M Feyzdar - Control Engineering Group, Department of Electrical Engineering, Damavand Azad University, Tehran, Iran.
V Babaeipour - Biotechnology Research Center, Malek Ashtar University of Technology, Tehran, Iran۱.
A . R Vali - Control Engineering Group, Department of Electrical Engineering, Damavand Azad University, Tehran, Iran.

Nonlinear dynamical models play an important role in bioprocess engineering, so it is important to deal with the structure identification of these models. This paper explores the structure identification of a biotechnological process based on experimental data. The process considered in this study is fed-batch cultivation of E. coli BL21 (DE3) [pET3a-ifnγ] under maximum attainable specific growth rate in per-induction and constant feeding at post-induction for producing human γ-Interferon protein. Dynamic order of the process model was determined with Lipschit test andGenetic Programming algorithm applied for structure identification of the process. Model complexity was reduced by Orthogonal Least Square method during structure identification procedure with eliminating the superfluous model terms. Validation results show good compatibility with experimental data and residual errors between estimated outputs and experimental data are less than 0.05.

E. coli, Fed-batch, Genetic Programming, Lipschit Test, Orthogonal Least Square