Study On Influencing Factors And Mechanisms Of Cellulose Biologically Saccharification In Apple Pomace

Effects of microbiological pretreatment with white-rot fungi and brown-rot fungi on the degradation were studied; then, the UA8Aspergillus Niger and Trichoderma reesei were used to investigate the role of the saccharification strains on cellose degradation. Correlated composition content of reducing sugar, cellulose, hemicelulose, lignin and the activity of related enzymes of celluases were measured throughout pretreatment/sarcchrificatione to eliciate the biological mechanism of each process. Finally, single factor experiment and response surface test were conducted to optimize parameters for saccharification. Main results are as follows:(1) As the pretreatment strains, the white-rot fungi and brown-rot fungi played a catalytic role on subsequent saccharification. Cellulase was used to degrade the pretreated pomace, the reducing sugar production of pomace that pretreated by white-rot fungi is200.22g/kg, the production of pomace that pretreated by the brown-rot fungi is143.699g/kg, which increased81.83%and30.5%respectively in comparision with control. The two strains can also saccharify the pomace directly. The brown-rot fungi saccharified earlier than the white-rot fungi, after12days, the effects of saccharification by the two strains was almost the same. Compared with the control, after15days, the reducing sugar content of the white-rot fungi and the brown-rot fungi has increased100.677g/kg and99.703g/kg respectively.(2) Accoding to the changes of each costituent content, lignin and hemicellulose were degraded firstly by the white-rot fungi, then cellulose was degraded rapidly in the late preatment period; cellulose and hemicellulose were always degraded by the brown-rot fungi. The laccase that secreted by the white-rot fungi degraded a large amount of lignin; the brown-rot fungi secreted mainly cellulase and hemicellulase which degraded a lot of cellulose and hemicellulose. Both of the removal of lignin and cellulose structural changes will facilitate later happened saccharification, moreover, the removal of lignin worked better.(3) The UA8Aspergillus Niger and Trichoderma reesei were used as the saccharification strains; we found that there was a close relationship between reducing sugar and cellulose. Exo-β-1,4-glucanase and endo-β-1,4-glucanase played an important role in the former phase of saccharification; the β-1,4-glucosidase played an important role in the later phase of saccharification.(4) The UA8Aspergillus niger and Trichoderma reesei were used as the saccharification strains, optimum Saccharification conditions were detected as follows:urea1.5%, the solid-liquid ratio1:2.5, natural pH(pH4.9), temperature26℃, Trichoderma reesei:UA8Aspergillus niger3:1, sorbitol1%, inoculated with Trichoderma reesei48h, and then inoculated with UA8Aspergillus niger, saccharified5days.(5) Through the orthogonal design, regression analysis and response surface analysis, optimum process parameters were determined as:sorbitol1%, urea1.53%, inoculated with Trichoderma reesei43.08h, and then inoculated with UA8Aspergillus Niger.(6) Using the selected process parameters to repeat saccharification, we found that repeating three batches of saccharification, the reducing sugar production was335.74g/kg, and saccharification rate was about33.57%.