Influence of lignin and its degradation products on enzymatic hydrolysis of xylan

The influence of lignin, lignin model compounds, and black liquor from the kraft pulping process on the hydrolysis of xylan by xylanase was investigat ed. Addition of vanillic acid, acetovanillone, and protocatechuic acid incr eased the rate of hydrolysis of xylan by as much as 18-50% at low concentra tions, but reached maxims at about 0.05% concentration. Addition of vanilli n caused a 15% improvement in xylan hydrolysis, while addition of guaiacol more than doubled the hydrolysis rate. Increasing concentrations of either lignin or black liquor also increased the hydrolysis rate of xylan. Circula r dichroism spectroscopy indicated a change in the structure of xylanase in the presence of black liquor. (C) Published by Elsevier Science B.V.