GAINING INSIGHTS IN THE MICROBIAL DEGRADATION OF POLYETHYLENE PLASTICS

Plastics production, use and degradation are hot topics that have come to the forefront over recent years. Polyethylene (PE) represents more than 60% of all petroleum-derived plastics worldwide and is accumulating at rates of several millions of tons per year because of its strong recalcitrance to biotic and abiotic degradation. Microbial degradation has been proposed as a possible alternative way to reduce plastic wastes. The general aim of this work was the identification of bacterial strains able to metabolize PE and to identify the biochemical pathways of this biodegradation process. In an abandoned landfill we collected different plastic samples; using a metagenomic approach, we found a strong relationship between the plastic properties (including the presence of colorants) and the microbial community By screening the natural microbial community exposed to PE in environment, we isolated 10 bacteria which revealed the ability to grow on PE as only energy and carbon source. A bacterium, Pseudomonas aeruginosa UC4003, showed the highest growth rate in minimal salt medium and polyethylene. When grown on PE, this strain produced an extracellular enzyme, protein-like activator for n-alkane oxidation (PA), involved in the first step of polyethylene degradation.