Energy Plant Cell Wall Structures And Their Digestibility With Alkaline Pretreatments

Concerns about energy crisis and globe warming have been seriously raised over the world. Biomass utilization is increasingly considered as a practical way for sustainable energy supply and long-term environment care around the world. Lignocellulose is the most abundant renewable biomass on the earth and is the major component of the plant cell walls. Understanding of cell wall molecular structure is important for Biomass pretreatment and Bioethanol production. In this study, Miscanthus (C4) and Rice (C3) were used:o analyze their cell wall composition and digestibility upon NaOH pretreatment and subsequent enzyme degradation.The plant cell walls are composed of cellulose, hemicelluloses, lignins and pectins. The results showed that total lignin contents were most varied among the tested samples of miscanthus. M.floridulus samples were not much altered in the contents of the hemicelluloses and cellulose, whereas M.lutarioriparius showed a little change in hemicelluloses. As a comaprison, rice samples are greatly changed only in the hemicellulose contents.With the increased concentrations of NaOH, most samples (Hexose of pretreatment, Pentose of pretreatment & Hexose of enzymolysis) in Miscanthus appeared to have a significantly elvated degestibility of biomass. One sample (Pentose of enzymolysis) can reach to the highest activity at 1% NaOH among the M.floridulus, and two samples (Hexose of enzymolysis and Pentose of enzymolysis) showed much higher biomass degradation than others in M.lutarioriparius. Only three rice samples (Pentose of pretreatment, Pentose of pretreatment & Pentose of enzymolysis) showed high degradation efficiency.In addition, we analysed the relationship between the plant cell wall composition and the efficiency of biomass pretreatment and enzymolysis. It is characterized that lignins are the major factors for biomass degradation in M.floridulus, and hemicelluloses and lignins both played an important role in M.lutarioriparius. As a difference, hemicelluloses are the crucial factors for biomass degradation in rice.In Miscanthus, the S monomer of lignins is the key factor inhibiting enzyme degradation, and the non-crystalline cellulose could result in an increased efficiency of the biomass digestion.