1. Enhancement of glycerol utilization ability of Ralstonia eutropha H16 for production of polyhydroxyalkanoates.
- Author
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Fukui, Toshiaki, Mukoyama, Masaharu, Orita, Izumi, and Nakamura, Satoshi
- Subjects
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GLYCERIN , *RALSTONIA eutropha , *POLYHYDROXYALKANOATES synthesis , *GENE expression profiling , *ESCHERICHIA coli , *BIODEGRADABLE plastics - Abstract
Ralstonia eutropha H16 is a well-studied bacterium with respect to biosynthesis of polyhydroxyalkanoates (PHAs), which has attracted attentions as biodegradable bio-based plastics. However, this strain shows quite poor growth on glycerol of which bulk supply has been increasing as a major by-product of biodiesel industries. This study examined enhancement of glycerol assimilation ability of R. eutropha H16 by introduction of the genes of aquaglyceroporin ( glpF) and glycerol kinase ( glpK) from Escherichia coli. Although introduction of glpFK into the strain H16 using a multi-copy vector was not successful, a recombinant strain possessing glpFK within the chromosome showed much faster growth on glycerol than H16. Further analyses clarified that weak expression of glpK alone allowed to establish efficient glycerol assimilation pathway, indicating that the poor growth of H16 on glycerol was caused by insufficient kination activity to glycerol, as well as this strain had a potential ability for uptake of extracellular glycerol. The engineered strains expressing glpFK or glpK produced large amounts of poly[( R)-3-hydroxybutyrate] [P(3HB)] from glycerol with much higher productivity than H16. Unlike other glycerol-utilizable wild strains of R. eutropha, the H16-derived engineered strains accumulated P(3HB) with no significant decrease in molecular weights on glycerol, and the polydispersity index of the glycerol-based P(3HB) synthesized by the strains expressing glpFK was lower than those by the parent strains. The present study demonstrated possibility of R. eutropha H16-based platform for production of useful compounds from inexpensive glycerol. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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