The Inference Of The Inhibition Of 3-Hydroxypropionaldehyde To The Two Enzymes Based On Robustness Analysis

The continuous fermentation of bio-dissimilation of glycerol to 1,3-propane-diol (1,3-PD) by Klebsiella pneumoniae(K.pneumoniae) are investigated in this paper. based on the different cases on the inhibitions of 3-hydroxypropionaldehyde (3-HPA) to the effect activities of two key enzymes (glycerol dehydratase (GDHt)and 1,3-propanediol oxydore-ductase (PDOR)), a nonlinear hybrid dynamical system is proposed on the hypothesis that the glycerol and 1,3-PD pass the cell membrane by both passive diffusion and active transport and that there is no inhibition of 3-HPA to the specific growth rate of cells. And the fundamental properties of the system are investigated. To infer the most rea-sonable case, a quantitative definition of biological robustness is presented. Taking the presented biological robustness as performance index, a system identification model is established. Finally, we obtain the most reasonable system to describe the inhibition of 3-HPA to the two key enzymes and compute the range of inhibition of 3-HPA to the two enzymes by numerical computation.This work was supported by National Natural Sci-ence Foundation "Optimization theory and algorithm of nonsmooth dynamic system in a class of complex networks" (No.10871033) and the National High Technology Research and Development Program(863 Program) "Biodiesel and 1,3-Propanediol Integrated Pro-duction"(No.2007AA02Z208). The main results obtained in this dissertation may be summarized as follows:1. During the continuous culture of glycerol bioconversion to 1.3-PD, based on the cases whether the inhibitions of 3-HPA to the effect activities of two key enzymes ( GDHt and PDOR), we propose a nonlinear hybrid dynamical system on the hypothesis that the glycerol and 1,3-PD pass the cell membrane by both passive diffusion and active transport and that there is no inhibition of 3-HPA to the specific growth rate of cells. And the fundamental properties of the system are investigated:the existence and uniqueness of the solution to the system and the continuous dependent with respect to parameters.2. Because of the lack of intracellular information, we propose a quantitative defini-tion of biological robustness. taking the average relative error of extracellular substance concentrations and the biological robustness as performance index, we establish an iden-tification model containing discrete and continuous parameters, which is subject to some conditions including the proposed nonlinear hybrid dynamical systems and the approxi- matelv steady state of the dynamical system. Subsequently, we prove the identifiability of the model. Finally, we obtain the range of inhibition of 3-HPA to the two enzymes by numerical computation.