[Construction of recombinant Escherichia coli strains producing poly (4-hydroxybutyric acid) homopolyester from glucose].

The aim of this study is to construct recombinant Escherichia coli strains capable of producing poly(4-hydroxybutyric acid) homopolyester from glucose as sole carbon source. A glutamate: succinate semialdehyde transaminase gene from Escherichia coli, a glutamate decarboxylase gene from E. coli, and a 4-hydroxybutyrate dehydrogenase gene from Ralstonia eutropha were cloned by PCR and assembled onto the plasmid pKSSE5.3 which haboured the PHA synthase gene from Ralstonia eutropha and 4-hydroxybutyrate: CoA transferase from Clostridium kluyveri. The resulting plasmids were transformed into E. coli and the pathway for biosynthesis of poly(4-hydroxybutyric acid) from glucose via alpha-ketoglutarate, an intermediate in TCA cycle was established in recombinant E. coli strains. Recombinant strains synthesized the homopolyester P(4HB), when cells were cultivated in Luria-Bertani broth with glucose as carbon source. P(4HB) accumulation was enhanced up to 30% of cell dry weight, when cells were cultivated in mineral salts M9 medium plus glucose as sole carbon source with addition of yeast extract, tryptone, casein hydrolate into medium respectively.