Research On Screening On Highly Effective Bamboo Lignin-degrading Fungus And Extraction Of Raw Bamboo Fiber

At present bamboo fiber is a kind of natural cellulosic fiber and it is a promising fibrous material.Due to bamboo fiber containing hemicellulose or other colloids,we do not use it directly in the textile industry,so the degumming processing of bamboo fiber is necessary.At the moment,chemical degumming is regarded as the most commonly used methods of degumming,but because of the defects,for example,high energy consumption,so more and more researches about the enzyme preparation of bamboo fiber.This dissertation focuses on the research of bamboo lignin degrading strain screening,identification,optimization of fermentation medium,and biological extraction of bamboo fiber,the main results are as follows:(1)Isolation,screening and identification of fungal strains with lignin enzyme activities.Fungal strains with highly lignin-degrading enzymes activity were screened by colorful reactions of guaiacol-PDA plates,aniline blue-plates and determination of enzymes activity.The results indicated that we isolated and purified 34 fungal strains of fungi from 139 decayed bamboo samples.And finally obtained 7 fungal strains with highly enzymes activity from 139 fungal strains by using guaiacol-PDA plates(containing 0.04%guaiacol)and aniline blue-plates.Then the 7 fungal strains were taken into the liquid medium for the determination of enzymes activity.Finally,we got one fungal strain with the highly lignin-degrading enzymes activity which was indentified as Panus lecomtei after the morphological identification and molecular identification.(2)Optimization of liquid medium for Panus lecomtei FG-35.We optimized the liquid medium components to produce the laccase activity of Panus lecomtei FG-35 by using Plackett-Burman design and response surface methodology.The results of single-factor test showed that soluble starch and peptone were the best sources of carbon and nitrogen.Then the Plackett-Burman design was applied to determine the specific medium components affecting laccase activity and found that soluble starch,Ca2+ and Tween-40 were the key factors.Based on these results,steepest ascent experiments were applied to find central points of laccase activity.These significant parameters were further optimized using Box-Behnken design,response surface methodology and regression analysis.Finally,the optimal medium was:soluble starch 10.04g/L,peptone 0.2g/L,K2HPO4 1.00g/L,ZnSO4·7H2O 0.008g/L,MgSO4·7H2O 0.5g/L,CuSO4·7H20 0.007g/L,FeSO4·7H2O 0.005g,MnSO4 0.035g/L,CaCl2 0.0816g/L,VB1 O.lg/L,Tween-40 0.4%and 3,4-dimethoxy-Benzenemethanol 0.05g/L.Under these optimal conditions,the activity of laccase increased from 263.31U/mL to 127.194U/mL(1.07-fold increase in total yield),similar to the predictions.(3)Study on bamboo fiber bio-extraction process.Using single factor,Box-Behnken experimental design and response surface analysis to determine the biological extraction of bamboo fiber degumming process conditions.And the conditions was:initial pH 6.60,degumming temperature 38?,degumming time 54h,the initial amount of fungi 20mL,bath ratio 1:25;obtain conditions through single factor and orthogonal experiment bleached bamboo fiber was:hydrogen peroxide concentration of 10g/L,bleaching temperature is 60? and bleaching time was 80 min.The best process of bamboo fiber bio-extraction:sample preparation-pretreatment-biologydeguml-autoclave-washing-rolling in silk-biology degum2(Repeat degumming-Autoclave-washing-rolling in silk)-H2O2 bleaching-washing-drying-Bamboo fiber.