Shifts of bacterial community and molecular ecological network at the presence of fluoroquinolones in a constructed wetland system

Fluoroquinolones (FQs) has caused increasing concerns regarding its potential environmental risks. However, their effects on bacterial community and microbial interactions in wetland system remains unclear. To verify these issues, a lab-scale constructed wetland exposed to low concentration FQs mixture was carried out for two months. The results showed that the removal efficiencies of COD and TP were negatively affected. FQs significantly increased the bacterial diversity and altered the overall bacterial community structure. Proteobacteria significantly decreased while Firmicutes exhibited opposite tendency (P < 0.05). Dechloromonas and Delftia, involved in phosphorus removal, decreased significantly (P < 0.05). Molecular ecological network analysis suggested that FQs promoted the network complexity and microbial interactions. A super module emerged at FQs and among-module connections were weakened obviously. Additionally, Nodes of Betaproteobacteria lost most interactions while Clostridia acquired more interactions at the presence of FQs. This study provided insights into how the bacterial community and their molecular ecological network respond to FQs in constructed wetland system.