Isolation Of Lignin-degrading Strain And Enzymatic Hydrolysis Of Corn Stover

In this study,strains of lignin-degrading fungi were isolated from natural decay and decayed corn stover from different latitude and longitude of Jilin Province by using guaiacol and aniline blue culture medium.The strains were identified by morphological screening followed by the phylogenetic analysis of ITS sequences deciphering the taxonomic status of the strains.Through the analysis of the activity of extracellular ligninase produced during the solid-state fermentation of corn stover,the most efficient stover-degrading fungi were selected.The objective of this study was to screen the strains of lignin-degrading fungi and study their the activity of lignin-degrading enzyme using corn stover as substrate.In this study,an efficient corn stover degrading strain of fungus was isolated and identified as W2.The isolated strain exhibited higher activity of peroxidase and laccase during the degradation process.As well as the degradation of lignocellulose,the relationship between ligninase activity and the change of straw composition,and the orthogonal experiment was optimized by orthogonal test to achieve the best enzyme activity at low cost.1.Through morphological and ITS sequence analyses,a highly efficient corn stover degrading fungus was isolated and named as W2(Irpex lacteus W2).2.The results showed that the manganese peroxidase produced in 4–8 d showed an ascending trend,and reached the peak value of 86.31 U/mL at 8 d which was 88.20% higher than that of Phanerochaete chrysosporium(P<0.01).The laccase activity of this strain was higher than that of Phanerochaete chrysosporium(45.86 U/mL),and reached 20.60 U/mL at 8 d,which was 40.76 % higher than the control(P<0.05).3.In order to analyze the morphological changes of the surface of maize straw before and after fungi treatment,observed by electron microscopy to observe the results of the picture,The results of the SEM can be seen that the Irpex lacteus W2 can reduce the crystallinity of the phloem of the straw significantly.4.In order to analyze the components changes of the straw after treatment with different fungi,the chemical separation of the straw components,calculate the contents of cellulose,hemicellulose and lignin in the straw before and after the treatment of fungi.The results are shown the lignin selectivity in the process of degrading the straw was 22.9544% of the total weight loss rate.5.In order to obtain the best culture formula,the L9(33)orthogonal test was designed.The inoculation amount of the fungus is 2,the mass ratio of the liquid / solid is equal to 5,the initial pH was 6,and the highest MnP activity was reached.In the straw inoculation amount of 5,liquid mass ratio is equal to 3,the initial pH of 7,this time reaches the highest Lac activity.And by adding a small amount of Fe2+ in the medium,the two enzymes have a gain effect.