The plastisphere: not a unique biofilm but a unifying concept for the interdisciplinary plastic biofilm research community.

Plastic has introduced a novel and persistent substrate into natural ecosystems, rapidly colonized by microbial biofilms collectively termed the plastisphere. Since its introduction, the concept has catalyzed interdisciplinary research and shaped scientific and public discourse on plastic pollution. Yet, a central question remains unresolved: Do plastisphere communities represent a fundamentally distinct ecological entity, or are they conventional biofilms forming on an unconventional material? Here, we synthesize current evidence across marine and terrestrial systems to argue that plastisphere communities are not consistently taxonomically or functionally unique. Instead, they largely reflect established biofilm assembly processes governed by environmental conditions, source communities, and successional dynamics. Claims of plastic biodegradation, pathogen enrichment, or antimicrobial resistance hotspots remain context-dependent and often lack robust comparative frameworks. We propose that the ecological significance of the plastisphere lies not in microbial novelty, but in the properties of the substrate itself. Plastics are uniquely persistent and, in many environments, highly mobile, enabling microbial communities to disperse across ecosystems and extend residence times beyond those of natural particles. By reframing the plastisphere as a condition of microbial life on durable, mobile substrates, we retain its conceptual value while aligning it with ecological theory and advancing a more precise research agenda.