Single method of purification for endoglucanase from Aspergillus niger by polyelectrolyte precipitation

Abstract

The precipitation of endoglucanase from Aspergillus niger with synthetic and natural electrically charged polymers -poly vinyl sulfonate (PVS) and chitosan (CHS)- was characterized and applied to a simple method of purification of an enzymatic extract obtained from fungal culture under solid-state fermentation (SSF).The kinetics of complex formation was determined. The results of the kinetic profile obtained for CHS and PVS indicated an exothermic mechanism for the formation of the non-soluble complex. CHS exhibited a marked stabilizing effect on endoglucanase.The enzyme precipitated successfully with both polymers. The precipitation method applied to commercial endoglucanase and the fungal extract showed similar patterns with high purification factors. The recovery of the activity in the re-dissolved precipitate from the fungal extract was close to 40% at pH 5.3 using PVS (1% w/w) as precipitating agent and the purification factor was near 9. The purification factor of endoglucanase in the precipitate of the enzymatic extract from SSF with CHS (0.05% w/v) was around 7. These parameters make this precipitation method appropriate to be included in the last stages of a downstream process, with advantages such as simplicity, scalability and ability to concentrate and stabilize the enzyme.