Evolution of microbial community and antibiotic resistance genes in anammox process stressed by oxytetracycline and copper.

The individual and combined impacts of copper ion (Cu ²⁺ ) and oxytetracycline (OTC) on anaerobic ammonium oxidation (anammox) performance and its self-recovery process were examined. Experimental results showed that the anammox performance and activity of anammox bacteria were inhibited by 1.0 mg L ^-1 OTC, Cu ²⁺ and OTC + Cu ²⁺ , and both single and combined inhibitions were reversible. The abundance of functional genes and parts of antibiotic resistance genes (ARGs) were positively related to the dominant bacterium Ca. Kuenenia, implying that the recovery of the performance was associated with the progressive induction of potentially resistant species after inhibition. The above outcomes illustrated that anammox bacteria were stressed by metals and antibiotics, but they still could remove nitrogen at a rate higher than 20.6 ± 0.8 kg N m ^-3 d ^-1 , providing guidance for engineering applications of anammox processes.
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