High-load terephthalic acid degradation and diverse bioproduct formation by novel Rhodococcus strains

Terephthalic acid (TPA) from poly(ethylene terephthalate) (PET) depolymerization is a promising substrate for microbial upcycling, yet complete degradation at high concentrations has not been reported above 120 mM. Here, we report seven Rhodococcus strains isolated from compost enrichment cultures using TPA as the sole carbon source. Three isolates completely consumed 240 mM TPA in minimal medium under high osmolarity conditions, surpassing the previously reported threshold. Strain TA18 produced β-linked exopolysaccharides and a polyhydroxyalkanoate composed mainly of 3-hydroxyvalerate from TPA as the sole carbon source, neither of which has been previously described from this substrate in Rhodococcus, alongside C16 and C18 fatty acids. These strains expand the set of robust TPA-assimilating bacteria available for PET upcycling and provide a foundation for developing routes that convert plastic waste streams into multiple microbial products.