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Microbial fermentation is a kind of enzymatic catalytic reaction essentially, which using various kinds of enzymes secreted by the microorganism during t he growth of strain. It has advantages for mild reaction conditions, simply oper ating, low cost producing, less hazardous, complex chemical synthesis, natural product transformation. Buckwheat is a kind of important food crops in mounta in area of Sichuan, Yunnan, Guizhou and Shanxi provinces. In the organs of st alks, leaves, seeds and brans of Buckwheat, which containing rutin in high lev el, are usually abandoned as waste of production, its economic value not be fu lly utilized yet.In this experiment, a strain, which has the activity of hydrolyzing rutin to quercetin, has been use into fermentation to preparation quercetin from Buckwh eat. By this study, I’m trying to build up a process as a theoretical guidance f or industrial production of quercetin from Buckwheat.We investigate the impact of the strains growth curve, medium the sucrose, the content of rutin, temperature and cultivation ratio to strain growth. By ort hogonal experiment of optimization culture conditions, the results shows that op timal conditions for strain cultivation is sucrose 25g/L, culture temperature 3 2℃, rutin 2g/L, training time 64 hours.By study the impact of the ethanol concentration, extraction time, solid-liq uid ratio on the recovery ratio of products, the results shows that optimum con dition of extraction is ethanol5%, solid liquid ratio 8:1, heating extracting 2 ho urs.We investigate the impact of seed age, inoculation quantity, medium pH, i norganic salt, nitrogen source, carbon source to fermentation. By orthogonal ex periment of optimization the fermentation conditions of preparation quercetin fr om Buckwheat, the results show that the best condition is inorganic salt (0.0 1%, zinc sulfate), solid liquid ratio 2.5(v/w), the incubation temperature 32℃, extra carbon sources (sucrose) 20g/L.Choosing the organs of stalks, leaves, seeds and brans of Buckwheat for f ermenation substrate, detecting the quercetin yielding ratio, achieved 89.1% 94. 3% 91.2% and 87.3% respectively, and the purity of products>73%.For the study of the mechanism of fermentation, we extract P-O-glycosidas e from the strain, and purification by gel column chromatography (Sephadex G-75) and anion exchange column chromatography (DEAE cellulose-32), and det ermination the molecular weight ofβ-O-glycosidase by SDS-PAGE. The specifi c activity of enzyme increased from 56.3U/mg to 362.27U/mg, purification fold s reached 6.43 folds, recovery of 3.5%. Molecular weight is approximately 68 kDa. By investigating the impact of pH and temperature to the enzyme activity, the results show that the optimum pH is 6.0, the optimum temperature is 4 0℃.
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