Study On The Enzymatic Saccharification And Thermogravimetry Of Corn Stover Pretreated By Mixed-culture Of White-rot Fungi

Cellulosic ethanol production from corn stover offers significant economicopportunities. However, rate of enzymatic saccharification in corn stover is not well due tocomplex structure of lignocellulose. So, pretreatment of corn stover is necessary. Theobjectives of this research were to establish mixted cultures of white rot fungi for thepretreatment of corn stover, and to evaluate the rate of enzymatic saccharification andthermogravimetry (TG) of corn stover.Corn stover was degraded by mixed-cultures according to different combinations of22 strains screened from 157 stains. The results showed that the rate of enzymaticsaccharification was not significant improvement. Further study on the mechanism of lowrate of saccharification in mixed-culture of three fungi was analyzed. The results showedAuricularia/ Stereum and Auricularia/ Irpex mixed-culture systems were establishedsuccessfully by adjusting the proportion or patterns of cultivation. Inadditon,characteristics of enzyme and lignocellulose degradation of white rot fungi werereaserched. The main conclusions were the following:There were significant changes in enzyme activities during the mixed-culturecompared with pure cultures, which demonstrated synergy or inhibition; cellulosedegradation rate by mixed culture was enhanced, lignin degradation rate changed betweenthe two pure cultures; Owing to the combination of different strains, hemicellulose showeddifferent degradation rate trends. Enzymes activities had no correlation with lignocellulosedegradation rate. Saccharification rate of mixed culture was lower than the pure cultureswhich may be expained by a decline in cellulose content and lignin reservation.TG experiment indicated that corn stover pretreated by white-rot fungi led to theinitial pyrolysis temperature decreased, an increase in termination temperature and thesolid residue, and showed no significant differences with pure culture. From the activationenergy, the mixed culture than pure cultures is not conducive to carry out pyrolysis. Thiscould be explained by a decline in the relative content of cellulose and lignin contentrelatively increased.The study provided a theoretical basis for application of mixed-culture in biomassproduct of fuel ethanol and bio-oil.