Gene Structure and Expression Author Index

Abstract

This paper investigates the influence of polyethylene glycol (PEG) molar mass, concentrations of PEG and sodium citrate, and pH, in situ recovery on protease produced by Aspergillus tamarii URM4634. A biochemical characterization study was conducted, and thermodynamic parameters were determined in the test which used 8000 (g/mol) PEG molar mass, PEG concentration 24% (w/w), sodium citrate concentration 20% (w/w) and pH 6.0 with partition coefficient of 35.0, activity yield of 98.4 and concentration factor of 2.14. This PEG-phase had an optimum pH and temperature of 8.0 and 60 °C, respectively, being inhibited by EDTA (83.3%) which indicated that this's a metalloprotease. The thermodynamic studies of the protease had an activation energy of 19.01 kJ/mol and a deactivation energy of 29.6 kJ/mol. It was in this range that the following estimates could be made: enthalpy of ΔH*d 29.7 kJ/mol, entropy of ΔS*d − 265.0 kJ/mol K and Gibbs free energy of 120.0 ≤ ΔG*d ≤ 125.9 kJ/mol. These results show a possible scaling-up of the bioreactor process which, under the conditions in the shaker flask, showed considerable values in the integrated production and extraction process, thus demonstrating the potential of this process for obtaining a high recovery of protease and similar products.