Drinking water biofiltration: Behaviour of antibiotic resistance genes and the association with bacterial community

Abstract

Antibiotic resistance genes (ARGs) are being detected in drinking water frequently, constituting a major public health issue. As a typical drinking water treatment process, the biofilter may harbour various ARGs due to the filter biofilms established during the filtration process. The objective of this study was to investigate the behaviour of ARGs (blaCTX-M, blaOXA-1, blaTEM, ermB, tetA, tetG, tetQ, tetW, tetX, sul 1, sul 2, dfrA1 and dfrA12) and their possible association with bacteria in a bench-scale biofiltration system. The impact of filter media on horizontal gene transfer (HGT) was also explored using a model conjugative plasmid, RP1.The biofiltration system comprised four types of biofilters, including sand, granular activated carbon (GAC), GAC sandwich, and anthracite-sand biofilters. Results showed that although the absolute abundance of ARGs decreased (0.97-log reduction on average), the ARGs' abundance normalised to bacterial numbers showed an increasing trend in the filtered water.Biofilms collected from the surface layer revealed the lowest relative abundance of ARGs (p < 0.01) compared to the deeper layer biofilms, indicating that the proportion of ARG-carrying bacteria was greater in the lower position. Most chosen ARG numbers correlated to Proteobacteria, Acidobacteria and Nitrospirae phyla, which accounted for 51.9%, 5.2% and 2.0% of the biofilm communities, respectively. GAC media revealed the highest transfer frequency (2.60 × 10 -5 ), followed by anthracite (5.31 × 10 -6 ) and sand (2.47 × 10 -6 ).Backwashing can reduce the transferability of RP1 plasmid significantly in biofilms but introduces more transconjugants into the planktonic phase. Overall, the results of this study could enhance our understanding of the prevalence of ARGs in drinking water biofiltration treatment.

Interfacial Charge Transfer between Silver Phosphate and W2N3 Induced by Nitrogen Vacancies Enhances Removal of β‐Lactam Antibiotics

“…[4,5] The presence of antibiotics in environment, particularly in wastewater and drinking water, even at low concentrations, can lead to the emergence of resistant bacteria problem threatening human health. [6][7][8][9] The β-lactam antibiotics are the most frequently used antibiotics, accounting for more than 50% of the total worldwide antibiotic consumption. [10] In addition, penicillin G (PNL) and amoxicillin (AMX) are among the most commonly used β-lactam antibiotics, which are also the most vulnerable to leakage into the environment.…”

Characteristics of Antibiotic Resistance Genes and Antibiotic-Resistant Bacteria in Full-Scale Drinking Water Treatment System Using Metagenomics and Culturing

“…Some previous studies have demonstrated that the bacterial community is strongly correlated with the resistance profile ( Jia et al, 2015 ; Zhang L. et al, 2018 ; Chen et al, 2019 ). In particular, Proteobacteria and Acidobacteria are important hosts of ARGs ( Ma et al, 2019 ), and some studies have detected significant positive correlations between them and ARGs ( Su et al, 2015 ; Xu et al, 2020 ). Thus, the changes in the relative abundance of Proteobacteria and Acidobacteria might explain the variations in the abundances of ARGs during the water treatment processes.…”

Metagenomic analysis of microbial community structure and function in a improved biofilter with odorous gases

“…For many bio ltration systems, Proteobacteria was the most abundant phylum during the treatment process. For examples, Proteobacteria occupies 58-92% share in two butyric acid bio ltration systems [17], 3.55-51.03% share in a series of laboratory-scale land ll reactors [35], and 51.9% share in a drinking water bio ltration [36]. Addition to Proteobacteria, Planctomycetes and Chloro exi also were reported to be the dominant phyla in various bio lter reactors [37,38].…”