Microbiome and mobile antibiotic resistome in Australian wastewater treatment plants and recycled wastewater products
Speaker: Dr Barbara Drigo
Understanding the dynamics of antibiotic resistant microorganisms in the urban water cycle is an increasingly important goal as antibiotic resistance is recognized one of the greatest human health challenges of the 21st century. Municipal urban wastewater plants are suspected to be an “evolutionary hotspots” for the propagation of antibiotic resistant bacteria and their genes (ARB&Gs) to the environment and consequently to human. The mechanisms underlying this phenomenon are still unclear, but it is likely that the concomitant presence of antibiotics and other pollutants in urban wastewater could trigger the co-selection and horizontal gene transfer of resistance genes. Here, we monitor the ARB&Gs of the three largest municipal wastewater treatment plants in South Australia. ARB&Gs monitoring focused not only on influents, effluents, recycled water and biosolids products, but also on the intermediate treatment stages. To assess the abundance and expression profile of ARB&Gs we used a suite of high throughout put molecular tools, including sequencing and digital droplet PCR. Results demonstrate the efficacy of physical treatment stages such as ultra-filtration for removing ARB&Gs from the water stream, but also reveal the subsequent concentration of ARB&Gs into the sludge fraction and biosolids. The post-production biosolids ageing process was found to significantly decrease but not eradicate the ARB&Gs load prior to land application. Recycled water entering the reuse pipelines was of demonstrably high quality with IntI-1, blaTEM, vanA, qnrS, sul1 and ctx-m 32 all below detection by standard qPCR analysis, however digital droplet PCR analysis was sensitive enough to detect residual ARB&Gs and to follow their regrowth potential. Our findings provided a baseline understanding of the prevalence of antibiotic resistance in wastewater influents, effluents and biosolids. The efficacy of urban wastewater treatments on the survival and regrowth of ARB&Gs is used to model and predict the fate of antibiotic resistance in complex environments.
Dr Barbara Drigo conducted her doctoral studies at the Netherlands Institute of Ecology (NIOO-KNAW) in the Netherlands and was awarded her PhD in 2009 at the University of Leiden (the Netherlands). Her PhD research used a number of interrelated methods in molecular microbial ecology to study the effects of climatic conditions on plant-soil-microbial interactions. She then became research fellow at Wageningen University (the Netherlands), where she studied the correlation between disease suppressiveness and bio-control agents in agricultural ecosystems. Shortly after, she moved to the Hawkesbury Institute for the Environment at Western Sydney University, where she developed novel experimental systems to test microbial dynamics and functioning in response to environmental change in natural ecosystems. In August 2016 she commenced a new research role with the Future Industries Institute (FII) at the University of South Australia. At FII she is currently studying the survival and regrowth/transfer of antibiotic resistant microorganisms and genes in terrestrial ecosystems.