Are emerging contaminants affecting drinking water microbial biofilms?

The presence of biofilms in drinking water (DW) distribution systems is unavoidable as well as the presence of trace levels of different emerging contaminants (ECs). ECs constitute a potential risk for the “One Health” trilogy. In particular, the presence of antibiotics in the environment has been associated with antibiotic-resistance spread worldwide. However, the information about the pressure caused by non-antibiotic and non-pharmaceutical ECs remains scarce. This study aims to highlight the possible impact of different pharmaceutical and even some non-pharmaceutical ECs on the behavior of bacteria isolated from DW. Few recent works reported the impact of a continuous exposure to specific ECs on DW microbiota; however, this topic still remains unexplored by the scientific community. In order to provide more realistic knowledge about the continuous exposure of DW biofilms to ECs, Acinetobacter calcoaceticus isolated from DW, was used to form biofilms. These biofilms were exposed to several pharmaceutical (ibuprofen, ciprofloxacin, carbamazepine) and non-pharmaceutical (caffeine) ECs. The results demonstrated that the presence of these ECs may affect DW bacteria behavior, namely the ability to form biofilms and the tolerance to antibiotics. Additionally, this work demonstrates the possible impact of ECs on DW bacteria behavior and highlights that the impact of ECs on DW microbial community is dependent on the bacterial diversity, environmental conditions and also the time of exposure.