Macroscopic modelling of baker's yeast production in fed-batch cultures and its link with trehalose production

• A macroscopic model for fed-batch baker's yeast growth is presented.
• The model includes the influence of nitrogen on carbon source uptake.
• The proposed model is validated with experimental data.
• An extension of this model establishing the link with trehalose production is presented.
• All the numerical results give satisfactory predictions.

A macroscopic model describing the influence of nitrogen on a fed-batch baker's yeast production process is proposed. First, on the basis of a set of biological reactions, inspired by the model of Sonnleitner and Käppeli (1986), a model in which the nitrogen and glucose consumption are coordinated is proposed. Second, an attempt of estimating trehalose concentration in yeast cells through an extension of this model is presented. The model parameters are obtained via a non-linear least squares identification. It is validated with experimental data and successfully predicts the dynamics of growth, substrate consumption (nitrogen and carbon sources) and metabolite production (ethanol and trehalose). This model allows, on the one hand, quantitatively describing the link between nitrogen and glucose consumption in yeast cultures and, on the other hand, will be valuable for the determination of culture conditions aiming at maximizing yeast productivity while guaranteeing the accumulation of a required amount of trehalose.