CuO nanoparticles were studied to see how they affect the bacteria in the soil and nitrogen levels for wheat plants. The researchers found that the nanoparticles changed the bacterial community in the soil and affected nitrogen cycling. When wheat plants were exposed to CuO nanoparticles, the nitrate levels in the soil changed, with different effects in the bulk soil compared to the soil near the plant roots. The presence of CuO nanoparticles influenced the genes related to nitrogen cycling in the soil, affecting processes like nitrogen fixation and denitrification. This study shows that nanoparticles can have complex effects on soil bacteria and nitrogen levels, which are important for plant growth.