How do metal pollutant concentration and speciation affect wastewater microbial diversity and antibiotic resistance?

Doelsch Emmanuel, Brunetti Gianluca, Vasileiadis Sotirios, Drigo Barbara, Aleer Samuel, Lombi Enzo, Donner Erica. 2019. How do metal pollutant concentration and speciation affect wastewater microbial diversity and antibiotic resistance?. In : Abstract book of the 5th International Symposium on the Environmental Dimension of Antibiotic Resistance (EDAR5). Hong Kong : University of Hong Kong, 1 p. International Symposium on the Environmental Dimension of Antibiotic Resistance. 5, Hong Kong, Hong Kong, 9 Juin 2019/14 Juin 2019.

Résumé : In this study we compared metal-induced cross-resistance to antibiotics in urban wastewater, whilst paying particular attention to issues of metal speciation. Municipal wastewater influent was used to establish microcosms spiked with silver (Ag), copper (Cu), or zinc (Zn) at concentrations from 1-10000 μM. All treatments were sampled for analysis after 1 and 7 day's incubation. X-ray absorption spectroscopy (a powerful, synchrotron-based structural technique) was used to directly investigate Ag, Cu, and Zn speciation. Diffusive Gradients in Thin Film (DGT), filtration, and acid digestion based methods were used to further interrogate metal chemistry and solubility. Partial 16S rRNA amplicon sequencing was used to assess bacterial diversity, and real-time PCR to measure relative abundance of marker genes for metal (Ag, Cu, Zn) resistance, antibiotic-resistance, and horizontal-gene-transfer (HGT), and to confirm interesting trends indicated by the sequencing data. Multivariate statistical analysis of bacterial community responses to Ag, Cu and Zn showed that exposure time, metal concentration gradient, and metal speciation were all significant factors associated with measured changes. Ag/Cu/Zn sulfides comprised a significant proportion of the metal speciation profiles at low-medium range concentrations, whereas Ag-chloride, metal-phosphate and organic bound species were more important at higher concentrations. Maximum likelihood phylogenies of dominant OTUs indicated strong metal induced selection of potential human pathogens (e.g. Acinetobacter spp., Arcobacter spp.); this was confirmed by targeted qPCR (e.g. for A. baumanii, A. butzlerii). These results demonstrate that wastewater metal pollutants induce significant increases in microbial resistance and HGT potential. Importantly, metal speciation is frequently overlooked in studies investigating metal-induced microbial effects but can significantly affect microbial community selection and function.

Auteurs et affiliations

• Doelsch Emmanuel, CIRAD-PERSYST-UPR Recyclage et risque (AUS) ORCID: 0000-0002-7478-4296
• Brunetti Gianluca, University of South Australia (AUS)
• Vasileiadis Sotirios, University of South Australia (AUS)
• Drigo Barbara, University of South Australia (AUS)
• Aleer Samuel, University of South Australia (AUS)
• Lombi Enzo, University of South Australia (AUS)
• Donner Erica, University of South Australia (AUS)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/594666/)

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