Biosynthesis pathway related production of medium chain length polyhydroxyalkanoates

Pseudomonas flava HBE06 isolated from oil-contaminated soil was found to produce polyesters consisting of medium chain length polyhydroxyalkanoates (mcl PHA). The strain mainly synthesized PHA containing 3-hydroxyoctanoate (C 8 or HO), 3-hydroxynonanoate (C 9 or HN), 3-hydroxydecanoate (C 10 or HD), and 3-hydroxyunidecanoate (C 11 or HUD) as monomers when grown on various substrates. It was found that the monomer ratio (especially C 10 /CS 8 or C 11 /C 9 ) was related to the PHA biosynthesis pathway. When PHA was synthesized via the de novo fatty acid pathway, the molar ratio of C 10 /C 8 was greater than 2. If PHA was synthesized from β-oxidation of fatty acids, C 10 /C 8 was less than 1. Pseudomonas stutzeri 1317 is another mcl PHA synthesizing bacteria whose C 10 /C 8 ratio is also related to the synthesis pathway. When the two synthesis pathways were used together, the C 10 /C 8 ratio could be adjusted according to the ratio of the mixed substrates.