Study On The Production Of Ganoderma Lingzhi Polysaccharides And Triterpenes By Gradient Degradation Of Poplar

China has abundant resources of agricultural and forestry residues.How to develop and utilize the agricultural and forestry surplus resources scientifically and efficiently is of great significance for building a resource-saving and environment-friendly society.Lignocellulosic biomass has become a potential green resource due to its abundant resources,environmental friendliness and sustainability.Ganoderma lingzhi is a kind of white rot fungi with high degradation ability of lignocellulose.It could produce metabolites of polysaccharides and triterpenoids,which showed great edible and medicinal value.Therefore,how to use lignocellulose residues as raw materials to produce polysaccharides and triterpenoids by G.lingzhi fermentation is one of the key problems to realize the industrial production of high-value secondary metabolites of G.lingzhi,which has important research value.In this study,poplar sawdust powder was used as raw material,which was degraded by microorganism.Then G.lingzhi was used to produce polysaccharides and triterpenoids by gradient degradation and fermentation.The main results were showed as follows:1.Screening of poplar degrading fungiIn this part,the comparison of degradation abilities of poplar by three lignocellulolytic fungi strains including Trametes hirsuta X-13,Trametes versicolor Z-1 and Peniophora incarnata T-7 was carried out.The results showed that the activities of total cellulase(FPA),exoglucanase(CBHA),endoglucanase(EGA),laccase(Lac)and manganese peroxidase(MnP)of T.hirsuta X-13 were the highest among these strains,with the values of 19.29 U/mg,23.28 U/mg,41.59 U/mg,2×105 U/mg and 8×103 U/mg,respectively.While the highest activity of β-glucosidase(BGA)was obtained from P.incarnata T-7,with the value of 38.75 U/mg.Fourier transform infrared spectroscopy(FT-IR)combined with scanning electron microscopy(SEM)analysis showed that the lignocellulose structure of poplar was deconstructed in varying extents after pretreated by T.hirsuta X-13,T.versicolor Z-1 and P.incarnata T-7 fermentation.The main component of poplar analysis showed that the highest degradation rates of lignin and polysaccharides(hemicellulose and cellulose)were obtained by T.hirsuta X-13 and P.incarnata T-7 respectively,with the values of 11.56%,9.05%and 13.59%respectively.Poplar powder pretreated by T.hirsuta X-13,T.versicolor Z-1 and P.incarnata T-7 were used as substrates respectively.After seven days of degradation and fermentation of G.lingzhi,the results showed that the poplar substrate pretreated by T.hirsuta X-13 was the most suitable for G.lingzhi subsequent fermentation and production of active products.The cell biomass of G.lingzhi,the concentrations of polysaccharides and triterpenes were the highest in the poplar substrate pretreated by T.hirsuta X-13,which were 12.57 g/L,673.61 mg/L and 67.31 mg/L,respectively.2.Study on poplar predegradation and G.lingzhi subsequent degradation fermentation modeThe degradation of G.lingzhi and the utilization of different treated poplar powder by simultaneous fermentation were studied.The results showed that the concentrations of polysaccharides and triterpenes produced by G.lingzhi from T.hirsuta X-13 pretreated poplar were higher than those of alkaline pretreatment.Meanwhile,compared with the control group which only added soluble starch as carbon source,the higher activities of Lac and MnP was detected in media contains both soluble starch and T.hirsuta X-13 pretreated poplar substrates,with the values of 127.75U/mg and 189.58U/mg,respectively,albeit the cellulase activity was lowe.Furthermore,the optimization of poplar concentration added in G.lingzhi fermentation was conducted.The results showed that the maximum of G.lingzhi growth biomass,polysaccharides and triterpenes concentrations were obtained under the supplementary concentration of 25g/L poplar,with the values of 15.6 g/L,730.21 mg/L and 77.38 mg/L,respectively.These suggested that the production of polysaccharides and triterpenoids by G.lingzhi from poplar substrate could be effectively enhanced by T.hirsuta X-13 pretreatment on poplar prior to G.lingzhi fermentation.3.Optimization of fermentation medium for polysaccharide and triterpenoid production from poplar degradation products transformed by G.lingzhi.The optimization of supplementary components of medium containing T.hirsuta X-13 pretreated poplar for production of polysaccharides and triterpenes by G.lingzhi fermentation was performed.The results showed that on the basis of 25g/L of poplar wood degradation,the optimization of supplementary components of medium contained 15g/L soluble starch,2.5g/L peptone and 2.5g/L yeast powder.Furthermore,Box-Behnken design was used to get the the optimal culture conditions of polysaccharides were poplar degradable substance 25g/L,soluble starch 17.01g/L,yeast powder 2.58g/L,peptone 2.58g/L,and the yield of polysaccharides was 1021.46mg/L.The optimal culture conditions for triterpenoids in G.lingzhi were poplar degradable substance 25g/L,soluble starch 17.57g/L,yeast powder 2.54g/L and peptone 2.41g/L,and the yield of triterpenoids was 120.73mg/L.4.Optimization of fermentation conditions for polysaccharide production and triterpene production from poplar degraded products transformed from G.lingzhi.The single factor experiment was conducted to optimize the fermentation conditions of polysaccharides and.triterpenes production by G.lingzhi from T.hirsuta X-13 pretreated poplar.The results showed that the optimization of fermentation conditions of G.lingzhi were obtained incubation 7d,culture temperature 28℃,shaking speed 160r/min,initial pH 6.5,liquid volume 100mL/250 mL and inoculation volume 10%(v/v).Furthermore,Box-Behnken design was used to get the the optimal culture conditions of polysaccharides were inoculation volume 8.33%,shaking speed 150.36r/min,culture temperature 27.64℃,and the yield of polysaccharides was 1357.96mg/L.The optimal culture conditions of triterpenoids were inoculation volume 8.77%,shaking speed 162.64r/min,culture temperature 27.67℃,and the yield of triterpenoids was 144.56mg/L.In this work,we obtained the optimization conditions for the efficient production of polysaccharides and triterpenes production by G.lingzhi through screening of fungi used for poplar pretreatment,and optimization of medium components and fermentation conditions for polysaccharides and triterpenes production by G.lingzhi from pretreatment poplar wood.These results laid a theoretical foundation for promoting of industrial production of polysaccharides and triterpenes by G.lingzhi from lignocellulosic biomass substrate.