Characterization Of Lignin Composition And Structure That Affect Biomass Degradability In Energy Plants

High demands for fossil energy and concerns over global climate change have led to the pursuit of alternative energy. Biofuel use is a promising solution to reducing of petroleum consumption. There is a great interest in using cellulosic plants, also called energy plants, as renewable raw materials for bio-energy. Cellulosic biomass is very difficult to break down into sugars because of the presence of lignin in the plant cell walls. Lignin, a major component of the plant cell walls, has long been recognized for its negative impacts.Over the last two decades, one has made great efforts in terms of the relationship between lignification and digestibility. Because of the complexity of plant cell wall structures, however, the mechanisms of cellulose degradation are poorly understood.Lignin in grasses is composed primarily of p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) units. There are different results in the different articles about the effects of the ratio of S and G units in lignin. In this work, we analyzed the lignin units of Miscanthus floridulus (CQM4,CQM5,CQM6), Triarrhena lutarioriparia (CQM1,CQM2, CQM3), wheat(CQW1,CQW2,CQW3) and rice (CQR1,CQR2,CQR3). No significant changes in cellulose, hemicelluloses, and lignin were observed in Miscanthus floridulus, Triarrhena lutarioriparia, wheat and rice, but the ratio of the S/G varied from0.29 to 0.77,0.36 to 0.66,0.39 to 0.82 and 0.77 to 0.92 respectively. These materials were hydrolyzed with (1.0%) H2SO4 and (1.0%) NaOH pretreatment and enzymolysis. The results indicated that S/G ratio significantly affected the yield of sugar, and the higher was associated with a lower syringyl/guaiacyl (S/G) ratio.