming an alternative platform.
Yeast fermentation has become the focal point of research effort utilizing the Ehrlich pathway wherein the L-phenylalanine is converted to 2-phenylethanol. However, 2-phenylethanol and ethanol have common inhibitory effect for yeast fermentation. Many studies had proved that product can be removed through in situ product removal techniques and the yield of product will increase.
In this study, owing to the sponges have the hydrophobic property, it can adsorb 2-phenylethanol. So, we use the PDMS sponges to remove 2-phenylethanol, in order to reduce the inhibitory effect. By using the PDMS sponges, the yield of product can be increased and the extracted energy cost can be reduced.

目錄
摘要 i
Abstract ii
目錄 ii
表目錄 vii
圖目錄 viii
第一章 緒論 1
1.1 研究背景 1
1.2 研究目的 2
第二章 文獻回顧 4
2.1 香精香料發展趨勢與市場介紹 4
2.2 芳香化合物2-苯乙醇 5
2.2.1 2-苯乙醇用途介紹 5
2.2.2 2-苯乙醇的生理學作用 6
2.2.3 2-苯乙醇的生產方式 6
2.3 酵母菌（Saccharomyces cerevisiae） 10
2.3.1 酵母菌之基本介紹 10
2.3.2 酵母菌之生殖方式 13
2.3.3 酵母菌之生長條件 14
2.3.4 酵母菌的抑制效應 15
2.4 影響發酵的物理化學因子 16
2.4.1 溫度 16
2.4.2 通氣量 16
2.4.3 pH 16
2.4.4 發酵方式 17
2.5萃取方法之介紹及發展 17
2.6 聚二甲基矽氧烷海綿 20
2.6.1 聚二甲基矽氧烷基本性質 20
2.6.2 PDMS海綿之介紹及應用 22
第三章 實驗規劃、材料與方法 24
3.1 實驗規劃 24
3.2 實驗材料、設備與裝置 25
3.2.1 實驗菌株 25
3.2.2 實驗藥品 25
3.2.3 實驗儀器與設備 27
3.3 實驗方法 29
3.3.1 菌種保存 29
3.3.2 培養基組成 29
3.3.3 PDMS海綿製備 32
3.3.4 實驗裝置 33
3.4 分析方法 35
3.4.1 菌重濃度測定 35
3.4.2 葡萄糖殘量測定 36
3.4.3 乙醇濃度分析 38
3.4.4 苯乙醇和苯丙胺酸濃度分析 40
第四章 實驗結果與討論 43
4.1 不同發酵方式對於Saccharomyces cerevisiae生產苯乙醇之影響 43
4.2 好氧發酵－PHE濃度對Saccharomyces cerevisiae發酵之影響 45
4.3 好氧發酵－通氧量對Saccharomyces cerevisiae發酵之影響 50
4.4 兩階段式通氣發酵對Saccharomyces cerevisiae之影響 53
4.5 抑制效應對Saccharomyces cerevisiae發酵之影響 55
4.5.1乙醇濃度對於Saccharomyces cerevisiae 發酵之影響 55
4.5.2 苯乙醇濃度對於Saccharomyces cerevisiae 發酵之影響 58
4.6 PDMS海綿萃取發酵系統 61
4.6.1 抑制萃取時機選擇 61
4.6.2 兩階段式通氣連續萃取發酵並添加饋料測試 62
4.6.3 三階段式通氣連續萃取發酵並添加饋料測試 64
第五章 結論 66
第六章 參考文獻 68

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