Abstract
Understanding of the amount of free cellulase or unrecoverable cellulase adsorbed on residue during enzymatic saccharification is important to recycle cellulase. As one example, cellulase adsorption behavior was tried to be explained when steam-exploded eucalyptus was saccharified with 51 FPU of cellulase cocktail per g-dry substrate for 2 to 16 hours. Cellulase adsorption onto the substrate was maximum at 2 h. The amount of adsorbed cellulase was gradually decreased, and then finally tended to be constant. The behavior is similar to that for enzymatic saccharification of the mixture of Avicel and lignin powder. It was estimated that cellulase was adsorbed onto both cellulose and lignin to their saturated adsorption capacity, and cellulose-adsorbed cellulase was liberated to liquor as cellulose is decomposed. The method to predict cellulase adsorption capacity of lignin in substrate by extrapolation to zero content of polysaccharide in the residue was proposed. In this study, about 30% of the loading cellulase seemed difficult to be recovered because of adsorption onto steamexploded lignin.
