Dynamic interplay between microbial denitrification and antibiotic resistance under enhanced anoxic denitrification condition in soil

- Co-polluted soil with antibiotics and nitrogen has become a potential threat.
- Antibiotic presence significantly inhibited the denitrification process in soil.
- Enforced denitrification prompted the decline in antibiotic and ARG levels.
- The higher the DNG level, the more dramatic was the progression of denitrification.
- Clearly negative correlation was detected between DNG and ARG abundance.

Mixed contamination of nitrate and antibiotics/antibiotic-resistant genes (ARGs) is an emerging environmental risk to farmland soil. This is the first study to explore the role of excessive anthropogenic nitrate input in the anoxic dissipation of soil antibiotic/ARGs. During the initial 10 days of incubation, the presence of soil antibiotics significantly inhibited NO3− dissipation, N2O production rate, and denitrifying genes (DNGs) abundance in soil (p < 0.05). Between days 10 and 30, by contrast, enhanced denitrification clearly prompted the decline in antibiotic contents and ARG abundance. Significantly negative correlations were detected between DNGs and ARGs, suggesting that the higher the DNG activity, the more dramatic is the denitrification and the greater are the antibiotic dissipation and ARG abundance. This study provides crucial knowledge for understanding the mutual interaction between soil DNGs and ARGs in the enhanced anoxic denitrification condition.

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