Enrichment of Microbes Potentially Degrading Polyethylene Using a Microcosm Approach

Abstract

Plastic pollution is a worldwide phenomenon with concerning effects on the biosphere and particularly on the marine environment. Biodegradation is considered an environmentally friendly alternative to combat the increasing quantities of plastic pollutants where different microbial sources are tested for plastic degradation potential. In this project, a microcosm approach was used as an enrichment method for marine microbes degrading polyethylene. Pieces of low-density polyethylene (LDPE) and highdensity polyethylene (HDPE) previously deployed in ocean water have been explored as a source of microbial biomass. This source plastic was added to a synthetic medium containing sterilized pieces of LDPE and HDPE as the sole carbon source and were incubated for extended periods (32-86 days) in the laboratory to promote growth of microbes that can degrade plastic. Biodegradation of polyethylene was confirmed by dry weight measurements and Fourier Transform Infra-Red (FTIR) spectroscopy. For both LDPE and HDPE a significant reduction in dry weight was observed. FTIR analysis
showed peaks suggesting oxidative changes in polyethylene’s chemical composition. In summary, the microcosm approach can be considered a viable approach for enrichment of plastic-degrading marine microbial populations.