Variation in bacterial community structure of aerobic granular and suspended activated sludge in the presence of the antibiotic sulfamethoxazole.

•Granular and conventional activated sludge were exposed to 2 μg/L antibiotic SMX.•2 μg/L SMX did not affect treatment performance of suspended and granular sludge.•2 µg/L SMX altered bacterial community composition of both sludge types in 2 months.•Nitrosomonas, Pseudomonas, and Acinetobacter were SMX-degrading genes in sludge.•Rhodocyclaceae, Zoogloea, Shewanella, and Aeromonas were found resistance to SMX.