Effects of antibiotics and heavy metals on denitrification in shallow eutrophic lakes. (March 2022) - Deng, Fei
Abstract: Antibiotic and heavy metal residues in shallow lakes caused by aquaculture and human activities such as sewage discharge have attracted much attention and public concern. However, mechanisms by which these environmental pollutants affect the microorganism-mediated biogeochemical cycle are unknown. This study focused on the effects of antibiotics, heavy metal, and antibiotic resistance genes (ARGs) on denitrification in shallow lakes. The results showed that antibiotics and metal elements had inhibitory effects on denitrification, whereas AGRs exhibited stimulating effects. Specifically, the enrofloxacin concentration showed a significant negative correlation with the copy number of denitrifying bacteria, whereas the copy number of the ARGs sulI, sulII, and tetG showed significant positive correlations. In addition, tetG was closely related to the community structure of nir S-type denitrifiers, and nir S-type denitrifiers were significantly correlated with the potential denitrification rate (PDR). Furthermore, the ARGs sulI, sulII, and tetG were positively correlated with PDR ( P < 0.05). By contrast, the metal elements arsenic, manganese, cobalt, and antimony were negatively correlated with the copy number of denitrifying bacteria. Arsenic was significantly correlated with the community composition of nir K-type denitrifiers, but nir K-type denitrifiers did not show a significant correlation with the PDR. This work extends our understanding of the effects of antibiotics and heavy metals on denitrification, but further studies are needed to determine the interaction effects of pollutants. Graphical abstract: Image 1 Highlights: Antibiotics and heavy metals had a negative effect on denitrification but antibiotic resistance genes had a positive effect. tetG and trophic status had significant positive effect on denitrification while SMX and As showed negative effect. tetG was closely related to the nir S-type denitrifiers and As was closely related to the nir K-type denitrifiers.