Abstract

Pseudomonas sp belonging to group I of rRNA homology are capable to synthesize medium-chain-length polyhydroxyalkanoates (PHAmcl), biodegradable polyesters with elastomeric and biocompatible characteristics, which can be produced from renewable resources and therefore show great industrial interest. Mechanical and physical properties of these polymers depend on its monomeric composition. PHAmcl can be synthesized from several carbon sources like, carbohydrates, alcohols, fatty acids, alkanes, etc. When aliphatic substrates are used, greater yields are expected and functional groups can be incorporated to polymer allowing its posterior modification. Considering that pure fatty acids are very expensive; animal fats, plant oils and their fatty acids have been explored as raw materials aiming at the production of PHAmcl with compatible cost. In this work, PHAmcl with distinct compositions were produced from eleven different plant oils (pure or mixtures) by Pseudomonas putida and Pseudomonas aeruginosa. These strains produced PHA presenting differences on monomer composition compatible with variability on monomer specificity of their PHA biosynthesis system. In all the PHA synthesized, was observed the presence of unsaturated monomers. A high molar fraction of 3-hydroxy-5-dodecenoate (3HDdΔ5) was detected in the PHA produced from tung oil. A correlation between the molar fractions of 3-hydroxy-6-dodecenoate (3HDdΔ6) detected in PHA and the linoleic acid supplied was observed. Although P. putida showed a higher 3HDdΔ6 yield from linoleic acid when compared to P. aeruginosa, in both species it was greatly lower than the maximum theoretical value. These results contribute to the knowledge about the biosynthesis of PHA with a controlled composition from plant oils allowing in the future establishing the production of these polyesters as tailor-made polymers.