Microplastic polymer properties as deterministic factors driving terrestrial plastisphere microbiome assembly and succession in the field

Environmental microplastic (MP) is ubiquitously detected in aquatic and terrestrial ecosystems providing artificial habitats for microbes. Mechanisms of MP colonization, MP polymer impacts, and effects on soil microbiomes are largely unknown in terrestrial systems. Thus, we experimentally addressed the hypothesis that MP polymer type is a major deterministic factor impacting MP community assembly by incubating common MP polymer types in situ in landfill soil for 14 months. 16S rRNA gene amplicon sequencing indicated MP polymer specific impacts on MP microbiomes representing subsets of the soil microbiome. Chloroflexi, Gammaproteobacteria and certain Cren- and Nanoarchaeota explained differences among MP polymers and time points. Potentially pathogenic taxa were enriched in the plastisphere. Microbial community composition derived from different MP diverged over time. PICRUSt predictions of functional potentials and quantitative PCR of functional marker genes suggested that MP polymers exerted an effect on genetic toluene degradation and methane emission potentials. Collectively, the data indicates that (i) polymer type as deterministic factor rather than stochastic factors drives plastisphere community assembly, (ii) MP impacts greenhouse gas metabolism, xenobiotic degradation and pathogen distribution, and (iii) MP serves as an ideal model system to study fundamental questions in microbial ecology such as community assembly mechanisms in terrestrial environments.