用半乳寡糖酶催化和酵母菌醱酵生產高純度半乳寡糖

Production of High-Content Galactooligosaccharides by β-Galactosidase Catalysis and Yeast Fermentation

戴偉倫(Wei-Lun Tai)

指導教授 ： 許垤棊

大同大學/工程學院/生物工程學系所/碩士(2005年)

摘要

半乳寡糖能促進腸道中比菲德氏菌和乳酸菌等益菌的增殖，增進人體健康，而受到重視。半乳寡糖是由2至5個單糖所構成的寡糖，其單糖分子主要以半乳糖為主。市售的半乳寡糖主要是利用半乳糖苷酶的半乳糖基轉移活性，將乳糖轉變成半乳寡糖。由於酵素的性質，市售半乳寡糖含有大量的葡萄糖和乳糖，不但半乳寡糖的含量低，而且不利於乳糖不耐症的消費者。本研究主要是用混合酵素系統，亦即半乳糖苷酶和葡萄糖氧化酶，以提高半乳寡糖的產率。其中葡萄糖氧化酶在反應過程中，可將副產物葡萄糖氧化成葡萄糖酸，和碳酸鈣形成鈣鹽沉澱。另外利用酵母菌Kluyveromyces marxianus的醱酵，可將半乳寡糖中的葡萄糖和乳糖等不純物移除，形成接近純度95% 以上的半乳寡糖商品。研究過程中，比較來自Kluyveromyces lactics、Aspergillus oryzae以及環泰公司的半乳糖苷酶，其中以環泰公司的酵素能夠產生較多的半乳寡糖。而混合酵素系統將半乳寡糖的產率由25% 提高至28 %。而經由酵母菌Kluyveromyces marxianus的醱酵，則可將半乳寡糖的乾重純度由25 % 提高至96 %。

關鍵字

半乳寡糖、混合酵素系統、醱酵、Kluyveromyces marxianus

並列摘要

Galactooligosaccharides (GOS) have been received increasing interest, because they can promote the proliferation of bifidobacteria and lactic acid bacteria in the human intestine and thus enhance the human health. GOS is the collective name of oligosaccharides constructed by 2-5 glycosyl moieties, mainly galactoside. Commercial GOS are produced from lactose by the transgalactosyl catalytic activity of β-galactosidase. Because of the enzymatic behavior, commercial GOS consisted of large amount of glucose and lactose. Such product not only was a low-content GOS, but also was not available for the lactose-intolerant people. The present study engaged in the enhancement in GOS yield by a mixed-enzyme system and the increase in GOS content by the yeast fermentation. Among the β-galactosidases from Kluyveromyces lactics, Aspergillus oryzae and Huang-Tai Company, the enzyme from Huang-Tai Company resulted in the highest concentration and yield of GOS. In the mixed-enzyme system, in which β-galactosidase and glucose oxidase were used, the glucose byproduct was converted into calcium gluconate precipitate and the GOS yield was increased from 25% to 28%. During the fermentation of low-content GOS by Kluyveromyces marxianus, the digestible sugars including glucose and lactose were depleted and the GOS content was increased from 25% to 96%, on a dry weight basis.

並列關鍵字

fermentation ； Galactooligosaccharides ； Kluyveromyces marxianus ； mixed-enzyme system

參考文獻

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