Microplastics and microbial interactions in marine environments: A critical review on biogeochemical cycling and ecological impacts

Marine microplastic pollution has emerged as a critical global environmental challenge, exerting multifaceted impacts on marine ecosystems through intertwined physicochemical and biological processes. This review integrates bibliometric analysis (2015-2025) with mechanistic synthesis to examine the bidirectional interactions between microplastics and marine microorganisms. Microplastics provide persistent substrates that foster plastisphere formation, reshape microbial community structure, and enhance biofilm development, while also serving as vectors for pollutants and antibiotic resistance genes. In turn, microorganisms regulate the environmental fate of microplastics through biofilm-mediated aggregation, enzymatic degradation, and surface transformation. These processes profoundly influence marine biogeochemical cycles-particularly carbon, nitrogen, phosphorus, and sulfur fluxes-with cascading effects on productivity, nutrient dynamics, and ecosystem stability. Despite growing evidence, key gaps remain in linking molecular-level mechanisms to ecosystem-scale outcomes, especially in deep-sea and sedimentary habitats. Future progress requires multidisciplinary approaches coupling multi-omics, sedimentary microbiology, and synthetic biology to accelerate the discovery and optimization of microbial consortia capable of effective plastic degradation under realistic marine conditions. Advancing such integrative research is vital for predicting the long-term fate of microplastics and informing strategies for marine pollution mitigation and ecological restoration.