Recovery of cellulase enzymes by countercurrent adsorption

The cost of enzyme production accounts for as much as 60% of the total cost for enzymatic hydrolysis of glucose. The purpose of this study was to evaluate countercurrent adsorption as a means of recovering enzyme from hydrolyzate. Results from adsorption studies and hydrolysis experiments were used to design a system for enzymatic hydrolysis of steam exploded corn stover operated with two stages of countercurrent adsorption. The effects of temperature, enzyme loading, and pretreatment on the adsorption of cellulase enzymes were studied. Steam explosion is superior to acid treatment and Wiley milling in increasing the susceptibility of the substrate to enzymatic attack. Glucose yields as high as 94% are achieved by enzymatic hydrolysis of steam exploded corn stover. High conversions permit release of enzyme so that it may be recovered from the liquid. The glucose yield decreases with increasing solids concentration. A 10 wt % suspension of steam exploded corn stover was hydrolyzed with an enzyme loading of 25 FPU/gm at 45/sup 0/C for 24 hours. Enzyme in the hydrolyzate was recovered by two stages of countercurrent adsorption, each stage operated at 25/sup 0/C for 45 minutes. The make up enzyme requirement, measured as filter paper activity, was 35% ofmore » that required for the control experiment. A preliminary economic evaluation showed that the enzyme production cost can be reduced by 61% if enzyme is recovered by countercurrent adsorption.« less