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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/80329

    Title: 探討溫度暨萃取發酵系統對於Saccharomyces cerevisiae連續生產苯乙醇之影響;Enhanced biotransformation of L-phenylalanine into 2-phenylethanol via cultivation temperature control strategy and extractive fermentation
    Authors: 周筱軒;Siao-Syuan, Jhou
    Contributors: 化學工程與材料工程學系
    Keywords: 酵母菌;苯乙醇;溫度效應;Saccharomyces cerevisiae;2-Phenylethanol;temperature
    Date: 2019-08-08
    Issue Date: 2019-09-03 12:32:30 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 苯乙醇因具有特殊的玫瑰香氣而被大量的應用在香水、化妝品及食品香精中,年產量在全球香料市場中佔有一席之地。利用微生物發酵法,依循Ehrlich pathway的生成途徑,可以透過Saccharomyces cerevisiae將苯丙胺酸轉化成苯乙醇,但在發酵過程中,面臨最大的限制在於產物的抑制效應,會對細胞產生毒性的影響。而且在微生物發酵中,不同培養溫度也會影響微生物的生理狀態和發酵行為,因此本研究主要的目的是在於探討「溫度」環境因子對於S. cerevisiae生產苯乙醇之影響,探討不同培養溫度對於菌體的生長及產物的變化,並結合萃取技術來改善產物抑制的問題。
    研究結果發現在溫度為25℃下最適合S. cerevisiae的生長,但在溫度為35℃下則比較有助於單位菌重轉化成產物的能力,於是設計一種兩階段溫度轉換的策略同時提升菌體及產物的產量,在此操作模式下,苯乙醇的產量可以高達2.53 g/L,與在單一發酵溫度25℃跟35℃時相比下分別提升了15.48 %及22.38 %,最後再結合連續萃取發酵裝置,以Hytrel®作為吸附劑的角色,透過 in situ product removal 技術,減輕產物對於菌體生長的限制,最終苯乙醇的累積濃度可達到4.506 g/L。
    ;2-Phenylethanol (PEA) is one of the important flavor and fragrance compound in the world with a rose-like aroma. In addition, it is widely used in the cosmetics, perfume, and food industries.

    PEA can be produced from L-phenylalanine (L-Phe) through Ehrlich pathway using yeasts. In the fermentation process, the growth of yeast will be limited by product inhibition, cultivation temperature will also has a strong connection with microbial growth and fermentation behavior.

    In this work, we have explored the effects of temperature on bioconversion of L-Phe into PEA using Saccharomyces cerevisiae BCRC21812 as well as develop strategies to enhance PEA production. Experimental results showed that at 25°C, the optimum cells growth was achieved and favored bioconversion yield. But at 35°C was more favorable for product yield based on biomass. Therefore, two-stage batch fermentation by temperature control was conducted. PEA concentration using two-stage fermentation was 2.53 g/L which corresponds to 15.48 % and 22.38 % higher than single-stage fermentation at 25°C and 35°C, respectively.

    To increase the PEA production, the extractive fermentation will be conducted using Hytrel®. In the preliminary test, it showed that Hytrel® can adsorb PEA to reduce the inhibitory effect and non-toxic effect on yeast growth. After the successive extraction and feeding fermentation, the final concentration of PEA was achieved 4.506 g/L.
    Appears in Collections:[化學工程與材料工程研究所] 博碩士論文

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