Microplastic–Bacteria Interactions: Toxicity, Colonisation, Degradation and Prospects

ABSTRACT

Microplastics (MPs) have established complex bidirectional interactions with bacteria, encompassing both mutualism and antagonism. This review advances a unified ‘Stress‐Habitat‐Degradation’ triangular model that systematically integrates three interconnected dimensions: (1) MPs‐induced biotoxic stress on bacterial communities in water, soil, guts and plant tissues; (2) the plastisphere as a colonisation substrate that enriches pathogens and facilitates ARG spread; and (3) enzymatic biodegradation by functional taxa like Pseudomonas via specific enzymatic pathways. This framework explicitly links microbial community dynamics to functional outcomes, demonstrating that the same MPs–bacteria interplay simultaneously drives toxicity/pathogen enrichment and beneficial degradation. Environmental factors (temperature, oxygen, soil organic matter) profoundly shape these interactions by regulating gene expression and community succession. Crucially, we identify and resolve apparent contradictions—such as differential Gram‐positive/Gram‐negative responses and conflicting diversity trends—by attributing them to variations in polymer type, particle size, concentration, exposure time, host species and test conditions. Overall, this synthesis provides a critical integration of MPs‐bacterial interactions and proposes a novel pollution control strategy centred on these interactions, redefining environmental risk assessment and bioremediation approaches.