The interactions between lignin and cellulases play an important role in the effective enzymatic hydrolysis of lignocellulosic biomass. Lignin removal has been closely associated with pretreatment efficiency and substrate hydrolysability. However, remarkably we found that organosolv lignins could increase the enzymatic hydrolysis of Avicel and pretreated biomass. In this study, we quantified the effects of softwood and hardwood organosolv lignins (EOL) on enzymatic hydrolysis of Avicel based on the initial hydrolysis rate and the 72-h hydrolysis yield. Organosolv lignins were collected from ethanol organosolv pretreatment of Cottonwood, Willow, Aspen, Eucalyptus and Loblolly pine. It was observed that organosolv lignins from Cottonwood, Willow and Aspen improved the 72-h hydrolysis yield by 5-13%, while organosolv lignins from Eucalyptus and Loblolly pine decreased the 72-h hydrolysis yield by 13% and 6%, respectively. Interestingly, EOL from Cottonwood increased the 72-h hydrolysis yield from 61% to 68% under 5 FPU. On the contrary, EOL from Eucalyptus decreased the 72-h hydrolysis yield from 61% to 53%. The initial hydrolysis rate (1.11 g/L/h) was less affected by the addition of organosolv lignins. Furthermore, we examined the functional groups and structural features of these organosolv lignins by <sup>1</sup>H and <sup>13</sup>C NMR. Our results suggested the organosolv lignins from hardwood play distinct roles in enzymatic hydrolysis of lignocellulsoic biomass and understanding their distinctive structures has great potential to improve the effectiveness of enzymatic hydrolysis.

Positive role of lignin in enzymatic hydrolysis of lignocellulosic biomass

249th National Meeting (2015)

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