Calorimetric on-line monitoring of proteolytic activity of P.aeruginosa cultivated in a bench-scale biocalorimeter

Abstract

The aim of this work is to generate thermokinetic data for the production of proteases which would be immensely useful not only for successful scale up of a ferementor for protease production but also to monitor and control of the process by following the heat signals. The biocalorimetric studies prove that the protease production and heat generation profiles are comparable. Oxygen uptake rate was found to correlate well with both biomass growth and heat production rate at all lag, exponential and stationary growth phases. Heat yield due to biomass growth (anabolic) related reactions and substrate uptake (catabolic) related reactions were estimated from the calorimetric experiments and the results were analyzed. Crude protease secreted in calorimeter was extracted separately and characterized by Zymogram and SDS-PAGE analytical techniques. The protease was found to be an alkaline protease. This study reveals that the protease secretion by P. aeruginosa could be monitored effectively in a biological reaction calorimeter. Metabolic heat generated is correlated to protease secretion (non-growth process) for the first time in this study. The heat yields due to biomass growth, substrate uptake and oxygen uptake could help to understand the metabolic process in realistic manner and the results would be useful for bioreactor design and scale up.