Response of denitrifying community, denitrification genes and antibiotic resistance genes to oxytetracycline stress in polycaprolactone supported solid-phase denitrification reactor.

•Complete nitrate reduction in solid phase denitrification with 0–1 mg L−1 OTC.•Efficient nitrate reduction still achieved after domestication with 5 mg L−1 OTC.•OTC stress mainly promoted tetracycline resistance genes abundances.•125 types of denitrifying genera contained otrA favorable for resisting OTC stress.•Denitrification genes NAR, NIR and NOR significantly declined as OTC ≥ 0.25 mg L−1.