Genomic Comparison and Enzymatic Characterization of Dienelactone Hydrolase in Actinopolyspora saharensis Bacteria for Petroleum-Based Plastic Bioremediation

Abstract

An in silico genomic comparison was conducted between two Actinopolyspora saharensis strains, H32^T and BKK2, originating from Algeria and China, respectively. The DNA-DNA hybridization value was 90.9%, while average nucleotide identities ranged from 98.74 to 99.04%, confirming both strains as the same genospecies. The comparative genome analysis identified six shared biosynthetic gene clusters (BGCs). CAZyme annotation revealed glycoside hydrolases (GHs) and glycosyltransferases (GTs) as the most abundant enzymatic families. The core genome accounted for only 11.83% of the total pangenome, while the shell genome comprised nearly 90% of genes. Furthermore, an in silico analysis of the physicochemical properties of dienelactone hydrolase (DLH) from A. saharensis was conducted. The DLH demonstrated potential in biorecycling by degrading polyethylene terephthalate (PET) monomers such as bis(2-hydroxyethyl) terephthalate (BHET), providing eco-friendly solutions to reduce plastic accumulation through protein engineering. The enzyme’s 3D structure was predicted, optimized, and validated using multiple computational methods. To assess its catalytic potential, molecular docking analyses were performed with polyethylene terephthalate (PET) degradation intermediates, namely mono(2-hydroxyethyl) terephthalate (MHET), bis(2-hydroxyethyl) terephthalate (BHET), terephthalic acid (TPA), and ethylene glycol (EG). Since PET is a synthetic polymer derived from petroleum, the strong and stable binding interactions observed, particularly with BHET and MHET, suggest that the DLH of A. saharensis could play a key role in the biodegradation of petroleum-based plastics. This study highlights the biotechnological potential of the DLH from A. saharensis for environmental and industrial applications, particularly in the bioremediation of petroleum-derived plastic waste.