Optimization of Conditions for High Production of 3-HPA through Mathematical Modelling of Series Reactions by Resting Lactobacillus reuteri

G. Chen, J. Zhao, Y. Q. Xiao, H. W. Chen and B. S. Fang

Abstract
Glycerol can be converted to 3-HPA and 1,3-propanediol by resting Lactobacillus reuteri. The main catalytic pathway of glycerol is dehydration and reduction. In this study, a novel mathematical model was set up to describe the series reactions of glycerol transformation by L. reuteri. In the model, the cell deactivation rate was proposed by a first order equation with different constants for step one and step two of series reactions. The biotransformation process was satisfactorily simulated by the kinetic model proposed. By comparison of cell deactivation and transformation rate constants under different conditions, the optimal conditions for 3-HPA production by resting cell were obtained. The results showed that the 3-HPA/glycerol yield was highest when the biotransformation was done at glycerol concentration of 200 mmol L–1, pH 6.2 and at 37 °C by resting cell with a concentration of 25.3 g L–1. Under the optimal transformation condition for resting cell of L. reuteri, the inactivation rate constants of cell (k1, k'1) and conversion rate constants (k2, k3) in step one and step two are 0.72 ± 0.04 h–1, 12.54 ± 0.63 h–1, 0.073 ± 0.002 L g–1 h–1, 0.11 ± 0.01 L g–1 h–1, respectively.

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Keywords
Reuterin, Lactobacillus reuteri, kinetics, mathematical model