Direct quantitative determination of adsorbed cellulase on lignocellulosic biomass with its application to study cellulase desorption for potential recycling

摘要

Effective hydrolysis of pretreated lignocellulose mediated by cellulase requires an in-depthnunderstanding of cellulase adsorption and desorption. Here we developed a simple method forndetermining the adsorbed cellulase on cellulosic materials or pretreated lignocellulose, whichninvolves (i) hydrolysis of adsorbed cellulase in the presence of 10 M of NaOH at 121 u0002nC for 20 min,nand (ii) the ninhydrin assay for the amino acids released from the hydrolyzed cellulase. The majornlignocellulosic components (i.e., cellulose, hemicellulose, and lignin) did not interfere with thenninhydrin assay. A number of cellulase desorption methods were investigated: pH change as well as thenuse of detergents, high salt solution, and polyhydric alcohols. The pH adjustment to 13.0 and thenelution by 72% ethylene glycol at neutral pH were among the most efficient approaches for desorbingnthe adsorbed cellulase. For the recycling of active cellulase, a modest pH adjustment to 10.0 may bena low-cost viable method to desorb active cellulase. It was found that more than 90% of cellulasenfor hydrolysis of the pretreated corn stover could be recycled by washing at pH 10.0.