Pathway And Parameter Identification Of The Gene Regulation Of Nonlinear Dynamic System

The bioconversion of glycerol to 1,3-propanediol(1,3-PD)by Klebsiella pneumoniae can be characterized by a complex biological engineering.Considering the concentration of nine intracellular substance can't be measured in the experiment and there exists many possible me-tabolic pathway,we establish a 14 dimensional nonlinear hybrid dynamical system with gene-tic regulation to describe the continuous fermentation process.Meanwhile,this dynamical sy-stem takes into account the repression of 3-hydroxyl propylaldehyde to dha regulator of gene expression and the inhibition of the enzymes.The main research results are summarized as follows:1.On the basis model of Yanjie Guo,considering not only the genetic regulation mechanisms,but also the inhibition of 3-HPA,and supposing that glycerol and 1,3-PD transport across cell membrane by active transportation combined with passive diffusion,we propose a 14 dimensio-nal nonlinear hybrid dynamical system with genetic regulation in order to identify the possible pathway and parameters.Some basic properties of the system are discussed.2.We define the relative error of the extracellular concentrations and the biological robustness of system in regard to parameters of intracellular concentrations.Taking the sum of relative error and the biological robustness as a performance index and the nonlinear hybrid dynamical system as the constraint condition,we propose a system identification model and prove the existence of optimal solution of the model.3.The model IP includes both continuous variables and discrete variables,and these two types of variables are completely independent of each other.Because the identification problem IP contains a great amount of numerical calculation,which is very difficult to be solved directly,we decompose the problem IP into two sub-problems and prove that decomposition identifyca-tion problem is equivalent to the identification problem IP.We propose a parallel PSO algori-thm to solve it,analyze the robustness of metabolic subsystems under different pathways,and obtain the optimal pathway and parameters.Finally,we give the simulated resu Its and simulat-ed diagrams about 14 material concentration changing with fermentation time comparing with a set of experimental data.