The study of 1,3-propanediol production byengineering glycerol metabolic related genes in Klebsiella pneumoniae

• Main Authors: Ta-Chung Chou, 周大中
• Other Authors: Po-Chi Soo
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/54251690711871431585

碩士 === 元智大學 === 生物科技與工程研究所 === 97 === 1,3-propanediol (1,3-PD) is an important organic compound in chemical industry,and this compound could potentially be used for many synthesis reactions, such as a monomer to produce polyesters, polyethers and polyurethanes. The polyesters which were synthesized by 1,3-PD has unique and outstanding performance; moreover, 1,3-PD may enable the polyesters easy to have the characteristic of natural circulation and biodegradation . In recent study, there are many different microorganisms that produce 1,3-propanediol, such as Klebsiella pneumoniae, Klebsiella oxytoca, Clostridium butyricum, Citrobacter freundii, Enterobacter agglomerans and Lactobacillus brevis. In this study, in order to facilitate the conversion of glycerol to 1,3-PD in K. pneumoniae, we employed the homologous recombination to knock out two important genes, dhaD and dhaK, in glycerol oxidation pathway to eliminate side products during glycerol metabolism. The result indicated that although the side products in glycerol oxidation pathway such as lactate, 2,3-butanediol and ethanol were successfully eliminated in mutant strain TC100, the productivity of 1,3-propanediol of wild type (WT) and TC100 were 5.59(g/L) and 1.91(g/L), respectively. To further promote the 1,3-PD productivity, we directly overexpressed the genes dhaB and dhaT, involved in 1,3-PD formation, by transforming expression vector into TC100. We verified that the enzyme activities of DhaB or DhaT were higher in the recombinant strains TC101 (TC100/pBAD-dhaB) and TC105 (TC100/pBAD-dhaT) compared with TC100. Using high performance liquid chromatography, the 1,3-PD productivity of TCKP01(WT/pBAD-dhaB) and TCKP05(WT/pBAD-dhaT) were both 1.01% higher than wild type strain respectively. Onther the other hand, the 1,3-PD productivity of TC101 and TC105 were 20.4% and 56.6% higher than TC100. In this study, we corroborated that deletion of dhaD and dhaK led to reduce side products and overexpression of dhaB and dhaT facilitated the 1,3-PD productivity in K. pneumoniae. The recombinant strain(s) would be a great industrial application in the production of 1,3-PD.