The Research Of Glucose Oxidatin Pathway And Produced Xylonic Acid In Klebsiella Pneumoniae

This paper studies the glucose oxidative pathway in Klebsiella pneumoniae. As a kind of important industrial microorganism, it is generally believed that glucose is transferred into Klebsiella pneumoniae intracelluar pathways in four pathways: 1) glucose is transferred to the intracelluar before oxidized to 2-keto gluconic acid in plasmic space; 2)glucose is oxidized to gluconic acid in the plasmic space, then gluconic acid is transferred into intracelllar; 3) glucose enter the intracellular by ABC transport system directly; 4)glucose enter the intracelluar by PTS transport system directly. Based on previous reserach, this paper explores further work about glucose oxidation in Klebsiella penumoniae. By the methods of genetic recombination, more than 10 single mutants 、double genes mutants and three genes mutants were constructed successfully. Mutants were inoculated to the M9 medium, with 2-keto gluconic, gluconic acid and glucose as the single carbon source. According to the experimental results, we concluded that existed other ways in glucose oxidative pathway.Gene LuxS as the key gene conducts the bacteria growth density, which influences the fermations of Klebsiella penumoniae to produce 2,3-BD and acetoin: the final production is increased significantly in the fermation of 2,3-BD; the fermentation time of acetoin is shorter. On the other hand, the fermation for 1,3-PD do not change significantly.Based in previous research, we had koncked out the gene gad in Klebsiella pneumoniae, which is the key gene represents the activity of gluconate dehydrogenase. It was achieved the goal of glucose acid accumulation by controlling the pH. Through the batch fermentation datas,we can see that the natural strains of Klebsiella pneumoniae and mutant strains kpΔgad can use normal growth metabolism of xylose translated to xylonic acid. At fed bath fermentation, 104.32 g/L xylonic acid was produced at 79 h with the conversion ratio 1:1. K. pneumoniaeΔgad as a xylonic acid production potential strains used in modern industrial production.