Unstructured kinetic model for sophorolipid production by Candida bombicola

Abstract

A kinetic model for sophorolipid production by Candida bombicola is proposed. The unstructured nonsegregated kinetic model takes into account three responses: biomass, sugar, and sophorolipid. In the kinetic model, the nitrogen—from yeast extract—is assumed to be the limiting nutrient of the yeast growth, the sugar—glucose—is assumed to be used in both growth and sophorolipid production, and oil is supposed to be spent in product formation and maintenance of biomass is attributed to glycerol eased by the catabolism of the oil. The parameters of the kinetic model are calculated by fitting model to experimental data. These data have been obtained in experiments in which a batch stirred and an aerated tank bioreactor have been used. Fitting has been carried out according to a nonlinear regression algorithm, coupled with a Runge–Kutta method for the interpretation of integral data (evolution of system composition with time). The proposed kinetic model is able to explain both our experimental data and data given by other authors in previous works in literature in which nutrient and product concentrations evolution are given.