Plastic-Degrading Microbial Consortia from a Wastewater Treatment Plant

Area of Science:

• Environmental Microbiology
• Biotechnology
• Polymer Science

Background:

• Plastic waste is a global crisis, threatening ecosystems and human health.
• Current plastic recycling methods are inefficient, necessitating novel solutions.
• Enzymatic plastic degradation offers a pathway to a circular economy.

Purpose of the Study:

• To investigate the plastic-degrading capabilities of microorganisms from activated sludge (AS).
• To enrich microbial consortia capable of breaking down polylactic acid (PLA) and polyethylene terephthalate (PET) polymers.
• To identify plastic-active bacteria and their enzymes for potential biotechnological applications.

Main Methods:

• Enrichment of five microbial consortia from activated sludge (AS) using PET and PLA polymers.
• Incubation for 100 days at 37 °C and 50 °C under selective conditions.
• Metagenomic analysis, nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC) to assess degradation and microbial composition.

Main Results:

• Enriched microbiomes effectively degraded PLA polymers, evidenced by significant molecular weight reduction.
• Post-consumer PET was not degraded by the enriched microbiomes.
• Distinct microbial community shifts were observed at different temperatures, with *Bacillales* dominating at 50 °C.

Conclusions:

• Activated sludge microorganisms are a valuable source of polyester-degrading enzymes, especially PLA-depolymerases.
• The identified microbial communities show potential for biotechnological strategies in plastic waste mitigation.
• These findings support advancing re- and up-cycling approaches for plastic pollution reduction.