Researchers at Seoul National University demonstrated that the toxicity of microplastics can vary depending not only on particle properties but also on the bacterial strains present alongside them. Using Caenorhabditis elegans, the team showed that Enterobacter sp. LG3 aggravated physiological stress and intestinal accumulation of polystyrene microplastics, whereas Bacillus sp. SCGB1 alleviated these effects. The study further suggested that strain-specific interactions, including biofilm formation and metabolite-linked host responses, play a key role in shaping microplastic toxicity. This work provides a new framework for assessing microplastic risk and suggests the potential of microbiome-based mitigation strategies.