Dissolved oxygen disturbs nitrate transformation by modifying microbial community, co-occurrence networks, and functional genes during aerobic-anoxic transition.

Abstract No consensus has been achieved among researchers on the effect of dissolved oxygen (DO) on nitrate (NO3−-N) transformation and the microbial community, especially during aerobic-anoxic transition. To supplement this knowledge, NO3−-N transformation, microbial communities, co-occurrence networks, and functional genes were investigated during aerobic-anoxic transition via microcosm simulation. NO3−-N transformation rate in the early stage (DO ≥2 mg/L) was always significantly higher than that in the later stage (DO