Effects Of Lignin From Corn Stover On Hydrolysis And Adsorption Behavior Of Cellulase

In plant cell,lignin accounts for 15%-30% wt of lignocellulosic biomass,and may even exceed 40% in the pretreated biomass.The presence of lignin can cause steric hindrance to cellulose,influencing the availability of cellulase to cellulose,or produce non productive adsorption with cellulase,and even inactivat enzymes.Therefore,it is very important to investigate the effects of different lignins on cellulase adsorption and hydrolysis for understanding how to reduce the amount of cellulase in the hydrolysis and cut the overall cost of conversion of lignocellulosic materials.In this paper,acid insoluble lignin(AIL)was used to explore the effect of lignin addition on cellulose hydrolysis.The results showed that AIL had no effect on the the initial 30 minutes of enzymatic hydrolysis and exhibited inhibitory effect around 12 h The inhibiton raised from 5% to 30% with the increase of lignin content.With the addtion of 1 and 10 mg/g AIL,the maximum adsorption capacity of Avicel reduced from 276.9 mg/g to 179.7 and 112.1mg/g,respectively.While the present of 100 mg/g AIL would break the adsorption model of cellulase on cellulose,and increased the total adsorption of lignin and Avicel in slightly.To further explore the effects of hydrolysis residues in the next step of the new lignocellulosic materials hydrolysis,the enzymatic hydrolysis lignins(ERL)were isolated from milled,alkali and acid pretreatment of corn stover.The experiment showed that the adsorption of cellulase on these three kinds of ERL were 87-117 mg/g,but ERL had few effect on the adsorption and hydrolysis of cellulase on cellulose(2%).When the concentration of cellulose increased to 5%,ERLs from alkali and acid pretreatment showed obvious inhibitory effect on hydrolysis(13%-29%).Moreover,the cellulase adsorbed on the ERLs can be desorbed and still active,which shown that the adsorption of enzyme on ERLs was not the main reason for the inhibition of ERLs.The dilute acid extraction was used to further remove the sugars from ERLs and the residuals(AERLs)were used to study their effects on the hydrolysis and adsorption of cellulase.The AERLs from acid and alkali pretreatment inhibited the hydrolysis of cellulose with different concentrations,while the AERL from milled did not.Moreover,the adsorptioncapacity of three kinds AERLs to cellulase decreased greatly(50-23 mg/g),but still had little effect on the amount of cellulase absorbed on cellulose.The adsorption of cellulase on AERLs still could desorbed,and the desorption supernatant and residues were still had hydrolysis capacity.The reason for their inhibition should be that the hydrophilicity of lignin increased resulting in the adsorption of AERLs on cellulose,thus infulenced the hydrolysis efficiency.