Nanoplastics indirectly compromise lettuce growth in hydroponic systems via microbial extracellular vesicles derived from Curvibacter fontanus

Recent studies confirm that nanoplastics (NP) cause severe microbial imbalances in various ecosystems, significantly affecting microbial diversity and abundance. Hydroponic systems vital for lettuce production are increasingly threatened by NP contamination in irrigation water and this issue is gaining global attention. This study investigates microbial species in hydroponic irrigation water altered by NP exposure and their impact on lettuce growth. While NP (10⁸-10¹⁰ particles/L) did not directly harm or accumulate in lettuce, significant changes in water parameters and microbial communities were observed, particularly an increase in Curvibacter fontanus abundance. Inoculation of sterile irrigation water with NP and C. fontanus led to lettuce mortality, suggesting C. fontanus as a critical mediator. Furthermore, extracellular vesicles (EVs) isolated from C. fontanus, treated with NP, were shown to suppress leaf development, growth, antioxidant defenses, and lettuce survival. This study concludes that NP-induced microbial shifts, particularly involving C. fontanus EVs, indirectly harm hydroponic lettuce production.