Profiles of antibiotic resistance genes (ARGs) and virulence genes (VGs) and their temporal interactions in OD and MBR

Antibiotic resistance genes (ARGs) and virulence genes (VGs) associated with bacterial pathogens are of great concern in WWTPs, while current knowledge of their profiles and co-occurrence patterns in different time intervals is barely sufficient. Moreover, the impacts of treatment process on ARG/VGs diversity also remain clear. To this end, this study was launched to address the differences of the ARG/VGs diversity between an oxidation ditch (OD) and an membrane bioreactor (MBR) and the co-occurrence patterns in different time intervals using a functional gene array-GeoChip. Two full-scale wastewater treatment systems applying the processes of oxidation ditch (OD) and membrane bioreactor (MBR) were investigated. They treated identical wastewater at the same scale and ran parallelly. A total of 48 samples were collected, 24 out of which were taken in the short term and the remaining 24 samples were taken in the long term. In each time interval, 12 mixed-liquor suspended sludge (MLSS) samples were collected daily or weekly on 12 consecutive days/weeks from each system and the extracted DNA were analyzed by functiional gene-based GeoChip.