Biosynthesis of Novel Aromatic Copolyesters from Insoluble 11-Phenoxyundecanoic Acid by Pseudomonas putida BM01

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Abstract
Two types of novel aromatic copolyesters were synthesized from 11-phenoxyundecanoic acid (11-POU) as the sole carbon source and the cosubstrates 11-POU and octanoate, respectively, by isolated Pseudomonas putida BM01 that is known to accumulate high concentrations of medium-chain-length polyesters. Insoluble 11-POU was recrystallized in situ in buffer by alkaline treatment and pH adjustment, followed by autoclaving. The resulting microcrystals, whose structure was different from that of the commercially available crystalline powder, suspended in media were rapidly consumed by the bacterium. Synthesized polymers were characterized by gas chromatography, nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. The aromatic copolyesters synthesized from 11-POU were composed of two monomer units consisting of 3-hydroxy-5-phenoxyvalerate (5POHV) as the major component (72 to 85 mol%) and 3-hydroxy-7-phenoxyheptanoate (7POHH) as the minor component (15 to 28 mol%). The aromatic copolyesters showed a crystalline melting transition at 70(deg)C. When the bacterium was grown on the cosubstrates 11-POU and octanoate, the bacterium synthesized the copolyesters composed of aromatic and aliphatic monomers poly(5POHV-co-7POHH-co-3-hydroxy-9-phenoxynonanoate-co-3-hydroxyalkanoates) . The addition of octanoate in the feed shifted the major monomer unit in the polymer from 5POHV to 7POHH. A further-fragmented metabolite, 3-phenoxypropionate, whose concentration reached a steady state at the time of greatest polyester accumulation, was detected in the medium. The metabolic pathway of 11-POU is suggested.