Unravelling the plastisphere-soil and plasticplane microbiome of plastic mulch residues in agricultural soils

Advances in molecular techniques have recently uncovered microbial communities associated with plastic debris. The term ‘plastisphere’, was originally used for microbial communities on marine plastic. In terrestrial systems, this term has been extended to the plastic-soil interface, encompassing microbes from the surrounding soil. Although some studies have revealed differences in microbial composition and diversity between plastisphere and bulk soil, high-resolution spatial analyses of microbial communities on the immediate plastic surface (plasticplane) and in the attached soil (plastisphere-soil), are still lacking. In this study, a methodology was developed to disentangle the bacterial populations associated with the plastisphere-soil of weathered plastic mulch from agricultural fields from those on the plasticplane by using culture-based and High-Throughput sequencing approaches. A significantly higher number of colony-forming units were cultured from the plastisphere-soil compared to the plasticplane. Main genera isolated from the plasticplane by culturing included Arthrobacter, Pseudarthrobacter, Priestia, Massilia, Microbacterium, Bacillus , and Kocuria genera, some of which are known plastic-degraders. High-throughput sequencing analysis revealed higher bacterial richness in plastisphere-soil, while beta diversity showed main significant differences among field plots. Core taxa significantly associated to the plasticplane included Bacillus , Sphingomona s, Nocardioides, and Solirubrobacter . This study provides a pioneering description of a methodology to differentially analyze microbial communities at different soil-plastic interfaces, particularly on a small spatial scale using samples from plastic mulch residues in agricultural soils. This methodology may lay a foundation for future research to isolate and identify microbial plastic degraders, contributing to efforts against mitigating plastic pollution. • Method developed to assess microbial communities on plastic-associated compartments. • Key plastic-associated bacteria from natural samples were isolated and identified. • Higher species richness in the plastisphere-soil compared to the plastic surface. • Plastic additives could influence the associated microbial communities. • A core plasticplane bacterial community was identified across all field sites.