Untapped enzymatic potential: dehalogenase- and peroxidase-driven PVC degradation by gene carriers in Tibetan plateau pikas.

BACKGROUND: Wide distribution of polyvinyl chloride microplastics (PVC-MPs) has been documented in remote regions such as the Qinghai-Tibet Plateau (QTP). Microbial degradation of plastics is frequently coupled with lignocellulose-degrading enzymatic machinery. As a ubiquitous biological sampler on the QTP, the herbivore plateau pika (Ochotona curzoniae), which harbors diverse lignocellulose-degrading enzymes, represents a promising reservoir for novel PVC-degrading enzymes. RESULTS: In this study, a PVC-MPs feeding trial of plateau pikas revealed gut microbiota recruitment of plastic degraders. Subsequent enrichment experiment yielded a PVC-degrading consortium that depolymerized PVC into long-chain alkanes, with Rhodococcus and Leifsonia identified as PVC-response specialist and generalist, respectively. Multi-omics analysis supported a putative degradation pathway initiated by haloalkane dehalogenase (HLD) and involving oxidases. Furthermore, novel RhHLD (from Rhodococcus MAG) released 11.5 mg L-1 chloride ions from PVC films, whereas dye-decolorizing peroxidase LeDyP from Leifsonia MAG generated PVC-degrading intermediates. Analysis of 39 metagenomic datasets further confirmed that haloalkane dehalogenase and dye-decolorizing peroxidase are prevalent in the gut of wild pikas. CONCLUSIONS: This study elucidates the PVC-degrading potential of herbivore gut microbiota and expands the catalytic toolkit for plastic bioremediation, underscoring the bioprospecting potential in extreme ecosystems Video Abstract.