Isolation of Polyethylene-Degrading Bacteria From Municipal Landfill Soil

Abstract

Polyethylene is among the most widely used plastics and one of the most persistent, and landfill soil is the place where much of it ends up. Because that soil also holds dense and varied microbial communities, it is a natural place to look for bacteria that can attack the polymer, and many reports describe isolates from such sites that appear to degrade polyethylene films. This narrative review asks what those reports establish. It draws on published work on polyethylene structure, oxidative breakdown, isolation from waste-impacted soil and the methods used to claim degradation, and it reports no new data from any landfill. The literature supports a cautious picture: abiotic weathering usually has to open the polymer before microbes can use it, biofilm formation is common, and a handful of genera recur among reported isolates. Yet much of the evidence rests on weight loss and surface imaging, which cannot separate consumption of the polymer backbone from loss of additives or growth on contaminants. Few studies include sterile and abiotic controls, label the carbon, or identify the enzymes involved. The review concludes that isolation from landfill soil is a sound starting point and that a convincing claim needs several independent lines of evidence, and it sets out what such a study would contain.