Soil microbes in the Tibetan Plateau degrade polyvinyl chloride and harbor novel dehalogenase SerB

Abstract

Polyvinyl chloride (PVC) stands as the third most widely produced synthetic polymer plastic. However, investigations into its microbial degradation significantly trail those of polyethylene (PE) and polystyrene (PS). Here, this study enriched a PVC-degrading consortium DC from the soil microbes of Tibet Plateau grasslands, confirming the formation of long-chain alkanes and the release of chloride ions via GC-MS and ion chromatography analysis. The response of DC to synthetic polymer PVC and natural polymer lignin revealed resistant polymer-response Burkholderia, opportunistic polymer-response Rhodococcus, and sensitive polymer-response Dyella. These PVC-degrading bacteria exist in 432 datasets of alpine meadows. Metaproteomic analysis highlighted distinct enzymatic profiles between PVC-DC and lignin-DC, with 298 proteins associated with PVC degradation compared to 123 proteins linked to lignin. Six key protein categories, including dehalogenase, peroxidase, monooxygenase, dioxygenase, esterase, and dehydrogenase, were involved in PVC degradation. An upregulated dehalogenase SerB from Rhodococcus, belonging to the clade of phosphoserine phosphatase, displayed proficiency in degrading chloroacetic acid and PVC films via hydrolytic dehalogenation. Furthermore, global metagenomic analysis from 38 datasets underscored the prevalence of dehalogenases and related enzymes in grasslands. This study elucidates the microbial responses and enzymatic pathways in PVC degradation, emphasizing the abundance of PVC-degrading enzymes in alpine ecosystems.