Adsorption and reuse of cellulases during saccharification of cellulosic materials

Adsorption characteristics of cellulases onto cellulosic materials such as potato pulp (waste from potato starch industry) were studied and compared with the adsorption onto Avicel (microcrystalline cellulose). We investigated the adsorption of cellulases as a means of determining the minimal enzyme loading for hydrolysis and recycling of enzymes. Most of the enzymes were rapidly adsorbed onto the substrate within the first 10 min of contact at 30°C. Temperature had no significant influence on the adsorption behaviour of cellulases in the range of 10–30°C. The amount of adsorbed activities increased with increasing enzyme concentration up to a loading of 50 units per g substrate. The enzyme loading at which saturation of substrate occurs correlated with the optimum loading for hydrolysis, thus indicating that the adsorption process controls the rate of hydrolysis. It was observed that more than 40% of the cellulase adsorbed onto the unhydrolyzed residue after hydrolysis, whereas the rest of the enzyme remained in the hydrolysate. Some simple methods were examined for effective recovery and recycling of these enzymes.