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Y. K. Jung¹, J.-I. Choi¹, and S. Y. Lee^1,2,*

 ¹ Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical & Biomolecular Engineering, and BioProcess Engineering Research Center

² Department of BioSystems and Bioinformatics Research Center, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Republic of Korea, 3 Korea Research Institute of Bioscience and Biotechnology, 52 Yeoeun-dong, Yuseong-gu, Daejeon, 305-333, Republic of Korea

Keywords: PHB, molecular weight, recombinant E. coli, fed-batch culture

The ultra-high-molecular weight poly([R]-3-hydroxybutyrate) (PHB), having a molecular weight greater than 2 million Da, has recently been found to possess improved mechanical properties compared with the normal molecular weight PHB, which has a molecular weight of less than 1 million Da [1, 2]. However, applications for this PHB have been hampered due to the difficulty of its production. Reported here, is the development of a new metabolically engineered Escherichia coli strain and its fermentation for high level production of ultra-high-molecular weight PHB. Recombinant E. coli strains, harboring plasmids of different copy numbers containing the Alcaligenes latus PHB biosynthesis genes, were cultured and the molecular weights of the accumulated PHB were compared. When the recombinant E. coli XL1-Blue, harboring a medium-copy-number pJC2 containing the A. latus PHB biosynthesis genes, was cultivated by fed-batch culture at pH 6.0, ultra-high-molecular weight PHB could be produced at up to 89.8 g/L with a productivity of 2.07 g PHB/L-h. The molecular weight of PHB obtained under these conditions was as high as 22 MDa, exceeding by an order of magnitude the molecular weight of PHB typically produced in Ralstonia eutropha or recombinant E. coli.

This work was supported by a Korean Systems Biology Research Grant (M10309020000-03B5002-00000) of the Ministry of Science and Technology and by the BK21 project.

[1]     Kusaka S., T. et al., 1997. Appl. Microbiol. Biotechnol. 47, 140-143

[2]     Kusaka S., T. et al., 1998. J Macromol. Sci Pure Appl. Chem. A35, 319-335.

        論文來源：International Symposium on Biological Polyesters ,Auguest 22-27, 2004