Investigation of the ecological roles of the plastisphere microbiome in metal-contaminated river sediments: elucidation of their metabolic versatilities for plastics mineralization and metal resistance

Both plastic and heavy metal(loid)s (HMs) are ubiquitous environmental contaminants, and their frequent interactions in aquatic environments are observed globally. These interactions could result in adsorption of HMs onto plastics, thereby altering the environmental behavior of both contaminants. The change of physicochemical property of plastics surfaces, due to HM adsorption, inevitably impacts the plastisphere microbiome, as well as the fate of plastics in the environment. However, our understanding of how plastisphere microbiome respond to HMs stress, and the subsequent impacts on the fate of plastics and HMs, remain in its infancy. The current study identified keystone taxa of the plastisphere microbiome and identified their ecological roles in HM metabolism. Members of Mycobacterium were identified as the keystone taxa in the HM contaminated plastisphere. Metagenomic binning and pangenome analysis demonstrated that Mycobacterium encoded essential genes for plastic biodegradation and HM resistance.