Structure characterization and inhibitory effect of lignin from the outer and inner layers of bamboo after alkali pretreatment

In this work, structural changes and inhibitory effects of lignin from the outer and inner layers of bamboo after alkali pretreatment were investigated. The results revealed that the carbohydrates contents in lignin samples from bamboo outer and inner layers decreased from 22.2% and 21.4 to 10.1% and 10.4% by alkali pretreatment, respectively. Alkali pretreatment could increase the molecular polydispersity index and syringyl/guaiacyl ratio of lignin, decrease lignin molecular weights and cleave the esterified p-coumarate in bamboo lignin. Inhibitory effect of bamboo lignin on cellulose hydrolysis decreased after alkali pretreatment, which could be explained by the lower adsorption capacity of lignin toward cellulases after alkali pretreatment. These findings discovered the structure of alkali pretreated bamboo lignin and enhanced the understanding of the mechanism of alkali pretreatment in increasing enzymatic hydrolysis of bamboo.