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

The treatment performance and bacterial community structure of conventional activated sludge and aerobic granules exposed to antibiotic sulfamethoxazole (SMX) was studied. For three months, two sets of sequencing batch reactors inoculated with conventional and granular biomass were fed with a synthetic municipal wastewater containing 2 μg/L SMX. The presence of SMX had no significant impacts on treatment performance of the reactors as well as stability of the granules. Results confirmed different bacterial community structure of flocs and granules. During the operation, variations in bacterial community structure of suspended and granular sludge were observed in all reactors. The variations in bacterial community composition due to the exposure to 2 μg/L SMX were found after two months in both suspended and granular biomass. Nitrosomonas, Pseudomonas, and Acinetobacter were detected as the genes capable of degrading SMX in both biomass types. Also, Rikenellaceae, Oscillospira, Rhodocyclaceae, Zoogloea, and Shewanella varied in abundance over the operation time. Rikenellaceae and Oscillospira were vulnerable to SMX and decreased in abundance the operation time; while Rhodocyclaceae, Zoogloea, Shewanella, and Aeromonas were found as SMX resistance genes.