Selective Degradation Of Lignin By Synergistic Effect Of Fenton Reaction And White Rot Fungi Fermentation

Crop straw is the most abundant renewable resource of lignocellulose and has high utilization value.However,the difficult degradation of lignin hinders the utilization of cellulose in crop straw.White rot fungi have specific ability to degrade lignocellulose,and Inonotus obliquus has certain selective degradation ability to lignin.As a mild and environment-friendly chemical treatment method,Fenton reaction can destroy the structure of lignocellulose and is beneficial to the biodegradation and utilization of lignocellulose in the later stage.The combination of the two methods may solve the problem of long degradation and fermentation time of single white rot fungi,and may improve the selective degradation ability of white rot fungi,providing a more effective method for the utilization of lignocellulose.In this paper,the effects of Fenton reaction on the selective degradation of lignocellulose,saccharification efficiency,protein production and lignocellulose degrading enzyme activity of wheat straw by Inonotus obliquus solid fermentation were studied.In addition,the effects of pH and Tween-80 on the selective degradation of lignocellulose from bagasse by Inonotus obliquus were studied.The experimental results show that:1.Degradation of wheat straw by fenton pretreatment and Inonotus obliquus solid fermentationThe lignin degradation rate of wheat straw treated with Fenton was 14.7%.In the subsequent fermentation process,the lignin degradation rate of wheat straw was further degraded by Inonotus obliquus.On the 10th day,the lignin degradation rate reached20.9%,which was 27.4%higher than that of single Inonotus obliquus fermentation control,while the degradation rate of cellulose was kept at a relatively low level.The lignin degradation selectivity value and saccharification efficiency of fermented wheat straw treated by Fenton were higher than those fermented by single Inonotus obliquus.On the 10th day of fermentation,the lignin degradation selectivity value was the highest,and the wheat straw treated with co-treatment reached the highest sugar released and sugar yield:227.2mg/g and 32.8%,.Fenton reaction not only shortened the solid fermentation period of Inonotus obliquus,but also improved the selection coefficient and saccharification level.Wheat straw treated with Fenton and then fermented could not only promote the growth of Inonotus obliquus mycelium,but also promote the production of crude protein,and the maximum crude protein yield increased by 2.1 times.It is proved that it is possible to feed wheat straw through the synergistic effect of the two.2.Simultaneous action of Fenton-like reaction with addition of Fe₃O₄ nanoparticles and fermentation of Inonotus obliquusIn this paper,we explored the use of Fe₃O₄ nanoparticles to produce Fenton-like reaction in the process of Inonotus obliquus fermentation,and studied the feasibility of wheat straw lignocellulose degradation by Inonotus obliquus accompanied by Fenton reaction.The results showed that the highest enzyme activity of Mn P was 359.8 IU/g on the 15th day,which was 1.2 times that of the control group.Both Li P and Lac reached the maximum enzyme activity on the 5th day,which was 11 times and 2.5 times higher than that of the control group,respectively,which were 48.6IU/g and 13.4 IU/g,respectively.The main cellulase CMCase and FPase reached the maximum activity on the 25th and30th day,respectively,and the maximum activity was 106.8IU/g and 41.5IU/g,which was5.6 and 8.8 times higher than that of the control group,respectively.The results showed that in the process of fermentation,ligninase played a role first,showing strong enzyme activity,while cellulase showed lower enzyme activity.With the progress of fermentation,the activity of lignase decreased,and cellulase began to play a role with high expression.The results showed that Fe₃O₄ nanoparticles could promote the activity of lignocellulose degrading enzymes of Inonotus obliquus,and Inonotus obliquus had strong selective degradation ability of lignin,especially on the 10th day of fermentation.3.Effects of pH and Tween-80 on degradation efficiency of bagasse by liquid fermentation of Inonotus obliquusThe optimized conditions were as follows:under the conditions of pH6.0 and Tween-800.1%,the lignin degradation rate and selection coefficient reached the best on the second day.The lignin degradation rate of the optimization group was 76.6%,which was much higher than that of the control group(16.8%).The selection coefficient of the optimization group was 2.0,which was greater than 1.5 of the control group.The highest sugar yield and saccharification rate of bagasse fermented for 10 days were 188mg/g and22.8%respectively,while the sugar yield and saccharification rate of bagasse in optimization group were 246.6mg/g and 30.5%respectively,and they were only bagasse fermented for 2 days,which proved that the optimization of pH and Tween80 not only improved the selective degradation level of lignocellulose,but also shortened the fermentation period.This study showed that Fenton reaction and optimization of culture conditions could improve the selective lignin degradation ability of Inonotus obliquus and shorten the fermentation period,which proved the feasibility of synergism between Fenton reaction and Inonotus obliquus.