Modeling the Influence of pH, Temperature and Culture Medium Composition on the Kinetics of Growth and Cysteine Proteinase Production by Micrococcus sp. INIA 528 in Batch Culture

Abstract

Kinetics of biomass and cysteine proteinase formation during growth of Micrococcussp. INIA 528 in batch cultivation were studied. Modeling of cultivation data was carried out using an unstructured model. The logistic equation was found to be adequate to describe microbial growth. Production of cysteine proteinase was described by means of an equation including biomass and substrate concentrations. An overall model based on an equation of substrate consumption dependent on biomass formation and proteinase production was postulated. The kinetic parameters (specific growth rate, maximum biomass, proteinase production rate and proteinase formation yield) were obtained taking into account the influence of pH (6.0–8.0), temperature (28–41 ºC) and the addition of different supplements to the basal culture medium [yeast extract, MgSO 4,glucose, K2HPO4 and (NH4)2SO4]. Kinetic parameters were calculated by fitting experimental data by a nonlinear technique using the algorithm of Marquardt coupled to a fourth-order Runge-Kutta subroutine.