| Eurotium cristatum is the dominant strain in the fermention process of Fuzhuan brick-tea.Beta vulgaris L.and Steviol glycoside are the most important sugar-bearing crops and commodity crops.This study was mainly on lovastatin fermentated by Eurotium cristatum which growing on beet powder and Steviol glycoside biotransformed by Eurotium cristatum.Meanwhile,the safety of Eurotium cristatum fermention products was detected by Caenorhabditis elegance.The results were as follows.(1)In this work,beet powder was discovered as the best natural medium,it was better than sugar beet pulp and wheat bran.When in the beet powder medium,the strain grew more vigorous and the fermention products were rich in lovastatin(a hypolipidemic drug).For further study,Eurotium cristatum which cultivated by beet powder had the highest lovastatin level(95 mg/kg),while in sugar beet pulp medium the lovastatin is 39 mg/kg and in wheet bran medium the lovastatin is 15 mg/kg.So beet powder medium was chosen in further study.(2)Study the factors which influence Eurotium cristatum producing lovastatin,the results showed that in all precursors,Vitamin B2(with a addition of 0.15%)could make the production of lovastatin significantly raise 41%(134 mg/kg)compared with no precursors.Choose 4 factors to conduct Orthogonal test,the results showed the influence order of all factors are:precursors concentration(A)>inoculum concentration(D)>fermentation time(C)>fermentation temperature(B)(The optimum extraction technology is A2B3C1D2).That means when Vitamin B2 was with a addition of 0.15%,the inoculum concentration was 16%,the fermentation temperature was 32→30℃(the first three days 32℃ and then transferred to 30℃)and the fermentation time was 5 days,the production of lovastatin could reach 146.4 mg/kg.(3)Study the process of Steviol glycoside biotransformed by Eurotium cristatum.The results presented that Eurotium cristatum can transform Stv specifically and had no function to RA.The new product was identified as RS by HPLC and LC-MS/MS.Choose the transformation characteristics for further study,the results showed that Lactose Monohydrate had the maximum conversion,but in consideration of cost,glucose was chosen as the optimum carbon source,when its addition was 0.9%,the biotransformation rate was 90.8%after 36 h;the optimum nitrogen source was soybean meal,when it was added as the nitrogen source the biotransformation rate could reach 93.5%.(4)Study the safety of Eurotium cristatum fermention products using Caenorhabditis elegance.The survival rate indicator showed that the survival rate in Eurotium cristatum fermention broth was higher than control,while in Fusarium sp.fermention broth was much lower than control,it presented that there was some beneficial substance for Caenorhabditis elegance in Eurotium cristatum fermention broth while there was some harmful substance in sp.fermention broth;The head oscillation frequency and body bending frequency indicators showed that the head oscillation frequency of experimental group(95/min)was 2.32 times than control(41/min)and body bending frequency of experimental group(31/min)was 2.21 times than control(14/min),it presented that there was some substance which could enhance Caenorhabditis elegance’s motor function in Eurotium cristatum fermention broth;the number of offspring indicator showed that experimental group had no significant difference with control,it presented that Eurotium cristatum fermention broth had no damage effect on Caenorhabditis elegance.In all,Eurotium cristatum fermention broth had a high safety on Caenorhabditis elegance,thus it could provide a favorable living environment to Caenorhabditis elegance. |
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