Research On The Biotransformation Of Lignin,dyes And Natural Product By Microorganisms

As an important organism in nature,microorganisms play an important role in biotransformation of biomass and natural product.There are many kinds of microorganisms in the soil,which is the most abundant"resource bank"of mankind.The exploration of soil microorganisms has great potential and the relevant research provides the possibility for the sustainable development of the world,the treatment of environmental pollution and the solution of drug resistance.With the development of economy,some agricultural wastes and industrial dye wastewater are discharged into the environment.Lignocellulose waste is a renewable resource with great potential.However,it is difficult to reuse because the cellulose is always wrapped with refractory and rigid lignin.Industrial dyes pollute water resources and environment,while it causes cancer and mutation in mankind.Artemisinin is an efficient drug for curing malaria.However,it has been found that Plasmodium has resistance to artemisinin in recent years,so it is imperative to develop efficient artemisinin derivatives.The biotransformation of lignin,dyes and artemisinin with microorganisms were studied in this work.In this study,the strain FY3 which could degrade lignin effectively was screened in rotten wood and straw piles.According to morphological and molecular identification,it was identified as Penicillium rubens.The enzyme production conditions of the FY3 strain were optimized.The yield of Li P,Mn P and Lac were 2670U/L,1688 U/L and 785 U/L,respectively,under the optimum conditions.P.rubens FY3was used to degrade the lignin of straw by solid-state fermentation(SSF).The lignin of rice straw was degraded from 24.23%to 10.5%in 31 days,and the degradation rate reached 57.06%.The cellulose in delignified straw was hydrolyzed with cellulase for24 hours which released 0.245 mg/m L glucose.Then the CNC were prepared by ultrasonic after enzymatic hydrolysis.The CNC prepared by this method is a uniformly stable fiber with an average particle size of 177.2 nm.The strain FK3-1 with the highest decolorization ability was screened and identified as Fusarium solani.The enzyme in fermentation broth of F.solani FK3-1was purified by ammonium sulfate precipitation,DEAE-Sepharose FF and Sephadex G-75.The purified enzyme molecular weight was about 48 k Da,the specific activity was 31.33 U/mg and the purification multiple was 23.79.The optimum temperature of the laccase was 30?and the optimum p H was 4.Metal ions and chemical agent had an effect on the activity of purified laccase.Cu²⁺with a concentration of less than 10mm can promoted the activity of laccase,while the enzyme was almost inactivated in the presence of Fe²⁺.The decolorization effect of purified laccase on RBBR was further studied.The optimum decolorization temperature was 40?and the optimum substrate concentration was 0.2 mg/m L.Compared with the crude enzyme,the decolorization rate of the purified enzyme was increased by 55%.Artemisinin was biotransformed by Aspergillus Niger CICC 2487,and the product was isolated and purified to obtain a new artemisinin derivative.The new artemisinin derivatives were identified by liquid chromatography-mass spectrometry(LC-HRMS),gas chromatography-mass spectrometry(GC-MS),Fourier transform infrared spectroscopy(FT-IR)and nuclear magnetic resonance(1D and 2D NMR).The structure was 4-methoxy-9,10-dimethyloctahydrofuro-(3,2-i)-isochroman-11(4H)-one(2).Compared with artemisinin,the peroxide bridge in the new derivative molecule was disappeared.The antimalarial activity(IC₅₀)of the new artemisinin derivative was determined by bioluminescence method,and its antimalarial activity almost disappeared.It indicating that the oxygen bridge plays a key role in the antimalarial function of artemisinin.