Kinetic modeling of thermal inactivation of the Bacillus sp. protease P7.

Data from thermal stability of a keratinolytic protease produced by the Amazon isolate Bacillus sp. P7 was fitted to various mathematical models. Kinetic modeling showed that Weibull distribution was the best equation to describe the residual activity of protease P7 after heat treatment. The effects of temperature on equation parameters and on characteristics of the inactivation curves were evaluated. As expected, faster inactivation was observed at higher temperatures. The critical temperature to accelerate protease decomposition was about 70 °C. The reliable life (t(R)) of the enzyme, analogous to the D value, ranged from 1,824 to 8 min at 45-65 °C. Within these temperatures, an increase of 8.81 °C was needed to lower enzyme t(R) in one-log unit. Protease P7 is a potentially useful biocatalyst for various industrial bioprocesses, and therefore, kinetic modeling of thermal inactivation addresses an important topic aiming enzyme characterization and applications.