Continuous hydrolysis of pullulan using covalently immobilized pullulanase in a packed bed reactor

Pullulanase covalently immobilized on Duolite XAD761 has been used for developing a continuous flow reactor for the hydrolysis of pullulan. Packed bed reactor containing 34.10 U of immobilized biocatalyst with feeding of pullulan solution (0.44%, w/v) at a flow rate of 5 mL h−1 supported maximum pullulan hydrolysis at 60 °C. The reactor was run continuously for 32 days and immobilized biocatalyst lost half of its original activity after 31 days of continuous operation at 60 °C. The volumetric productivity and yield of reducing sugars were 3.38 ± 0.02 g L−1 h−1 and 4.40 ± 0.01 mg mL−1, respectively during the beginning of the hydrolysis. The developed immobilized biocatalyst has shown good operational and mechanical stability and can be successfully used for the hydrolysis of pullulan in a continuous system. Literature survey reveals no report on continuous hydrolysis of pullulan using whole cells or immobilized enzyme.