Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/50769
標題: Effects of environmental factors on the biosynthesis of some key enzymes and metabolites by tea fungus prepared by pure culture and traditional cultivation methods
環境因子對以傳統移殖及純菌培養法製備紅茶菇時關鍵酵素暨產物生合成之影響
作者: Li-An, Lai
賴麗安
關鍵字: 紅茶菇
Tea fungus
醋酸
葡萄糖酸
細菌性纖維素
acetic acid
gluconic acid
bacterial cellulose
出版社: 食品科學系
摘要: 摘要 紅茶菇為一種以醋酸菌及酵母菌為主所形成的共生體系,其乃由上層之纖維質薄膜及下層培養液所組成,後者之成分以醋酸、酒精及葡萄糖酸為主。傳統之製備方法係將上層之纖維質薄膜及少量培養液為種母移至一新配含有蔗糖之紅茶湯液中,於開放條件下培養五至七天即得。本研究分別以傳統移植法保存之紅茶菇及以由紅茶菇分離之醋酸菌(Acetobacter xylinum, Acetobacter aceti)酵母菌(Schizosaccharomyces pombe)等來製備紅茶菇,以探討環境因子,如碳、氮源成分暨靜置、震盪與添加物等,對紅茶菇重要酵素之調節作用以及產物生合成之影響。 在碳源種類及濃度對紅茶菇發酵產物之影響方面,以蔗糖濃度為15%時之酒精、醋酸及葡萄糖酸濃度均為最高,分別為4.3%,6.1%及1.6。醋酸除來自酒精之氧化外,亦可透過NADP-G6PD酵素途徑而產生。至於纖維素產量,以碳源為15%葡萄糖時產量最高,其生產變化量與NAD-G6PD及UDPG-pyrophosphorylase之酵素等相對活性呈正相關。玉米浸漬液為紅茶菇發酵之良好氮源,當濃度高時(1%),除可刺激酵母菌invertase之活性進而促進蔗糖之消耗並生成高量酒精外,亦有提昇葡萄糖酸產量之效果。此外,隨玉米浸漬液濃度之增加因其內所含乳酸可供生產ATP能量,致使NAD-G6PD酵素活性下降,而 UDPG-pyrophosphorylase酵素之活性則相對提高,因而增加纖維素產量。酒精、乳酸及甘油等添加物濃度對於酵母菌之酵素invertase的影響並不顯著,而對傳統和純菌培養間之影響效果亦甚微。酒精及乳酸因能直接被代謝並產生能量,為醋酸菌之良好之能量來源,由於NAD-G6PD酵素活性被抑制,推測此時之有機酸多由與細胞生合成相關之NADP-G6PD而來。此外,此等添加物可促進纖維素合成,惟甘油與乳酸之效果推測與葡萄糖六磷酸量之增加有關;而酒精的則與UDPG-pyrophosphorylase酵素之活性變化相關。震盪培養可提昇invertase之活性,亦可增加溶氧量,提高酒精之氧化速率進而增加醋酸產量。另外,亦可有效促進纖維素之產生。同時發現葡萄糖酸量與UDP-G6PD酵素活性呈負相關,此表示纖維素合成之活性隨葡萄糖酸之產生而下降。
Abstract The tea fungus (commonly named as “kombucha”) is a symbiotic culture of having acetic acid bacteria and yeasts as two major microorganisms. The tea fungus is composed of two portions, a floating cellulose pellicle layer and the sour liquid broth. Acetic acid, ethanol, and gluconic acid, are the major components found in the liquid broth. The fermentation is traditionally carried out by transplanting a symbiotic culture, accompanied with the product cellulose, into a freshly prepared, sucrose-containing black tea under aerobic conditions for 5-7days. In this study, using the tea fungus by traditional culture and pure culture method of using acetic acid bacteria (Acetobacter xylinum, Acetobacter aceti) and yeast (Schizosaccharomyces pombe) isolates as starter, the effects of environmental factors such as carbon sources, nitrogen sources, supplements and agitated culture on the regulation of some key intracellular enzymes and biosynthesis of metabolites in the tea fungus will be investigated. The effects of fermentation products in the tea fungus supplied with varies carbon sources and concentrations was could reach the highest concentration of ethanol, acetic acid, and gluconic acid that under 15% sucrose, they are 4.3%, 6.1%, and 1.6%. Besides oxidation ethanol, acetic acid can produce from NADP-G6PD pathway. When the carbon source supplied with 25% glucose, we could see the highest cellulose production, and cellulose production was depended on the activity of NAD-G6PD and UDPG-pyrophosphorylase. Corn steep liquor is a good nitrogen source during the fermentation of tea fungus, under 1% corn steep liquor could stimulate invertase activity of yeast, produce high level ethanol from oxidation sucrose. At this concentration could also increase the gluconic acid production. Otherwise, the increase of lactic acid with the corn steep concentration increase, and ATP could produce from lactic, the enzyme activity of NAD-G6PD was decrease, and the activity of UDPG-pyrophospholyase was increase. With the enzyme activity increasing of UDPG-pyrophospholyase, the cellulose production was increased at the same time. There is no significant effect of yeast invertase on the concentration of adding ethanol, lactic acid, and glycerol. And there is no observed effect between traditional and pure culture. Acetic acid bacteria can metabolite ethanol and lactic acid directly become energy, and the enzyme activity of NAD-G6PD was inhibited, the organic acid was came from cell biosynthesis enzyme NADP-G6PD. Ethanol, lactic acid, and glycerol can promote cellulose biosynthesis. The effect of glycerol and lactic acid maybe is related to the amount glucose-6-phosphate, and the effect of ethanol is related to the activity change of UDPG-pyrophosphrylase. Agitated culture could promote the enzyme activity of invertase and increase the dissolved of oxygen to speed up the oxidation of ethanol and acetic acid production. In the same way, the cellulose production was inhibited. And we found the amount of gluconic acid is negative related to the enzyme activity of UDPG-pyrophosphrylase, it also means that the activity of cellulose production decrease with the gluconic acid production.
URI: http://hdl.handle.net/11455/50769
Appears in Collections:食品暨應用生物科技學系

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