Purification of a bacterial pullulanase on a fluidized bed of calcium alginate beads

Pullulanase from Bacillus acidopullulyticus was purified on a packed bed and a fluidized bed of calcium alginate beads. The binding of enzyme activity to the medium was found to follow Langmuir isotherm pattern. The maximum binding capacity was 1476 U ml⁻¹ matrix and the dissociation constant was 142 U ml⁻¹. The dynamic binding capacities at 5% breakthrough in the packed and fluidized beds were 472 U ml⁻¹ and 644 U ml⁻¹, respectively. In the packed bed as well as the fluidized bed, an activity recovery of more than 95% with fold purification in the range of 46–59 was observed. The elution with a competitive inhibitor, viz. maltose, and high-fold purification indicate an affinity-based process. The purification process worked equally well with columns of bed volumes of 3.8 and 10 ml.