Plastic-Degrading Microbial Consortia from a Wastewater Treatment Plant.

Plastic waste pollution has become a global crisis, with millions of tons of plastic expected to accumulate in landfills and in natural environments, posing a serious threat to wildlife and human health. As current recycling methods remain inefficient, there is an urgent need for innovative enzymatic solutions to break down plastics and enable a circular economy approach. In this study, we explore the plastic-degrading potential of microorganisms enriched from activated sludge (AS) sourced from a municipal wastewater treatment plant (WWTP)-a known microplastic-contaminated industrial niche. Five microbial consortia (i.e., microbiomes) were enriched under selective pressure using low-carbon conditions and high concentrations of polyester polymers, including post-consumer PET, post-consumer PLA, and virgin PLA. Enrichment was performed for 100 days at 37 °C and 50 °C, followed by microbiomes isolation and metagenomic analysis to identify plastic-active bacteria and their enzymes. The results revealed that PLA polymers, but not post-consumer PET, were effectively degraded by the microbiomes, as confirmed by nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC), showing significant molecular weight reduction compared to the abiotic controls. Microbial community analysis highlighted a distinct enrichment profile driven by the polymer composition and the temperature. At 50 °C, the