Biosynthesis of poly(3-hydroxy-alkanoates) in Pseudomonas aeruginosa AO-232 from 13C-labelled acetate and propionate.

Pseudomonas aeruginosa AO-232 produced poly(3-hydroxyalkanoates) (P(3HA)) containing monomer units of even carbon numbers C6, C8, C10 and C12, when sodium acetate was fed as the sole carbon source. In contrast, the P(3HA) produced from sodium propionate was composed of seven different 3HA units ranging from C6 to C12. The pathways of P(3HA) synthesis were investigated by using 13C-labelled acetate and propionate as the carbon sources. The 13C-labelled carbonyl carbon of [1-13C] acetate was selectively incorporated into the odd-numbered carbon atoms of 3HA units, while the methyl carbon of [2-13C] acetate was introduced into the even-numbered carbon atoms of 3HA units. The 13C-labelled carbonyl carbon of [1-13C] propionate was selectively incorporated into the third carbon atoms from methyl carbons in the 3HA units of C7, C9 and C11. The synthesis of P(3HA) from acetate or propionate was related to de novo fatty acid biosynthesis.