Degradation Of The JUNCAO By White-rot Fungus And Its Characteristics Of Lignocellulose-degrading Enzyme System From White-rot Fungi

Lignocellulose is composed of cellulose,hemicellulose and lignin,and is the most abundant and renewable bio-resource in nature,respectively.However,it can't be fully utilized at present because of the difficulty in degradating and transforming lignin.White-rot fungi are a kind of the effective microbes that have strong potential to degradate.Phanerochaete chrysosporium,a model microorganism in studying lignin bio-degradation,has been extensively studied.However,it produces low ligninolytic enzymes and little laccase,which is the important member of ligninolytic enzyme system.Therefore,the screening of strains with high yield of ligninolytic enzymes,the mechanism of lignin biodegradatiom,purification of lignin peroxidases are important to be further investigated in the lignin biodegradatiom.In this dissertation,for the general purpose of investigating the effective biodegradatiom,eight strains were able to produce positive reaction,through detecting 14 strains' growth status and eznyme activity on the medium containing three different substrates i.e.guaiacol,aniline and tannic acid substrates;The ratio of weight loss lignin and cellulose(SF index)was uesed as indicators,these strains were determined.The SF index of P.Ostreatus 10969 and Pleurotus WP1 were 2.31 and 1.86,respectively.Comparing to P.chrysosporium RP78 and P.chrysosporium BKM-F-1767,strain Pleurotus ostreatus(Jacq.:Fr.)Kummer,Po10969)and Ganoderma applanatum WP1 were selected from the 14 strains,because they had the highest speed in growth and the best ability to secrete eznymes.They had not only growth superiority but also strong ability in laccase secreting and lignocellulose degradation.During solid fermentation cultivated with P.ostreatus 10969 cultivation process, only laccase was detected,of which the activity was 1807 U/mL and the activity decreased gradually with the continue cultivation,but LiP and MnP were not detected. Matrix surface groups of JUNCAO were also performed by Fourier transform infrared spectrometry(FTIR).Purification factor of fermentation broth was 3.67 after ammonium sulfate fractionation,gel filtration chromatography.The molecular weight of purified protein was about 40 kDa.The characteristics of the purified were performed.Meanwhile,the cellulase(egl2)and the semi-cellulose(xyn2)gene were cloned, expression of both genes and activity of eznymes were performed.Reducing sugar content of different fiber materials,which were soaking with the crude enzymes solution,were determined.As result,the reducing sugar content was:JunCao P. sinese Roxb treated with NaClO₂＞JunCao P.sinese Roxb treated with Po 10969＞Cao P.sinese Roxb without being treated.In this paper,screening white-rot fungi degradation of lignin of JunCao,isolation and purification of laccase,cellulose fiber material soaking with the crude enzymes were performed.With white-rot fungus,we can make full makes full use of grass resources,to decrease pollution and produce fuel ethanol,which have an important significance of the application.