Screening Of Strains Able To Production Of 1,3-Propylenediol From High Concentration Of Glycerol And Study On Fermentation Kinetics

1,3-propanediol(1.3-PD) is acknowledged as one of six new petrochemical products currently in the world.Its main function is an important monomer to synthesize a new type of polyester,polyether,polyurethane.1,3-Propanediol is produced by two ways,chemical synthesis and microbial conversion.It has advantages for high-converting enzyme and expression efficiency. Producing 1,3-propanediol by microbial fermentation have many obvious advantages and become the focuses of research.This article made the following findings:1, Screening to tolerate high concentrations of glycerol 1,3-propanediol producing strainScreening of high concentrations of glycerol tolerant strains improve from a final glycerol concentration of 10% to 30% gradually, out of the low strain tolerance of glycerol, from the outset a high tolerance to strain glycerine. Furthermore inquiries may utilize glycerol microbial synthesis product, find a microorganism from glycerol and three found a strain capable of producing 1,3-propanediol(labeled D1), and thus its physiological and biochemical experiments and 16 Sr RNA homology phylogenetic analysis to determine the status of this strain came to the conclusion that it is Klebsiella conclusions.2, optimized production strains medium composition and main technical parametersPreliminary experiments using single factor optimization Klebsiella growth medium components and fermentation medium conditions were investigated in different components of the starter culture bacteria culture and fermentation of the product, and the use of response surface experimental design optimization the medium composition. Optimization of growth medium were: KH2PO4 1.49g/L,K2HPO4 3.4 g/L,(NH4)2SO4 3 g/L,Ca Cl20.02 g/L,Fe SO4 1.3 g/L, yeast extract, 1 g/ L, glycerol 50.3 g / L, for the optimization of fermentation medium: KH2PO4 1.5g/L,K2HPO43.4 g/L,(NH4)2SO4 3 g/L,Ca Cl20.047 g/L,Fe SO4 0.01 g/L, yeast extract1.2 g / L, glycerol 224.22g/L. Fermentation optimized than the previous optimization1,3-propanediol production increased by 58.92%. It was also the use of orthogonal experiment to optimize the seed fermentation process parameters were investigated the effects of p H, temperature and shaking speed and other parameters of the fermentation conditions. The optimum conditions for optimization of parameters:p H7.0, shaking bottled liquid volume 40 ml / 250 ml flask, fermentation temperature of37 ℃.3, The establishment of a 1,3-propanediol fermentation kineticsBy optimizing the fermentation process to detect glycerol consumption rate, the rate of cell growth rate and generate product. Established fermentation kinetics model to determine the fermentation kinetics model of the species. By fitting the kinetic model indicates that the strain fermentation of 1,3-propanediol is a typical type II cell growth and product formation portion fermentation phase-coupled mode in which cell growth kinetics: Cell specific growth rate and product ratio is the relationship between the rate of synthesis:4, Discussing the metabolic pathways of bacteria Synthesis of 1,3-propanediolExperiments investigated in 1,3-propanediol during fermentation to produce1,3-propanediol, while the generation of other organic acids, according to the analysis of the metabolites of the metabolic pathways to further clarify the synthesis of1,3-propanediol strain of bacteria is determined species in vivo metabolic flux distribution for the next step to achieve optimal metabolic flux network physiological bacterial metabolic pathways by metabolic engineering perspective provided.For screening to a height tolerance glycerol strains in preliminary experiments to ensure that the strain at high concentrations of glycerol grown out of the strain must be screened in order to have a high tolerance. Then subjected to experiments to explore the optimum growth and fermentation conditions, we found Qi growth and fermentation conditions are far apart, so a two-step fermentation method to explore the dynamics of fermentation byproducts, and laid a foundation for industrial production.3,Experiments established fermentation kinetics model. Kinetic model fitting show that the growth of the strain was II type and the product was partially coupled.