Peptidase with Keratinolytic Activity Secreted by Aspergillus terreus During Solid-State Fermentation

The aim of this study was to evaluate peptidase production by Aspergillus terreus in solid-state bioprocess and evaluate its parameters. The best conditions were 5.0 g of wheat bran as substrate, incubation temperature 30°C, inoculum 2.0x10 spores/g and 75% saline volume, with production reaching 677 U/mL (5400 U/g culture medium) after 72 h of fermentation. Biochemical characterization of the crude enzymatic extract showed the optimum pH and temperature of 6.5 and 55°C, respectively. The stability at different temperatures and pH values showed that the extract could endure different pH. The evaluation of the ions influence and inhibitors proved that the enzyme required an ion for better activity, which was corroborated with the inhibition of EDTA and PMSF, characterizing serine and/or metallo peptidase. The extract was also tested for specific activities and showed promising results for keratinolytic and collagenolytic activities (0.252 and 0.165 OD/mL, respectively).