Comparison Of Submerged And Solid State Pretreatment Of Peanut Shell By Inonotus Obliquus:Degradation Model、Lignocellulolytic Enzyme Production And Saccharification

Peanut shell is a renewable biological resource,composed of lignin,hemicellulose and cellulose.However,the utilization rate of lignocellulose in peanut shell is very low,which is mainly due to lignin encapsulates cellulose and hemicellulose led to cellulosel difficult to be used.White rot fungi is of high value in biological pretreatment of lignocellulose,and it is the only fungus that can directly degrade lignocellulose to CO₂ and H₂O.Inonotus obliquus also belongs to white rot fungus.This paper reports a comparative study of different cultivation systems（submerged fermentation,SmF and solid state fermentation,SSF）on peanut shells,this paper investigates changes of lignocellulose structure,and saccharification efficiency of treated peanut shells,based on which indicates the degradation rule of lignocellulosic on peanut shells,the rule of enzymatic changes and the utilization rate of cellulose of different cultivation systems.This paper uses the chemical analysis named van Soest method to analyze the dynamic degradation rate of lignin,cellulose and hemicellulose in peanut shell.During the process of lignocellulose degradation,chemical structure,degree of crystallinity and surface structure were characterized by using Fourier transform infrared spectroscopy（FTIR）,scanning electron microscopy（SEM）,X-ray diffraction（XRD）.We studied the relationship between lignocellulosic degradation enzyme and lignocellulose degradation efficiency of different cultivation systems（SmF and SSF）on peanut shells.Through the saccharification experiment,we compared the utilization rate of cellulose different cultivation systems（SmF and SSF）on peanut shell.Experiments results show that:1.Comparison of peanut shell degradation mode:After 12 days of fermentation,the degradation rate of lignin in solid and liquid fermentation was 62.11%and 33.86%respectively,the degradation rate of hemicellulose was 58.5%and 45.04%respectively,the degradation of cellulose was 57.69%and 28.29%respectively.In liquid fermentation of peanut shells the degradation rate of lignin less than the degradation rate of cellulose,without selective degradation;for the solid fermentation of peanut shells the degradation rate of lignin is always more than the degradation rate of cellulose in whole fermentation period,with selective degradation.2.Chemical composition,surface structure,cellulose crystallinity change:By the ratio of characteristic peak of lignocellulose in FTIR,determining the degradation rate of lignin,cellulose and hemicellulose in different cultivation systems（SmF and SSF）,Further determining of Inonotus obliquus solid fermented peanut shell has a certain selectivity.The result of XRD showed the crystallinity of lignocellulose had a certain degree of decline in Inonotus obliquus solid fermentation and liquid fermentation on peanut shells in whole fermentation period.In the liquid fermentation and solid fermentation,the crystallinity of lignocellulose was reduced from 50.3%to 40.66%and 43.67%respectively.The result of SEM showed various cracks,holes,faults and degradation areas on the peanut shell surface in Inonotus obliquus solid fermentation and liquid fermentation.The degradation of lignocellulose in peanut shell by Inonotus obliquus was verified.3.The production rule of lignocellulosic degradation enzyme:The highest enzymatic activity of LiP and MnP in liquid fermentation were 1532.26 U/g,2038.46U/g was 4.52 and 4.48 times when compared to solid fermentation.The enzymatic activity of MnP is higher than LiP in SmF and SSF.Lignin enzymes was produced in the early fermentation,and the lignin enzyme of liquid fermentation was produced earlier than solid fermentation.This may be associated with the structure of lignocellulose,lignin is surrounded by cellulose,first to break the lignin package,so lignin enzymes activity was high in the early fermentation period.The cellulose enzyme of liquid fermentation was produced higher than solid fermented.The highest enzyme activity of FPA and CMC was 5.28 U/g and 22.6 U/g in liquid fermentation,which was 1.1 and 1.8 times that of solid-state fermentation.The enzymatic activity of FPA and CMC was the highest in the late fermentation.But the production rule of enzymes presented some differences in liquid fermentation and solid fermentation.The change trend ofβ-glucosidase in liquid fermentation and solid fermentation was different,the highest enzymatic activity ofβ-glycosidase enzyme was 22.2 U/g in liquid fermentation,which was 2.2 times that of solid-state fermentation.Changes in the fermentation process were also different.The enzymatic activity ofβ-glucosidase in liquid fermentation first increased and then became stable,it reached maximum in eighth day and the rest day was low in solid fermentation.It was almost no enzymatic activity in early period of solid fermentation.4.Saccharification efficiency:The saccharification experiment was used of Inonotus obliquus crude enzyme.We found that saccharification efficiency of treated peanut shells was always decreased in the liquid fermentation.The total sugar content of the peanut shells after saccharification was reduced from 104.59mg/g to 49.68mg/g in the whole period of fermentation.The total sugar after the saccharification of peanut shells rose from 104.59mg/g to 119.9mg/g in the solid fermentation.In early stage of fermentation,the rate of lignin degradation was less than cellulose,while the rate of cellulose degradation was less than lignin in late stage of fermentation,most of cellulose was degraded,so the total sugar was always decreased.The rate of lignin degradation was greater than cellulose in solid fermentation,so the total sugar was always increased.We come to the conclusion that the liquid fermentation of peanut shells to the generation of lignocellulose degradation enzyme,the peanut shells of lignocellulose degradation rate is high,but it is not good for the saccharification and utilization of cellulose in peanut shells;Solid fermentation is beneficial to the utilization of cellulose in peanut shells.