The fate of tetracycline in vegetated mesocosmic wetlands and its impact on the water quality and epiphytic microbes

Abstract

The fate of antibiotics and their impact on antibiotic resistance genes (ARGs) and microbial communities are far from clear in wetlands. The fate and impact of tetracycline (TC) on the nutrient degradation of wetlands and epiphytic microbes were investigated. This study showed that after TC spiking, 99.7% of TC were removed from the surface water of wetlands containing Vallisneria spiralis within 4 days post-treatment. TC spiking impaired the nutrient removal capacity and disrupted epiphytic microbial community structure while enhancing the abundance of 11 ARGs subtypes, including tetracycline resistance genes, tetX, tetM, tetO, tetQ, tetS, and tet36. TC decreased bacterial biodiversity but amplified the relative abundance of Proteobacteria and Firmicutes by 4% and 61%, respectively, and increased eukaryotic diversity. 16 metabolic pathways including Carbohydrate, Energy, Amino acid, ‘cofactor and vitamins’ metabolisms were significantly (p < 0.01) increased in TC treatment. Phylogenetic, functional prediction analysis indicated that Flavobacterium was positively related with xenobiotics, cell motility, ‘terpenoids and polyketides’ metabolism but negatively related to nucleotide metabolism, while Rhodobacter showed a reverse trend but positively related with nucleotide and ‘glycan biosynthesis’ and metabolism. These data highlighted that TC has negative impacts on epiphytic microbial community and nutrients removal in wetlands.