Evaluation of Genes and Enzymes from Microorganisms Involved in The Biodegradation Of Polyethylene-based Plastics

One of the most ubiquitous and long-lasting challenges of plastic waste management is polyethylene (PE) accumulation, posing a major ecological threat to our planet. The aim of this study is to find microorganisms and enzymes involved in polyethylene biodegradation as well as the genes (and operons) from the metagenomes of these degraders.For this purpose, soil sample from three areas with accumulation of plastic waste with different climates (dry-desert, semi-arid and temperate) were sampled. Two approaches were used: culture-based screening and functional metagenomics.In the culture-based approach, 20 bacterial and 3 fungal isolates were identified by sequencing of 16S rDNA from bacterial genomes and ITS from fungal genomes. The presence of laccase and peroxidase enzymes in these isolates have been assayed with ABTS and Guaiacol as substrates. All isolates have shown appropriate enzyme activity for polyethylene biodegradation.In the metagenomics-based approach, soil DNA was extracted; construction and screening of metagenomic fosmid libraries were carried out as a source of potential polyethylene degrader genes/operons and 750 out of 2600 clones tested positive through hexadecane biodegradation screening (as a model substrate). The viability and degradability potential of positive clones are presently being verified using polyethylene as the sole carbon source.