| The RAF106 strain was isolated from Pu er tea in the early stage of this research group, and was identified as Aspergillus niger. The strain can be converted into non ester type tea polyphenols in tea polyphenols. In this study, RAF106 was cultured by Aspergillus niger, and the mycelium could be transformed into tea polyphenols by whole cell biology, which could improve the conversion efficiency, reduce the cost of conversion, and the protection of non ester type. The main results are as follows:(1) Effects of glucose on the transformation process of tea polyphenols from RAF106 spores.Fermentation process: sugar fermentation broth p H was significantly lower than that of non sugar fermentation liquid; and biomass growth rate was significantly higher than that of sugar free broth, add sugar group mycelium crude enzyme liquid test to tannase activity, the hyphae can be measured to tannase activity; The reducing sugar in the sugar group was reduced from 42.82mg/m L to 22.02±0.10mg/m L, and the latter reducing sugar was maintained at a lower concentration, which was 4.33±0.33mg/m L. Two groups of fermentation liquid of tea polyphenols in 0h~60h were significantly reduced, 60 h after no sugar group tea polyphenol does not change significantly, sweetened tea polyphenol increases slightly. 0h~24h: EGCG decreased significantly in two groups of fermentation liquid; GA and EGC were significantly increased; sugar in GA group increased to 4.3789±0.3616mg/m L; EGC increased to 5.8204±0.6051mg/m L; sugar free GA group increased to 4.0542±0.0444mg/m L, EGC IV increased to 7.1005±0.6583mg/m L. 24 h after change of catechins in sugar group was not significant, sugar-free group no significant change in EGCG, EGC and GA are significantly reduced.(2) Effects of different conditions on the growth of RAF106.The colony growth rate of RAF106 at 28? was significantly better than that at 37? and no growth at 48?. The higher the concentration of tea polyphenols on RAF106 colony growth inhibitory effect becomes more obvious.Tea polyphenols concentration is low, the hypha growth positively related to the tea polyphenol content;When the concentration of tea polyphenols 4% or higher, tea polyphenol content had no significant effect on mycelial growth.When yeast powder concentration 0.05% ~ 1.00%, and RAF106 hyphae growth are related.(3) Optimization of mycelium inducing conditions of RAF106.For conversion of catechin ability strongest hyphae, best induced condition is: tea polyphenols 1%, yeast powder adding quantity 0.1%, 36 h of incubation time.Fungus powder inoculation to the tea polyphenols liquid medium, fermentation with uncooked 12 h, ester type catechins were significantly decreased, the ester type catechins were significantly increased: EGCG decreased by 36.45%;EGC increased by 254.07%; GA has increased 217.12%.(4) Optimization of the conditions of RAF106 mycelium transformation of tea polyphenols.Hyphae RAF106 transformed ester type catechins for non ester catechin is the optimum temperature for 48?, fermentation 12h:EGCG by 5.8164±0.4358mg/m L fell to 3.9136±0.4578mg/m L, decreased 32.71%; EGC by 2.1059±0.1015mg/m L increased to 5.5014±0.6336mg/m L, increased 161.24%; GA consists of 0.0945±0.0118mg/ml increased to 2.7519±0.3032mg/m L, increased 2812.23%.Tea polyphenol content is 5%, the mycelium of RAF106 transformed ester type catechin is the efficiency of non ester catechin highest; tea polyphenol content is more than or equal to 15%, the ester type catechins and non ester catechin decreased significantly in the fermentation process, GA without significant changes. When the tea polyphenol concentration is high, the addition of carbon and nitrogen source can protect the ester type and the non ester type of the tea polyphenol is not consumed, but no help to the generation of non ester type of tea.At the early stage of the fermentation mycelia addition amount is higher, the faster rate of ester type catechin transformation of RAF106 element produces non ester type catechins, but excessive amounts of bacteria powder is not conducive to catechin eventually maximum conversion. Bacteria powder adding amount was 0.2%, fermentation 12h:ECG and GCG total conversion; EGCG by 19.1946±0.7781mg/m L fell to 5.7803±0.1416mg/m L, reduce the 69.89%, EGC by 5.0053±0.1804mg/m L increased to 11.1899±0.7521mg/m L, increased 123.56%, EC by 2.5149±0.0890mg/m L increased to 3.8335±0.3152mg/ml of increase 52.43% and 12 h after three no significant change. GC in the fermentation process is maintained at a low concentration; GA by 0.2062±0.0059mg/m L fermentation 36 h reached the highest concentration of 7.3903±0.2367mg/m L, an increase of 3484.53%, after a slight decrease.By orthogonal test, the optimum conditions for the transformation of RAF106 mycelium into tea polyphenols were as follows: the amount of yeast powder was 0.2%, the adding amount of bacterial powder was 0.2%, and the fermentation time was 24h. |
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