Protease-based cross-linked enzyme aggregates with improved catalytic stability, silver removal, and dehairing...

Proteases have gained special research place due to their broader activity spectrum and applied perspectives for different industrial sectors. The present research focused on three aims, i.e., (1) to identify the best protease producer strain among three different Aspergillus strains, (2) the development of protease-based cross-linked enzyme aggregates (CLEAs) and (3) silver removal and dehairing potentialities of developed CLEAs. A. flavus gave optimum activity (98.50 U/mL) with the culture conditions (pH -7.5, 35 °C, inoculum 2.5 mL and fermentation time 48 h) by applying RSM under CCD. The protease-CLEAs were developed with recovery activity (37.45%) by optimizing conditions through RSM under CCD (80% ammonium sulfate, 65 mM glutaraldehyde, and 0.15 mM BSA). The adequacy of the model was checked by ANOVA, and the interactions among different variables were plotted using 3-D graphs. The characterization profile revealed high pH and thermal stability at pH -9 and 60 °C, respectively. The kinetic study revealed lower K_M and higher V_max values (31.02 μM and 91.16 U/mL, respectively) after CLEAs formation, as compared to the free protease (61.42 μM and 84.45 U/mL, respectively). By applying on X-ray film and animal hides, protease-CLEAs showed the best activity with minimum time as compared to free protease.