Parameter Identification And Robust Analysis Of Complex Dynamical Systems In Microbial Continuous Fermentation

The enzyme-catalytic complex dynamical systems of bio-dissimilation of glycerol to 1,3-propanediol by Klebsiella pneumoniae are investigated in this paper.Basing on enzyme-catalytic kinetic model of continuous fermentation,considering the different transport ways of extracellular glycerol on the reductive pathway,the complex dynamical systems including three models are established and the properties of solutions are studied.The study of the new model can not only be helpful for deeply understanding metabolic and genetic regulation of dha regulon of glycerol metabolism,but also provide certain reference for genetic modification of Klebsiella pneumoniae.This work was supported by the tenth 5 years' projects of Science and Technology Administration of China "Microbial Production of 1,3-Propanediol"(No.2001BA708 B01-04) and National High Technology Research and Development Program of China(863 Program)" Biodiesel and 1,3-Propanediol Integrated Production"(No.2007AA02Z208).The main results obtained in this dissertation may be summarized as follows:1.The transport mechanism of glycerol and 1,3-PD across cell membrane on the reductive pathway is analyzed and discussed.Under the assumption that 1,3-PD passes the cell membrane by both passive diffusion and active transport,considering three different transport ways of extracellular glycerol separately which are active transport,passive transport as well as active and passive transport,the enzyme-catalytic complex dynamical systems are developed by Michalis-Menten kinetics.We prove some basic properties of the systems,such as existence and uniqueness of the solution.Moreover,parameter identification models of complex dynamical systems are established and the identifiability of models is proved.The feasible optimization algorithm is constructed to find the optimal parameters for the models in accordance with the experimental data.The numerical simulation show that the relative errors between experimental and computational values of 1,3-PD is 30%or so.According to the actual biological system,the models presented in this paper are fit for formulating the factual fermentation.2.A new analysis method of biological robustness is proposed.As the stability of model depends crucially on the precise numerical values of sensitive kinetic parameters,from the perspective of a change in these parameters,a quantitative performance index of robustness and its optimization algorithm are established,then the robustness of each model in complex dynamical systems is analyzed.According to the value of objective function,we can select a reasonable system to reflect the transport mechanism of glycerol.The numerical results of robustness indicate that performance index of parameter identification is not perfect to be the unique standard to select a reasonable model,so robust analysis for each model is necessary.