Microbal Production Of 1, 3-propanediol By A High Moler Yield Microorignism K. Pneumoniae XJPD-Li

One of the most important ambitious was to obtained higher production in the biosynthesis of 1,3-propanediol. Klebsiella pneumoniae XJPD-Li stored in our Laboratory, could biosynthesize 1,3-PD with a higher molar yield and faster fermentation rate under higher cultivation temperature than other strains reported, isolated from Xinjiang province, China. The fermentation characteristics, domestication, fed-batch technics and kinetic analysis of K. pneumoniae XJPD-Li had been researched. The results were as follows:1. The fermentation characteristics indicated that the optimal temperature and pH were determined as 40℃and 8.0; the optimized nitrogen source was 6.0g·L-1 of (NH4)2SO4, and the concentration of glycerol was 20-30g/L, respectively. Batch fermentation in 5L bioreactor was performed, which displayed that 20 g·L-1 of glycerol was consumed quickly in 8h with the 1, 3-PD production of 12.2 g·L-1 and the molar yield of 1,3-PD to glycerol was 0.75. Fed-batch fermentation indicated a molar yield of 0.59 and the production of 1,3-PD reached 32.01 g·L-1 after 66h.There was a good relationship between the growth of the microorganism and the production of 1,3-PD. The 1,3-PD were mainly produced by K. pneumoniae XJPD-Li in the logarithm phase and the former stable phase.2. The concentration of glycerol showed effect on the fermentation feature of K. pneumoniaeXJPD-Li. Domesticated under the grads concentration of glycerol, the strain could use up the 40 g/L of glycerol while the control remained 21.87 g/L of glycerol in 48h. The biomass (OD650) and the production of 1,3-propanediol were 48% and 159% higher than the original microorganism. In the fed-batch fermentation, the concentration of 1,3-propanediol was increased to 53.13g/L, 77% higher than that of the original. The parameter YP/X, showed the capability of 1,3-PD production, was doubled than that of the original. There was no retrogression in the generation study.3. The strategies of feeding glycerol effected the production of 1,3-PD obviously. Glycerol added with alkali was feasible simplify and conveniently. K. pneumoniae XJPD-Li under different aeration strategies was investigated. A final concentration of 1,3-PD 65.26 g/l and a yield of 1,3-PD 0.56 mol/mol to glycerol were obtained in the fermentation with aerated 0.4vvm air,, where a good productivity of 3.16 g/l·h was achieved in the first 12 h. The biomass and the yield of 1,3-PD were much higher by adding glucose and sucrose in fermentation than that of the control. The analysis of metabolic pathways indicated that the lactate pathway of K. pneumoniae XJPD-Li must be weakened in further research. 4. A kinetic model was proposed based on the Logstic and Luedeking-Piret equations of cell growth, product formation and glycerol consumption. With the evaluation of model parameters, the model could provide reasonable description for the batch fermentation process of K. pneumoniae XJPD-Li. The mechanism analysis of product formation indicated that the 1,3-PD production of K. pneumoniae XJPD-Li was a growth depended mechanism.The investigation of K. pneumoniae XJPD-Li provides the guidance for the biosynthesis of 1,3-propanediol, accelerating the industrial process of 1,3-propanediol. Meanwhile, the research referenced biosynthesis of other alcohols by the microorganisms.