Metagenomic insights into potential PET hydrolases from Antarctic soils and rhizospheres

Abstract

Polyethylene terephthalate (PET) is a persistent synthetic polymer that is increasingly detected in terrestrial environments, where it influences soil microbial activity and carbon cycling. Microorganisms capable of hydrolyzing PET and related polyesters constitute a valuable enzymatic resource for developing low-temperature biocatalysts and for advancing the understanding of soil functional adaptation to plastic pollution. Here, we conducted a metagenomic analysis of soil and rhizosphere samples from the Antarctic vascular plants Deschampsia antarctica and Colobanthus quitensis, as sources of microbial enzymes with potential PET-hydrolytic activity. Hidden Markov Models constructed from experimentally validated PET hydrolases identified 152 putative PET hydrolases (pPETHs) spanning multiple protein families. Four candidates exhibited amino acid motifs characteristic of Ideonella sakaiensis PETase, including the conserved alpha/beta hydrolase fold and the Ser-His-Asp catalytic triad. One candidate from a Duganella genome also contained a tryptophan residue associated with efficient product release during PET hydrolysis. Molecular docking and molecular dynamics analyses revealed that candidates retain the core catalytic architecture of established PET hydrolases, while simultaneously displaying structural signatures of cold adaptation. These findings demonstrate the diversity of PET-hydrolase-like genes within Antarctic rhizosphere and soil microbiomes, broadening the current understanding of microbial enzymatic potential under cold, oligotrophic conditions. The identified sequences highlight the rhizosphere as a reservoir of functional diversity relevant to soil biotechnology, cold-adapted catalysis, and microbial strategies for transforming recalcitrant carbon substrates.