Metagenomic profiling of plastic-degrading microbial communities in urban water bodies
Abrar, Md. Danial Dirar, Saad Bin Sohan, Swakkhar Shatabda (supervisor)
abstract › Urban freshwater bodies accumulate large amounts of plastic pollution, yet the microbial genetic capacity to degrade these polymers in such environments remains poorly characterized. This ongoing study performs a conservative, thesis-grade screen for putative plastic-degrading enzymes in a polluted freshwater sediment metagenome (NCBI SRA accession SRR23872596), reporting genetic potential and homology-based inference rather than confirmed degradation. Sequencing reads are screened against a curated UniProtKB reference set of PETase-, MHETase-, cutinase-, AlkB-, and polyesterase-like enzymes using translated homology search (DIAMOND blastx) under strict thresholds (e-value ≤ 1e-5, ≥ 30% identity, ≥ 50 aa alignment length). Best-hit protein accessions are mapped to genus-level taxonomy to build genus–enzyme abundance matrices (raw and CPM-normalized), which are then clustered with k-means (k selected by silhouette) and organized into putative functional modules via a cosine-similarity genus network with Louvain community detection. The fully reproducible pipeline outputs enzyme–genus heatmaps, PCA and clustering figures, and modularity networks that together map which microbial genera co-carry plastic-degrading potential in urban water sediments. All results represent genetic potential only; homology-based inference cannot confirm enzymatic activity or plastisphere association.