Investigating antibiotics, antibiotic resistance genes, and microbial contaminants in groundwater in relation to the proximity of urban areas. (May 2018)

• Record Type: Journal Article
• Authors: Szekeres, Edina; Chiriac, Cecilia Maria; Baricz, Andreea; Szőke-Nagy, Tiberiu; Lung, Ildiko; Soran, Maria-Loredana; Rudi, Knut; Dragos, Nicolae; Coman, Cristian
• Is Part Of: Environmental pollution. Volume 236(2018)
• Page Start: 734
• Page End: 744
• Publication Date: 2018-05
• Subjects: Groundwater quality -- Antibiotic residues -- Antibiotic resistance -- Microbial contaminants -- Health risk; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2018.01.107
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Groundwater is an essential public and drinking water supply and its protection is a goal for global policies. Here, we investigated the presence and prevalence of antibiotic residues, antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and microbial contamination in groundwater environments at various distances from urban areas. Antibiotic concentrations ranged from below detection limit to 917 ng/L, being trimethoprim, macrolide, and sulfonamide the most abundant antibiotic classes. A total of eleven ARGs (aminoglycoside, β-lactam, chloramphenicol, Macrolide-Lincosamide-Streptogramin B - MLSB, sulfonamide, and tetracycline), one antiseptic resistance gene, and two MGEs were detected by qPCR with relative abundances ranging from 6.61 × 10 −7 to 2.30 × 10 −1 copies/16S rRNA gene copies. ARGs and MGEs were widespread in the investigated groundwater environments, with increased abundances not only in urban, but also in remote areas. Distinct bacterial community profiles were observed, with a higher prevalence of Betaproteobacteria and Bacteroidetes in the less-impacted areas, and that of Firmicutes in the contaminated groundwater. The combined characteristics of increased species diversity, distinct phylogenetic composition, and the possible presence of fecal and/or pathogenic bacteria could indicate different types of contamination. Significant correlations between ARGs, MGEs and specific taxa within the groundwater bacterial community were identified, revealing the potential hosts of resistance types. Although no universal marker gene could be determined, a co-selection of int 1, qac EΔ1 and sul I genes, a proxy group for anthropogenic pollution, with the tet C, tet O, tet W resistance genes was identified. As the tet group was observed to follow the pattern of environmental contamination for the groundwater samples investigated in this study, our results strongly support the proposal of this group of genes as an environmental tracer of human impact. Overall, the present study investigated several emerging contaminants in groundwater habitats that may be included in monitoring programs to enable further regulatory and protection measures. Graphical abstract: Image 1 Highlights: Antibiotics, ARGs and MGEs are widespread in groundwater ecosystems, not only in urban, but also in remote areas. Trimethoprim, macrolide, and sulfonamide were the most abundant antibiotic classes. Increased species diversity, distinct microbial diversity, and bacterial pathogens characterized the impacted groundwater. Significant correlations between ARGs, MGEs and groundwater bacterial community were identified. The group of class 1 integron, related ARGs and tetC, tetO, tetW resistance genes can be used as indicator of pollution. Abstract : Pollutants of emerging concern are widespread in groundwater regardless of the proximity to urban areas, with significant correlations between ARGs, MGEs and groundwater bacterial community.