Column cellulose hydrolysis reactor: the effect of retention time, temperature, cellulase concentration and exogenously added cellobiase on the overall process

Summary

A novel column cellulose hydrolysis reactor with constant enzyme recycling was operated under various conditions to determine the effects of retention time, temperature, cellulase concentration and exogenously added cellobiase on the concentration of the product stream and the productivities of the reactor. Short term (7 days) hydrolysis was best at 42°C while longer term (14 days) hydrolysis was better at 37°C. A retention time of 11 h and reactor cellulase concentration of 30 filter paper units per gram of cellulose gave the best compromise for efficient operation by minimizing product inhibition, maximizing product concentration and minimizing enzyme consumption. The addition of cellobiase to the reactor increased cellulose hydrolysis and raised the proportion of monomeric sugars in the hydrolysate. Continuous cellulose hydrolyses were maintained for 7 and 14 days at 42°C and 37°C, respectively, resulting in volumetric productivities of 6.82 and 4.84 g/l/h and average sugar concentrations of 7.3% and 6.0% (w/v), respectively. Greater than 95% (w/w) of the sugars produced were in the monomeric state. Average cellulase used for the two runs were 8.4 and 5.3 filter paper units per gram of sugar produced, respectively.