Determination of biomass yield for growth of Candida utilis on glucose: Black box and metabolic descriptions

Similar to some complex chemical systems, many reactions are involved in a microbial process. One of the initial tasks for both systems consists of co nsidering the stoichiometric relations among the different chemical reactan ts. In the present work, a methodology to establish the stoichiometric rela tions in microbial processes is shown. The yield of biomass from the C-sour ce can be calculated from these relations by using two types of system desc riptions found in the literature, the black box model and metabolic descrip tion. The former represents microbial growth by means of a chemical reactio n which contains the accumulating compounds. The description is based on el ement, electric charge and Gibbs energy balances. The metabolic model also describes the intracellular biochemical reactions. The model is based on th e specification of a set of reactions which contain all the accumulating an d catalytic species. In the present work, the biomass yield is calculated f or the Candida utilis-glucose system by using both models. Results are comp ared with the measured yield and the available data in the literature, show ing a good agreement.