Complete Utilization of Poly(butylene Adipate-co-terephthalate) Monomers and Production of Polyhydroxybutyrate by a Levulinic Acid-Mediated Microbial Consortium of Pseudomonas putida and Cupriavidus necator.
Poly(butylene adipate-co-terephthalate) (PBAT) is a biodegradable plastic with enhanced mechanical properties, which can serve as a substitute for conventional plastics. However, the monomers released during its biodegradation, such as adipic acid (AA), 1,4-butanediol (1,4-BDO), and terephthalic acid (TPA), accumulate into the environment or are not simply consumed through central metabolism, limiting their resource value. Therefore, designing a single strain that can efficiently consume all monomers is challenging. Here, a consortium comprising Pseudomonas putida KT2440 harboring tpaK, tphA, and tphB which metabolizes 1,4-BDO and TPA and Cupriavidus necator H16, which converts AA into polyhydroxybutyate (PHB) via β-oxidation was constructed to convert all PBAT-derived monomers into PHB. To enhance polyhydroxyalkanoate production, a levulinic acid (LA)-producing strain GP101 was added to the consortium, resulting in 0.75 g/L PHB and 0.20 g/L 4-hydroxybutyrate (4HB) production and representing a 6.25-fold increase in PHB production compared to that by the consortium containing P. putida KT2440 that could not produce LA. Optimizing the strain ratio of P. putida KT2440 GP101 to C. necator H16 to 2:1 resulted in maximum production of 0.98 g/L PHB and 0.52 g/L 4HB, and all PBAT-derived monomers were completely disappeared within 30 h. This is the first study to demonstrate complete utilization of PBAT monomers and valorization into PHB by an LA-mediated microbial consortium. This approach reveals controllable and reproducible consortia beyond the complex design of a single strain and simple treatment of each monomer, demonstrating the feasibility of converting PBAT-derived monomers into value-added products.