Biodegradation of 13C-Labeled and Nonlabeled Aliphatic-Aromatic Polyesters in Compost: Advancing Assessments through...

Area of Science:

• Environmental Science
• Polymer Science
• Microbiology

Background:

• Standard polymer biodegradability tests in industrial compost often use high polymer concentrations and only measure CO2 production.
• This approach may not fully capture the fate of all polymer carbon, potentially underestimating biodegradation.

Purpose of the Study:

• To develop and validate a method for tracking both mineralized and non-mineralized polyester carbon in compost.
• To assess the accuracy of standard biodegradability tests by comparing them with a more comprehensive approach.

Main Methods:

• Utilized 13C-labeled polyesters (PBAT, PBSeT) in compost incubations at low concentrations.
• Tracked 13C in both mineralized (CO2) and non-mineralized fractions.
• Analyzed residual polyester using solvent extraction and proton nuclear magnetic resonance (1H NMR) spectroscopy.

Main Results:

• Low-concentration incubations with 13C-labeled polyesters showed shorter lag-phases and higher relative mineralization rates compared to high-concentration incubations.
• Mass balance assessments confirmed accurate tracking of 13C in all pools.
• Substantial incorporation of polyester carbon into microbial biomass was observed, indicating incomplete mineralization.

Conclusions:

• Standard biodegradability tests relying solely on CO2 measurements may underestimate the true biodegradation of polymers in compost.
• The metabolic capacity of compost microbial communities can be exceeded by high initial polymer concentrations.
• A comprehensive tracking approach, including non-mineralized fractions and biomass incorporation, provides a more accurate assessment of polymer biodegradation.