Bacterial communities, metabolic functions and resistance genes to antibiotics and metals in two saline seafood wastewater treatment systems

This study investigated the bacterial communities, metabolic functions, antibiotic resistance genes (ARGs) and metal resistance genes (MRGs) in two alternating anaerobic/aerobic biological filters (A/O-BFs) treating saline seafood wastewater (SSW). Firmicutes was the most abundant phylum in both systems, and halophilic and alkaliphilic bacteria were largely enriched. 15 potential pathogens were obtained. Metabolism was the predominant bacterial function. 49 ARGs and 7 MRGs were detected, and the total abundance of ARGs increased while that of MRGs decreased. Clear shifts in bacterial structure and function, ARGs and MRGs were observed in both systems and at different heights. Co-occurrence of ARGs and MRGs and their hosts were identified. ARGs and MRGs mainly negatively correlated with bacterial functions, which were also the important contributors to shifts in bacterial communities and functions. This study highlights the importance of investigating ARGs and MRGs in SSW treatment systems and their complex interactions with bacterial communities and functions.