Kinectic Models of Exopolysaccharide Production by Haemophilus Influenzae Type B

Abstract

Haemophilus influenzae type b (Hib) is a pathogenic bacterium responsible for meningitis in infants and elderly. The polysaccharide present in the extracellular layer of the bacterium is an efficient antigen for vaccination when conjugated to a carrier protein. Immunization against Hib is encouraged to be extended in the developing countries, which sets a high demand on the production of the polysaccharide. The fermentation of Hib is unable to achieve high cell densities, probably due to accumulation of toxic compounds in the broth, decreasing greatly the polysaccharide production yields. In this work, a set of mathematical models were fitted to the experimental data of Hib growth in order to evaluate the kinetics of production of biomass, polysaccharide and acids as byproducts. The best model was chosen by model comparison and allowed us to conclude that polysaccharide formation is exclusively non-associated to growth but inhibited by acid, while acid formation follows a mixed associated and non-associated pattern. These results suggest the model 5.D as mathematical model to predict the fermentation kinetics process of H. influenzae.