- 學位論文
γ-胺基丁酸生產菌之篩選及其對豆漿蛋白水解物生轉化γ-胺基丁酸之應用
Screening of γ-aminobutyric acid-producing strain and its application in the bioconversion of γ-aminobutyric acid from soy milk protein hydrolyzate
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摘要
γ-胺基丁酸（GABA）是大腦中神經傳導物質的抑制劑，主要由麩胺酸脫羧酶（GAD）將麩胺酸進行α-脫羧轉化而成，具有抗氧化、抗憂鬱、抗失眠和止痛等作用，富含GABA醱酵食品的研發顯然符合當前高壓文明社會的需求。L-麩胺酸鈉俗稱味精（MSG），可在GABA醱酵反應系統中作GAD生轉化GABA的受質，然而基於健康的考量，消費者會避免選擇添加味精的食品。大豆蛋白富含包括麩胺酸在內的多種胺基酸，取其酵素水解液作為生產GABA的麩胺酸受質替代來源，具有非常高的潛力。本研究使用水解度最高之25% Alcalase與75% Flavourzyme蛋白酶對大豆蛋白進行酵素水解，可有效提高其麩胺酸生成量，並以GABA生產菌株進行醱酵，將其生轉化為GABA。從市場購得的醱酵蔬菜產品中分離出GABA生產菌株，並使用薄層層析（TLC）定量其GABA生產活性的篩選，確認B10菌株為最佳之GABA生產菌株。經以16S rDNA序列比對，得知B10菌株可能屬於Levilactobacillus senmaizukei。根據麩胺酸與GABA之含量分析結果顯示，在前24小時GABA的產量從41 mg/L上升至1777 mg/L，並且在後24小時繼續上升至2078 mg/L，其中，GABA的生產在前24小時幾乎呈現線性增長的趨勢，顯示出其在轉化麩胺酸為GABA方面具有良好的潛力和效率。綜上所述，本實驗證明大豆蛋白酵素水解液可當作GABA醱酵生產的麩胺酸來源，且本實驗所分離篩選菌株B10具有良好的GABA生產能力，可做為生轉化大豆蛋白酵素水解液中麩胺酸為GABA的有效方法。
並列摘要
γ-aminobutyric acid (GABA) is an inhibitor of neurotransmitters in the brain. It is produced primarily through the α-decarboxylation of glutamate, a process catalyzed by the glutamate decarboxylase (GAD), and is known for its antioxidant, antidepressant, anti-insomnia, and pain-relieving effects. The production of fermented foods enriched with GABA is exactly in line with the needs of the current high-pressure civilized society. Sodium form of L-glutamic acid is known as monosodium glutamate (MSG). It can be added as a substrate and converted into GABA through GAD bioconversion. However, due to health concerns, consumers will avoid adding foods with MSG added. Soy protein is rich in various amino acids, including glutamic acid, and has a very high potential as an alternative source of glutamic acid for the production of GABA. In current study, 25% Alcalase and 75% Flavourzyme proteases, which have the highest degree of hydrolysis, were used to enzymatically hydrolyze soy protein and can effectively increase the production of glutamic acid. GABA-producing strains were also used for fermentation to convert it into GABA. GABA-producing strains were isolated from fermented vegetable products purchased on the market, and screened using thin layer chromatography (TLC) to quantify its GABA production activity, andB10 strain was confirmed to be the best GABA-producing strain. After comparing 16S rDNA sequence, it was confirmed that strain B10 may be a member of Levilactobacillus senmaizukei. According to the analysis results of glutamic acid and GABA content, the production of GABA increased from 41 mg/L to 1777 mg/L in the first 24 hours, and continued to increase to 2078 mg/L in the next 24 hours. Among them, the production of GABA showed an almost linear trend increase in the first 24 hours, showing its good potential and efficiency in converting glutamic acid to GABA. In summary, this experiment proved that soybean protein enzyme hydrolyzate can be used as a source of glutamic acid for GABA fermentation production, and the isolated strain B10 has high GABA production potential. It can be used as an effective method to convert glutamic acid in soybean protein enzyme hydrolyzate into GABA.
參考文獻
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