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<p>As an emerging pollutant widely present, antibiotics pose a potential threat to biological wastewater treatment. However, studies on the impact of mixed antibiotics on biologicalnitrogen removal are limited. Three norfloxacin (NOR)-oxytetracycline (OTC) ratios (R1-R3) were established using the direct equipartition ray method and uses high-throughput sequencing technology and PICRUSt2 to evaluate the impact of mixed antibiotics at different concentrations on nitrogen removal efficiency, microbial community structure, and metabolic functions. The results show that the inhibitory effect of mixed antibiotics on nitrogen removal efficiency increases with concentration. Low-concentration mixed antibiotics (≤ 10&#xa0;mg/L) have a negligible impact on biological nitrogen removal performance, whereas high-concentration mixed antibiotics (≥ 10&#xa0;mg/L) severely affect it. Specifically, compared with the blank group, in the high-concentration group, effluent NH<sub>4</sub><sup>+</sup>-N increased from 0.91&#xa0;mg/L to 23.58–29.34&#xa0;mg/L, while COD increased from 27.75&#xa0;mg/L to 277.38-307.31&#xa0;mg/L. High-throughput sequencing showed that, as the concentration of mixed antibiotics increased, the relative abundance of key denitrifying bacteria (<i>Thauera</i> and <i>Hydrogenophaga</i>) significantly decreased. Co-occurrence network analysis indicates that antibiotic mixtures with similar concentrations promote the enrichment of core nitrogen cycling groups and induce new community defense mechanisms. PICRUSt2 functional prediction showed that mixed antibiotics primarily inhibited the synthesis of microbial ABC transporters, Amino acid biosynthesis and Two-component systems, collectively disrupting microbial protein synthesis and proliferation, thereby reducing nitrogen removal efficiency. This study clarifies the mechanistic effects of mixed antibiotics on microbial metabolic pathways and provides a theoretical basis for the risks of emerging pollutants in biological wastewater treatment.</p>

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Mechanisms of microbial community restructuring and metabolic pathway modulation during biological nitrogen removal in livestock wastewater under combined antibiotic stress

  • 期刊论文

  • 发表日期：

    2026年1月8日

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  • Xianjin Qiu,
  • Jian Huang,
  • Hua Zhang,
  • Jinhua Wang,
  • Tao Luo,
  • Chunhua He

摘要

As an emerging pollutant widely present, antibiotics pose a potential threat to biological wastewater treatment. However, studies on the impact of mixed antibiotics on biologicalnitrogen removal are limited. Three norfloxacin (NOR)-oxytetracycline (OTC) ratios (R1-R3) were established using the direct equipartition ray method and uses high-throughput sequencing technology and PICRUSt2 to evaluate the impact of mixed antibiotics at different concentrations on nitrogen removal efficiency, microbial community structure, and metabolic functions. The results show that the inhibitory effect of mixed antibiotics on nitrogen removal efficiency increases with concentration. Low-concentration mixed antibiotics (≤ 10 mg/L) have a negligible impact on biological nitrogen removal performance, whereas high-concentration mixed antibiotics (≥ 10 mg/L) severely affect it. Specifically, compared with the blank group, in the high-concentration group, effluent NH4+-N increased from 0.91 mg/L to 23.58–29.34 mg/L, while COD increased from 27.75 mg/L to 277.38-307.31 mg/L. High-throughput sequencing showed that, as the concentration of mixed antibiotics increased, the relative abundance of key denitrifying bacteria (Thauera and Hydrogenophaga) significantly decreased. Co-occurrence network analysis indicates that antibiotic mixtures with similar concentrations promote the enrichment of core nitrogen cycling groups and induce new community defense mechanisms. PICRUSt2 functional prediction showed that mixed antibiotics primarily inhibited the synthesis of microbial ABC transporters, Amino acid biosynthesis and Two-component systems, collectively disrupting microbial protein synthesis and proliferation, thereby reducing nitrogen removal efficiency. This study clarifies the mechanistic effects of mixed antibiotics on microbial metabolic pathways and provides a theoretical basis for the risks of emerging pollutants in biological wastewater treatment.