Environmental implication of MoS₂ nanosheets: Effects on maize plant growth and soil microorganisms

Molybdenum disulfide (MoS₂) nanosheets have been used extensively in a variety of fields including medical and industrial. However, little is known about their toxicity effects, especially to edible plants. In this greenhouse study, maize (Zea mays) seedlings were exposed for 4 weeks, through the soil route, to 10 and 100 mg/kg of 2H MoS₂ nanosheets. Plant growth, physiological parameters (chlorophyll, antioxidants, and MDA), along with Mo and nutrient element contents were determined in plant tissues. Results showed that at both doses, the nanosheets decreased plant growth. Inductively coupled plasma-mass spectrometry data also showed that both 2H MoS₂ concentrations allowed Mo absorption and translocation by maize plants. Additionally, at 100 mg/kg the nanosheets significantly reduced Ca, Mg, Mn, and Zn in leaves, and Na in roots. Gene sequencing data of 16S rRNA showed, that MoS₂ nanosheets changed the soil microbial community structure, compared with the untreated control. In addition, nitrogen-fixing microorganisms such as Burkholderiales, Rhizobiales and Xanthobacteraceae were enriched. Overall, the data suggest that, even at low dose (10 mg/kg), the 2H MoS₂ nanosheets perturbed both the nutrient uptake by maize plants and the soil microbial communities.