Bacteria

Biology

Materials science

Chromatography

Biodegradation

Mesophile

Decomposition

Pellets

Genetics

Organic chemistry

Microplastics

Polyethylene

Environmental chemistry

Gas chromatography

Composite material

Chemistry

Chemosphere

In this study, we investigated the decomposition of micro-sized polyethylene (PE) by mesophilic mixed bacterial culture isolates obtained from a municipal landfill sediment. Among these, Bacillus sp. and Paenibacillus sp. were more specifically enriched in the non-carbonaceous nutrient medium (i.e., Basal medium) as they were the most dominant species when they were exposed to PE microplastics. They reduced the dry weight of particles (14.7% after 60 d) and the mean particle diameter (22.8% after 60 d; obtained by field-emission scanning electron microscopy analysis). In the gas chromatography-mass spectrometer analysis of biologically aged particles, the amount and types of organic contents eluted from the PE microplastics were far lower in the early decomposition phase; however, they increased in the later phase. Thermal gravimetric analysis showed that the aged particles had higher thermal stability at temperatures greater than 570 °C compared to the control, thereby suggesting that microplastics were degraded by enzymatic chain scission, which could in turn be ascribed to the greater refractory fractions of aged particles remaining at a high combustion temperature. It was further verified that PE particles could be biologically utilized as a sole carbon source and broken down during the test period.

Biodegradation of micro-polyethylene particles by bacterial colonization of a mixed microbial consortium isolated from a landfill site