MODELING OF E. COLI GROWTH, GLUCOSE CONSUMPTION, AND RECOMBINANT COLLAGEN-LIKE PROTEIN FORMATION KINETICS

Abstract

Mathematical modeling of the kinetics of fermentation processes is crucial to understand complex microorganism behavior and identify problems. To investigate growth kinetics, as well as glucose utilization and recombinant collagen-like protein formation kinetics, E. coli BL21 (DE3) harboring a collagen-like protein from Rhodopseduomonas palustris (RPCLP) was cultivated in M9-casamino acids medium containing glucose (10 g/L). OD600 and a glucose assay kit were used to monitor the biomass concentration and glucose depletion, respectively.  The RPCLP concentration was measured via a fluorometric assay. Results show that the maximum biomass achieved was 8.25 g/L, whereas the maximum RPCLP yield was 2 mg/L. Growth data was then fitted into unstructured models- Monod model and logistic model. The Luedeking-Piret model was used for the substrate utilization and product formation data. Kinetic parameters were determined by nonlinear regression and ANOVA analyses were done to determine the significance of each fit. While the growth data fitted both the Monod and the logistic model well, with significant coefficients of determination (R² values 0.96 and 0.99, respectively), the Luedeking-Piret models did not represent the substrate utilization and product formation well (correlation coefficient = 0.7). The study suggests that the production is mixed-growth associated and modification of the model is required.