Lactobacillus plantarum reduces polystyrene microplastic induced toxicity via multiple pathways: A potentially effective and safe dietary strategy to counteract microplastic harm

Plastic materials, ubiquitous in daily life, degrade into microplastics (MPs) that can accumulate in humans through the food chain, leading to health issues. While some antioxidants have been shown to mitigate the toxicity caused by MPs exposure, they are only effective at high doses, which can be harmful to human health when ingested in excess. Concurrently, Lactobacillus species have demonstrated the ability to adsorb onto micro- and nano-plastics (MNPs), with certain strains exhibiting high antioxidant activity. In this study, Lactobacillus plantarum strains with varying antioxidant capacities and affinities for polystyrene nanoparticles (PS-NPs) were utilized to investigate their effects on toxicity induced by exposure to PS-MPs. The results indicated that the antioxidant capabilities of Lactobacillus plantarum can reduce oxidative damage caused by PS-MPs exposure, and their ability to bind with PS-MNPs can reduce the body's PS-MPs content and increase fecal PS-MPs content, thereby reducing toxicity. Notably, the strain 89-L1, which possesses low antioxidant activity and low binding affinity for PS-MNPs, also reduced toxicity, potentially through repairing the intestinal barrier and modulating bile acid (BAs) metabolism. Our findings suggest that the mechanisms by which Lactobacillus plantarum reduces PS-MPs-induced toxicity extend beyond antioxidant and binding capabilities; the repair of the intestinal barrier and modulation of BAs metabolism also play significant roles in reducing toxicity caused by PS-MPs exposure and may act partially independently of these capacities. This study provides a theoretical basis for the future development of strategies for Lactobacillus plantarum to reduce toxicity caused by exposure to MPs.