| 摘要 |
Production of medium chain length poly-3-hydroxyalkanoates (mcl-PHAs) in Escherichia coli is reported for the first time. To produce PHA in E. coli, a PHA polymerase encoding gene (phaC2) of Pseudomonas oleovorans GPo1 was introduced into various E. coli strains and fatty acid oxidation mutants thereof. Of these, E. coli fadA/B, E. coli fadRfadA or E. coli fadRfadB mutants, which are defective in specific steps of the fatty acid beta -oxidation pathway, allowed production of mcl-PHAs from fatty acids ranging from octanoate to octadecanoate. Maximum amounts of about 10% PHA of total cell dry weight (w/w) were found. The predominant monomers found in these PHAs were always the same, independently of the chain length of the supplied fatty acids: 3-hydroxyoctanoate for even chain length fatty acids and a combination of 3-hydroxynonanoate and 3-hydroxyheptanoate for odd chain length fatty acids. Since the monomer composition of the produced polymer was independent of the fatty acid chain length, beta -oxidation occurs in these beta -oxidation mutants. The polymer may be hydrolyzed to yield interesting optically active monomers and their esters. |
