Exploring the plastic biodegradation potential within microbial lineages and across global ecosystems

Abstract Plastic waste pollution is a global issue that threatens biodiversity and human health. Current plastic waste management practices are not sufficient to keep up with increasing plastic production rates. Microorganisms have the capacity to degrade different types of bio-based and synthetic plastics through enzymatic reactions, offering an alternative solution to traditional plastic recycling techniques. A limited number of plastic-degrading enzymes have been identified, sequenced and characterised, however, studies exploring the distribution of homologs of these enzymes across habitats and microbial taxa have remained scarce. Here, we applied analytical techniques to search for potential plastic-degrading enzymes in environmental metagenomic datasets and the Genome Taxonomy Database (GTDB) to explore the geographic and taxonomic distribution patterns of plastic-degrading microorganisms. Hidden Markov Models (HMMs) were constructed from known, experimentally verified and putative plastic-degrading enzyme sequences. The HMMs were applied to landfill, soil, river, lake and ocean metagenomes and all archaeal and bacterial genomes in the GTDB. An abundance of plastic-degrading enzyme hits were discovered across the aquatic and terrestrial metagenomes with the majority occurring in polluted rivers, polar oceans and deep ocean samples. GTDB hits were consistent with known plastic-degrading microbial lineages. Additionally, potential plastic-degrading archaeal lineages were identified. The results of this study may be able to assist in the discovery of novel plastic-degrading enzymes for application in plastic waste biodegradation solutions. Repository contents 1_Enzymes and HMMs summary.xlsx Tables with information on the seed enzymes and HMMs 2_Seed_enzymes.faa Seed enzymes amino acid sequences 3_GraftM_packages.tar Folder containing the HMM packages created with GraftM. Note: all HMM packages are included, even those which did not meet the acceptance criteria of Precision > 0.95. The HMMs with Precision < 0.95 have an "x" prefix in the outer folder name, e.g. "xA0A0D3MTJ6".