Insights into the shift of microbial community related to nitrogen cycle, especially N2O in vanadium-polluted soil

Abstract

Soil is a vital contributor to the production of nitrous oxide (N₂O), a potent greenhouse gas, through the nitrogen cycle, which can be influenced by accumulated vanadium (V) in soil but it is less pronounced. This work investigated the response of soil N₂O fluxes along with major nitrogen cycle products (ammonium, nitrate, and nitrite) to different vanadium contents (0, 200, 500, 800, and 1100 mg V/kg), and the underlying microbial mechanisms. N₂O fluxes was significantly influenced at high V content (1100 mg V/kg) due to its corresponding high water-soluble V content. Microbial composition and their correlations with nitrogen cycle products showed that microbes in dominant phyla (Actinobacteriota and Proteobacteria) and genus (Nocardioides, Lysobacter, Sphingomonas, and Marmoricola) might be the important contributor to N₂O fluxes regardless of the V content. Moreover, high V contents (800, and 1100 mg V/kg) could enrich microbes involved in nitrogen cycle, but weaken their correlations with nitrogen-related products, such as in genus Bacillus, and change microbial correlation with N₂O from associated with nitrate and nitrite to ammonium. Meanwhile, functional gene predication results showed that denitrifying genes nirKS and nosZ were negatively and positively correlated with V contents, respectively. These all further suggested that the shift of possible N₂O metabolic pathways induced mainly by water-soluble V might be the underlying reason for N₂O fluxes. These findings promote an understanding of the potential effect of metal pollution on N₂O fluxes in soil.

Keywords: Greenhouse gas; Microbial community; Nitrous oxide; Soil nitrogen cycle; Vanadium forms.