A nonlinear dynamic model for diauxic growth of Streptococcus pneumoniae on glucose and cellobiose

In this paper a nonlinear dynamic model has been developed and evaluated experimentally for diauxic growth of Streptococcus pneumoniae on mixed substrates of glucose and beta-glucoside cellobiose. Model parameters are estimated on the basis of real data provided by a set of experiments designed and performed in a microbiology lab. In addition, model sensitivity analysis to parameter variations has been performed with the aim of understanding the biological meaning of parameters. This analysis allowed for reducing the number of significant parameters involved in the model. The resulting model accurately predicts the diauxic behaviour for different initial conditions of cellobiose, with constant glucose initial conditions. The obtained results show that the cellobiose plays the role of inhibitor on bacterial growth. This phenomenon, better appreciated in experimental setups with high cellobiose concentrations, also indicates a possible catabolite repression of cellobiose on glucose at low concentrations. © 2011 IFAC.