Formation of novel poly(hydroxyalkanoates) from long-chain fatty acids

Abstract

Poly(hydroxyalkanoates) (PHAs) were isolated from Pseudomonas aeruginosa 44T1 cultivated on euphorbia oil and castor oil. With the aid of 2-D proton NMR spectra and proton-detected multiple bond coherence NMR spectra the structures of the PHAs were determined. In addition to the usual PHA constituents (C6-C14 3-hydroxy fatty acids), PHAs formed from euphorbia oil contained delta 8,9-epoxy-3-hydroxy-5c-tetradecenoate, and probably delta 6,7-epoxy-3-hydroxydodecanoate and delta 4,5-epoxy-3-hydroxydecanoate. These novel constituents account for approximately 15% of the total amount of monomers and are clearly generated via beta-oxidation of vernolic acid (delta 12,13-epoxy-9c-octadecenoic acid), the main component of euphorbia oil. In PHAs formed from castor oil, 7% of the monomers found were derived from ricinoleic acid (12-hydroxy-9c-octadecenoic acid). The presence of 3,8-dihydroxy-5c-tetradecenoate was clearly demonstrated. Furthermore, NMR analysis strongly suggested the presence of 3,6-dihydroxydodecanoate, 6-hydroxy-3c-dodecenoate, and 4-hydroxydecanoate.