Methanogenic response of paddy soils exposed to zinc oxide nanoparticles and sulfurized products

The use of zinc oxide nanoparticles (ZnO NPs) in agriculture is expanding, yet their effects on microbial ecology in flooded paddy soils remain unclear. This study examined the influence of ZnO NPs and their sulfide derivatives (S-ZnO NPs) on methane production in paddy soils. Results showed that ZnO NPs at a concentration of 1000 mg/kg significantly inhibited methane production by 28.97 % in an acid soil and by 26.83 % in an alkaline soil. S-ZnO NPs at the same concentration did not significantly affect methane production in the alkaline soil and increased it by 15.33 % in the acid soil. High-throughput sequencing revealed that ZnO NPs significantly altered the microbial community structure, affecting the prevalence of methanogenic organisms like Methanosarcina in the acid soil and Methanobacterium in the alkaline soil. Quantitative PCR analysis showed a reduction in the expression of methanogenic gene (mcrA) and total bacterial 16S rRNA genes with ZnO NPs exposure, but S-ZnO NPs had a lesser impact on these genes. This research highlights the more toxic impact of ZnO NPs compared to S-ZnO NPs on methane production and microbial communities in paddy soils, emphasizing the necessity for careful evaluation of nanoparticles in agricultural use to avoid ecological disturbances.