Microplastics as Ecological Filters Across Food Systems: From Microbial Selection and Antimicrobial Resistance to Human Health Risks and Mechanisms

Microplastics are increasingly detected throughout food-production systems, from agricultural soils and irrigation waters to aquaculture environments, food-processing facilities, and final food products. Beyond their role as contaminants and microbial carriers, plastic particles provide persistent surfaces for biofilm development and may selectively shape the microorganisms and functional traits that persist during environmental transport. This review introduces an ecological-filter framework for understanding the microbiological significance of microplastics across food systems. We examine how polymer properties, conditioning films, weathering, environmental gradients, ecological succession, and colonization history interact to drive plastisphere assembly and microbial community turnover. Particular attention is given to the hypothesis that mature plastisphere biofilms may provide temporary microenvironmental buffering during transitions between physicochemically distinct environments, potentially facilitating microbial acclimation and selective persistence. We further evaluate evidence for the enrichment, expression, and horizontal transfer of antimicrobial resistance determinants within plastisphere communities and distinguish these processes from simple microbial carriage. Analytical approaches are critically examined through an evidence hierarchy spanning taxonomic detection, functional potential, transcriptional and protein expression, phenotype, food occurrence, and demonstrated health outcomes. Although current evidence supports selective microbial and resistome restructuring on microplastics, direct links between environmental plastisphere selection, persistence in food products, dietary exposure, and human-health effects remain limited. We therefore propose that microplastics in food systems should be considered dynamic ecological habitats undergoing sequential filtering rather than passive vectors carrying stable microbial communities. Integrating microbial ecology, multi-omics, spatial analyses, cultivation, and food-chain tracking will be essential to determine when plastisphere-mediated ecological selection translates into meaningful food-safety risk.