Dr Pau de Yebra Rodó conducted research into antibiotic resistance in lakes, wastewater and livestock farming as part of the research alliance Leibniz INFECTIONS. In October 2026, he successfully defended his doctoral thesis at the Faculty of Mathematics and Natural Sciences at the University of Potsdam. The thesis demonstrates how water bodies, sewage treatment plants and pig farming can contribute to the spread of antibiotic resistance genes. The findings underscore the importance of an integrated One Health approach, which considers the health of humans, animals and the environment as a whole.
In his doctoral thesis, Dr Pau de Yebra Rodó investigated the occurrence and diversity of antibiotic resistance genes in various ecosystems in the Berlin-Brandenburg region, as well as in wastewater and pig farms. For this, he used metagenomic methods, which enables the analysis of genetic material of microbial communities. “This broad methodological approach allows us to identify, within the prokaryotic genomes present in the samples, those genes responsible for antibiotic resistance,” explains Dr de Yebra Rodó
The investigations showed that urban water bodies, lake sediments and wastewater contained a greater diversity of antibiotic resistance genes than rural water bodies. Lake sediments can act as long-term reservoirs and retain genetic traces of previous exposure to antibiotics. Even though the wastewater treatment process managed to reduce the burden of antibiotic resistance genes, up 144 genes could still be detected in both the influent and the treated wastewater. Treated wastewater therefore remains a potential source of resistance genes entering the environment.
Antibiotic resistance genes remain in the treated effluent even after waste water treatment
A further study examined the impact of the 2022 Oktoberfest on wastewater in Munich. Once the major event began, the diversity trend of antibiotic resistance genes in the influent increased. At the same time, the sewage treatment plant altered the composition of the microorganisms: some potentially pathogenic species declined, whilst certain environmental bacteria increased in the effluent. In a further study, the scientist examined antibiotic resistance genes in fecal samples from piglets over a five-week period. The result: antibiotic resistance gene signatures from antibiotics present in the pig farms could be detected, e.g. tetracycline, elfamycin or fusidane. In addition the overall diversity of antibiotic resistance genes was as rich as the one detected in the wastewater treatment plant.
Taken together, the PhD study illustrates that antibiotic resistance genes occur in different habitats and may be interconnected via processes such as slurry application, water runoff and groundwater exchange. “Antibiotic resistance must be investigated across the boundaries of individual habitats. Only by considering humans, animals and the environment together can we better understand potential pathways of spread and develop targeted measures.” emphasises de Yebra Rodó. “Furthermore, lower economic wealth facilitates the persistence and spread of antimicrobial resistance by combining overcrowding and poor sanitation with limited healthcare access, weak diagnostics, and unregulated antibiotic use, thereby promoting inappropriate antibiotic use, infection risk and the circulation of resistant pathogens.”
The thesis, entitled “Aquatic Ecosystems and Livestock as Habitats and Vectors of Antimicrobial Resistance (AMR): A One Health Metagenomic Study’ was carried out in the Department of Wildlife Diseases at the Leibniz Institute for Zoo and Wildlife Research, led by Prof. Alex Greenwood, and in the Aquatic Microbial Ecology Research Group at the Leibniz Institute of Freshwater Ecology and Inland Fisheries, led by Prof. Hans-Peter Grossart.
A paper resulting from the research project was published in 2026 in the journal iScience.
Source
De Yebra P, Zoccarato L, Galdindo JA, Numberger D, Abdulkadir N, Grossart HP, Greenwood AD: Diversity of antibiotic resistance genes increases in urbanized lakes: a multi-tool screening. iScience, 2026; 29. https://doi.org/10.1016/j.isci.2026.115892