Nanoplastic and phthalate induced stress responses in rhizosphere soil: Microbial communities and metabolic networks

The widespread use of plastic products in agriculture has introduced micro-nano plastics (MNPs) and dibutyl phthalate (DBP) into soil ecosystems, disrupting microbial communities and altering metabolite profiles. However, their effects on the rhizosphere soil characteristics of medicinal plants like dandelion remain understudied. This study systematically examined the impact of PS NPs and DBP on rhizosphere microbial communities and metabolites by integrating high-throughput sequencing with liquid chromatography-mass spectrometry. Results demonstrated that individual and combined exposures to PS NPs and DBP decreased soil pH, organic matter content, and enzyme activities while reshaping the diversity, structure, and composition of rhizosphere bacteria and fungi. Notably, bacterial network stability and complexity increased under combined exposure, while fungal networks became more simplified, with a 33.72 % decrease in positive correlations. We identified potential PS NPs and DBP-degrading bacteria and biomarkers, including Nocardioides, Pseudarthrobacter, and Arenimonas. We revealed that co-exposure elevated differential soil metabolites associated with tyrosine metabolism and steroid biosynthesis. The significant positive associations between rhizosphere microorganisms and metabolites highlighted that metabolite accumulation was a key microbial response mechanism to stress. However, within the complex soil environment, the compensatory actions of microorganisms and metabolites were insufficient to mitigate the detrimental effects of PS NPs and DBP, resulting in continued inhibition of dandelion growth by 38.66 %. Consequently, these findings highlight that soil fungi and metabolism play key roles in responding to stress and influencing crop growth, providing novel insights into the impact of nanoparticle and plasticizer exposure on medicinal plant cultivation.