Biosynthesis of polyester blends by Pseudomonas sp 61-3 from alkanoic acids

Pseudomonas sp. 61-3 accumulated poly(3-hydroxyalkanoates), P(3HA), in nitrogen-free media containing medium- and long-chain alkanoic acids or plant oils. The polyesters of 3HA units of even carbon numbers ranging from C4 to C12 were produced from the alkanoic acids of even carbon numbers, while those produced from the alkanoic acids of odd carbon numbers contained 3-hydroxybutyrate (3HB) and 3HA units of odd carbon numbers of C5 to C11. The strain produced simultaneously P(3HB) homopolymer and a random copolymer of 3HA units of C4 to C12 within cells from the alkanoic acids of even carbon numbers, while a copolymer of 3HB and 3-hydroxyvalerate was formed with a random copolymer of 3HA units from the alkanoic acids of odd carbon numbers. The results suggest that Pseudomonas sp. 61-3 has two types of PHA synthases with different substrate specificities.