Denitrifying Microbial Communities in Heavy-Metal-Contaminated Paddy Soils near Electronic-Waste Processing Centers

Bacterial communities and denitrifiers in polluted paddy soils near e-waste processing centers were explored to investigate the effects of e-waste-derived heavy metals on soil bacteria. The abundance of denitrifying genes (narG, nirK, and nosZ), as well as the total bacterial community in soils, was slightly influenced by heavy metals. However, heavy metals, especially Ni and Cu, had a greater effect on the community structure of denitrifiers than other soil factors. Significant correlations were observed between heavy metals and the abundance of some dominant denitrifiers (P < 0.05). The Cu and Ni content had a significant positive effect on Methylobacterium based on the relative abundance of nitrite reducers to nitrous oxide reducers (P < 0.05). The exploration of the abundance and composition of denitrifiers in e-waste-contaminated paddy soils and their relationship with heavy metal content in soil offer an insight into the influence of heavy metals on denitrification in such soils.