Screening And Enzymatic Proteomics Analysis Of Poplar Lignocellulose Degrading Fungus T7

Lignocellulose is a raw material with great potential for biomass energy due to its rich resources.However,due to its complicated structure,it restricts the efficient degradation of lignocellulosic raw materials and hinders its development into new energy sources such as biofuels.At present,fungi are one of the most important lignocellulose-degrading microorganism.In this study,poplar is used as the degradation raw material to screen the fungi that can degrade lignocellulosic of poplar,from which a highly efficient degradation strain(T7)is isolated and identified,and the characteristics as well as proteomics of enzyme production by the strain T7 were studied,laying a foundation for further study.The main results are as follows:1.Screening and identification of lignocellulose degrading fungiCollected rotten wood in the wild,24 individual colonies were isolated and purified.After preliminary screening by Congo red-CMC medium plate,PDA-aniline blue medium plate and PDA-guaiacol medium plate,six strains with good color rendering effect on qualitative medium were selected in the liquid medium with poplar as the sole carbon source,and the ligninase activity in the fermentation supernatant was measured.The cellulase activity of strain T7 was the best among the six strains.The endoglucanase activity reached a maximum of 2338.28 U/L on the 6th day,and the total cellulase activity reacheda maximum of 680.71 U/L on the 4th day.β-glucosidase activity reached a maximum of 1040.62 U/L on the 6th day.The strain T7 lignin peroxidase activity reached the maximum value of 896.06 U/L on the second day,the manganese peroxidase enzyme activity reached 945.06 U/L on the sixth day,and the laccase activity reached the maximum on the 10th day value 5268.67724 U/L.According to morphological observation and ITS sequencing identification,T7 was known as Peniophora incarnata.2.Degradation characteristics of poplarThe degradation of poplar by strain T7 in liquid fermentation was studied.The strain T7 was fermented by liquid fermentation with poplar as the sole carbon source.The biomass and weight loss of strain T7 were measured in 7 days.At the 7th day,the biomass of strain T7 was 3.174 g/L,and the weight loss rate of poplar reached the highest of 6.95%.From the change curve,we can know that the weight loss rate of poplar increases with the increase of strain T7 biomass,which is positively correlated.The composition of poplar wood fiber was determined by Van Soest and the degradation rate was calculated.The results are as follows:cellulose degradation rate was 10.63%,lignin degradation rate is 5.23%,hemicellulose degradation rate was 2.34%.The surface structure of poplar treated by T7 strain was observed by SEM and FTIR.The results showed that the structure of poplar after strain T7 treatment had significant changes.3.Enzyme-producing proteomics of strain T7Under inorganic nitrogen source,glucose and poplar were respectively used as carbon source to culture strain T7.The biomass of strain T7,the protein concentration in fermentation supernatant and the enzyme activity related to lignocellulose degradation were measured.The results showed that biomass,protein concentration in culture supernatant and the activities of endoglucanase,totalcellulase,β-glucosidase,lignin peroxidase,lignin manganese peroxidase and laccase in supernatant were higher than those in glucose.TMT labeled Nanolc-MS/MS was used to analyze the secretory proteome of strain T7.651 proteins were isolated and identified from the culture supernatant of poplar as carbon source and glucose as carbon source.Among them,137 proteins belonging to CAZy active enzyme were significantly down regulated in the culture medium of glucose as carbon source.These results indicated that poplar significantly promoted the production of lignocellulase.