Structural identifiability of the yield coefficients in bioprocess models when the reaction rates are unknown

The identification problem of bioprocesses in a stirred tank reactor essentially concerns the determination of the yield coefficients and the reaction rates involved in a general state-space model. This paper deals with the analysis of structural identifiability of the yield coefficients issuing from a two-step identification procedure. In fact, the identification of the yield coefficients can be completely decoupled from that of the reaction rates by means of an appropriate transformation of the dynamical model. It is shown that the identifiability properties of these coefficients can be drawn from the structure of the underlying reaction network. Necessary and sufficient identifiability conditions are given in the form of some simple algebraic tests.