Study On Production Of 1,3-PDO By High-intensity Fermentation Of Klebsiella Pneumoniae

1,3-Propanediol?referred to as 1,3-PDO?is an important chemical raw material.At present,1,3-propanediol is used to be a monomer for the synthesis of polymer materials such as polytrimethylene terephthalate?PTT?.The production methods of 1,3-PDO include chemical synthesis and biosynthesis.Due to the gradual shortage of some petrochemical resources,the production of 1,3-PDO by biological method has become a research hotspot.In this paper,Based on Klebsiella pueumouia 2-1,which can metabolize glycerol to produce 1,3-PDO,the research work was carried out from the aspects of production process and metabolic pathway transformation.1)The fermentation process of immobilized Klebsiella pueumouia 2-1 cells to produce 1,3-propanediol was optimized.Through single factor analysis and comparison,it was determined that polyvinyl alcohol-cellulose was used as a composite carrier material for immobilized cells.The research results showed that the immobilized particles added with cellulose had a greater improvement in mechanical strength and fermentation strength,and we further clarified the optimal conditions for the immobilization of polyvinyl alcohol-cellulose.The concentration of the polyvinyl alcohol solution was 10%?w/v?,the amount of regenerated cellulose solution was 5%?w/v?,and the secondary cross-linking time was 10h.Compared with the free cells,the first batch of 100m L triangular flask anaerobic fermentation increased the final output of 1,3-PDO by 13.3%.Moreover,when the immobilized cells were continuously fermented,the immobilized cells undergo a slight swelling deformation,and the fermentation intensity was not significantly reduced,so it had the potential to produce1,3-PDO with higher intensity fermentation.2)The continuous fermentation process of immobilized Klebsiella pueumouia 2-1cells in 5L fermentor was studied,a total of 6 batches,a fermentation period of 24h,and initial glycerol concentrations of 30g/L,40g/L,and 50g/L.At the initial glycerol concentration of 50g/L,the second batch of fermentation had the best effect.The fermentation intensity of 1,3-PDO was.After 6 batches of continuous fermentation,the fermentation intensity and the performance of the immobilized particles did not decrease significantly,proving the feasibility of the immobilized particles to produce 1,3-PDO with high intensity continuous fermentation in the fermentation tank.3)In the Klebsiella pueumouia 2-1 phosphotransferase system,the gene crr(soluble glucose-specific transport enzyme EIIA^Glc)was knocked out by?Red recombination technology to eliminate the ability of the strain to mediate carbon catabolism inhibition?CCR?.The results of anaerobic fermentation showed that in the presence of glucose and glycerol,the ability to transport and use glucose was reduced in the Klebsiella pueumouia 2-1?crr.However,compared with the original strain,the yield of 1,3-PDO was increased by 20%and the glycerol conversion rate was also increased by 30%.It is showed that the Klebsiella pueumouia 2-1?crr has the potential to use co-substrate for fermentation.