Studies On Degradation Difference Of Three Kinds Of Lignocellulose With White Rot Fungi

White rot fungi have been extensively used in biological treatment of lignocelluloses. It is important to study the degradation difference of lignocelluloses with white rot fungi for further understanding the mechanism of the biodegradation. This work evaluated the degradation difference of three kinds of lignocelluloses, from Weeping willow (Salix babylonica), China fir (Cunninghamia lanceolata) and Moso bamboo (Phyllostachys pubescence) respectively, and investigated the effect of enzyme production and lignocellulose reactivity to cellulase on the degradation difference during the biodegradation with white rot fungi.Firstly, degradation patterns of 49 isolates of white rot fungi were evaluated on the Moso bamboo lignocellulose and it was found that Echinodontium taxodii 2538 and Hygrophorus sp. 254 have the potential for the biotreatment of Moso bamboo. Degradation patterns of 10 fungi which were selected according to the first evaluation were evaluated after 4-weeks degradation by Principal Component Analysis (PCA). Degradation difference of Trametes vesicolor G20 and Echinodontium taxodii 2538 were further studied during the lignocellulose biodegradation. The result indicated that Differences in the increases of the cellulose-degrading rate resulted in the degradation difference during the biodegradation with white rot fungi.Secondly, enzyme production during the biodegradation of the three lignocellulose with Trametes vesicolor G20 and Echinodontium taxodii 2538 was measured. There was no significant relationship between the degradation difference and cellulase activity during the biodegradation of the different lignocellulose. The levels of cellulase activity were lower at advanced decay stages than at early decay stages. There were no significant difference in total cellulase activities on China fir, Weeping willow, and Moso bamboo. Trametes vesicolor G20 had a higher level of cellulase than Echinodontium taxodii 2538 during the biodegradation of the same lignocellulose. This resulted in the differences in the cellulose-degrading rate of two white rot fungi. The ligninolytic enzymes, iron-reducing ability and recalcitrance to lignin degradation have the effects on the lignin degradation with white rot fungi. Thirdly, conversion experiments with the cellulase were performed to evaluate the lignocellulose reactivity to cellulase. The reactivity increased during the degradation with white rot fungi. However, the change of reactivity was different in three kinds of lignocellulose. At the first 30-day of biodegradation with Trametes vesicolor G20, the reactivity of China fir had a little increase and the reactivity of Moso bamboo and Weeping willow had a great increase. Accordingly, the cellulose-degrading rate was very low during China fir biodegradation and was very high during the biodegradation of Moso bamboo and Weeping willow at the early stage of biodegradation. Low level of cellulase activity and change of reactivity to cellulase have the effect on the degradation difference during different lignocellulose degradation with Echinodontium taxodii 2538. The cellulase kinetics of lignocellulose degraded and non-degraded was studied using two theoretical approaches. The result showed that the ratio of the efficient cellulose (P) of Weeping willow, China fir and Moso bamboo lignocellulose was increased by 5.94-fold, 5.08-fold and 12.62-fold respectively for Trametes vesicolor G20 and 5.54-fold, 7.74-fold and 15.39-fold respectively for Echinodontium taxodii 2538 compared to the non-degraded lignocellulose after 120-day biodegradation. b value of China fir has only a little change during the biodegradation and P value has little change at the early stage of biodegradation. However, the reactivity constant at the low cellulose concentration (b) of Moso bamboo and Weeping willow have great increases. The result indicated that there was a relationship between degradation difference and the different change patterns of cellulose reactivity to cellulase during biodegradation of different lignocellulose with white rot fungi.Last, Effects of three factors on the cellulose reactivity to cellulase were studied. The result showed that Lignin content of lignocellulose during the biodegradation was mainly correlated to the reactivity. The lignin content was negatively related to the P value by the linear regression analysis. There was no obvious relationship between the initial adsorption capacity and P value. Crystallinity of cellulose has little change during the biodegradation.