Utilization of 2-alkenoic acids for biosynthesis of medium-chain-length polyhydroxyalkanoates in metabolically engineered Escherichia coli to construct a novel chemical recycling system

This study describes the biosynthesis and thermal degradation of medium-chain-length polyhydroxyalkanoate (PHA), focusing on 2-alkenoic acids as a recyclable carbon source. Using metabolically engineered Escherichia coli, PHA consisting of 3-hydroxydecanoate (3HD) was synthesized from 2-decenoic acid. Solvent cast film of poly(3HD) [P(3HD)] was transparent and showed thermal property similar to that of polycaprolactone. In addition, the use of various 2-alkenoic acids (C6-C12) resulted in production of PHAs with over 95 mol% of the corresponding single monomer units. The pyrolysis product of P(3HD) was dominantly 2-decenoic acid used for the P(3HD) biosynthesis. This demonstrates the feasibility of PHA recycling via 2-alkenoic acids, which act as pyrolysis products and raw materials for PHA biosynthesis.