Complementary Bacterial Functions Enhance Mineralization of Aromatic Aliphatic Copolyesters within a Marine Microbial...

Plastics are a major environmental concern due to their persistence in natural systems. Biodegradable plastics can mitigate this impact by reducing their residence time in the environment. To constrain the environmental lifetime of these materials, understanding the fundamental principles dictating their biodegradation is crucial. The work presented here probes this complexity by using a 30-member bacterial community enriched from the marine ecosystem to investigate how bacterial consortia mineralize polybutylene sebacate-co-terephthalate (PBSeT), a biodegradable aromatic aliphatic copolyester. Carbon dioxide quantification and isotopic tracing provided evidence of polymer mineralization, while monoculture phenotyping demonstrated no one bacterium could consume all polymer components. Further, coculture incubations revealed complementary functions between community members enhanced mineralization. To explain this enhanced mineralization, dissolved organic carbon and chemical product tracking were performed. Notably, depolymerization of the bulk polymer was dictated by a bacterium unable to consume all polymer components (Pseudomonas pachastrellae), requiring complementary bacteria to achieve enhanced mineralization (Pseudooceanicola nitratireducens or Peribacillus frigoritolerans). This yielded direct experimental evidence of the complementary bacterial transformations that may control polymer mineralization in the environment.