Effect of Residual Lignin on the Cellulase Hydrolysis of Bamboo Residues Pretreated with Phenoxylethanol Coupled Acid/Alkali
In this study,bamboo chips,the residue of bamboo processing,were used as the object to investigate the structural characteristics and physicochemical properties of residual lignin in bamboo chips pretreated by phenoxylethanol coupled with acid/alkali solutions.The non-productive adsorption mechanism of residual lignin on cellulase in different pretreated bamboo chips was revealed using fluorescence spectroscopy and surface plasmon resonance techniques.The results indicated that as the increases of V(phenoxylethanol)∶V(acid/alkali)ratio,the cellulose hydrolysis yield of pretreated bamboo chips increases from 9.39％to 67.38％/49.87％.Characterization of residual lignin revealed an increase in the syringyl/guaiacyl(S/G)ratio of lignin in pretreated bamboo chips as the temperature and the V(phenoxylethanol)∶V(alkali)ratio increase,and the lignin molecular weight was more uniform.The characterization results of 2D-HSQC NMR,31P NMR,surface charge and hydrophobicity indicated that the inhibitory effect of lignin on cellulose hydrolysis was directly proportional to its phenolic hydroxyl content,hydrophobicity,and Zeta potential.Fluorescence spectroscopy and surface plasmon resonance techniques suggested that the primary driving force types for lignin-cellulase interaction were related to pretreatment temperature,phenoxylethanol volume,and acid/alkali solution volume.The affinity of lignin and cellulase from different pretreated bamboo chips was different.Among them,the highest affinity observed in pure phenoxylethanol pretreated bamboo chips,followed by pure acid/pure alkali solution pretreated lignin,and the lowest affinity was observed in phenoxylethanol and acid/alkali coupled pretreated bamboo chips.
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