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|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|
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。
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.
|Appears in Collections:||食品暨應用生物科技學系|
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