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

Wide contamination of MPs including polyvinyl chloride (PVC) has been reported in remote regions such as Qinghai-Tibet Plateau (QTP). Microbial degradation of plastics is frequently coupled with lignocellulose-degrading enzymatic machinery. Given its status as a widespread biological sampler in QTP, the Tibetan herbivore plateau pika (Ochotona curzoniae), which harbors lignocellulose-degrading enzymes, represent a promising reservoir for novel PVC-degrading enzymes. In this study, a polyvinyl chloride (PVC)-feeding trial of Tibetan plateau pikas (Ochotona curzoniae) 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 haloalkane dehalogenase RhHLD (from Rhodococcus MAG) released 11.5 mg/L chloride ions from PVC films, whereas dye-decolorizing peroxidase LeDyP from Leifsonia MAG generated PVC degrading intermediates. Further analysis of 39 metagenomic datasets confirmed that haloalkane dehalogenase and dye-decolorizing peroxidase are prevalent in wild pikas gut. This study elucidates the PVC-degrading potential of herbivore gut microbiota and expands the catalytic toolkit for plastic bioremediation, opens new avenues for enzyme discovery in natural ecosystems.