Riverine floodplains as hotspots for the (co-)proliferation of antibiotic and metal resistance genes in the environment

• Applicants: Professorin E. Marie Muehe, Ph.D.; Dr. Anja Worrich
• Subject Area: Soil Sciences ; Microbial Ecology and Applied Microbiology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 535177170

Contaminants with antimicrobial properties, including heavy metals and antibiotics, pose a significant threat to soil health. While heavy metals are often considered a legacy contamination, antibiotics are emerging contaminants. Riverine floodplains, situated between heavy metal-transporting rivers and agricultural fields, are potential hotspots for the co-occurrence and proliferation of heavy metal resistance genes (HRGs) and antibiotic resistance genes (ARGs). This study aims to investigate the role of riverine floodplains as contact zones for the simultaneous emergence and movement of antibiotics and heavy metals, and associated resistant genes. We hypothesize that resistance genes to either contaminant will be spread in the presence of the other contaminant in riverine floodplains, as both resistances enter floodplains from different sources and occur on the same mobile genetic elements. Three research objectives are addressed: Determining the prevalence and distribution of HRGs and ARGs in riverine floodplains and their distribution along opposing antibiotic and heavy metal gradients. Elucidating the adaptation of floodplain grasslands to co-contamination with heavy metals and antibiotics and assessing the movement of resistance genes. Assessing the impact of the rhizosphere on the proliferation of ARGs and HRGs under exposure to either contaminant. The proposed research project will involve field site assessments, measuring heavy metal and antibiotic concentrations, and quantifying the corresponding resistance genes. Additional factors influencing resistance gene spread will be investigated, including soil geochemistry, biotope type, climate, and microbial community dynamics. A model floodplain strip experiment will be conducted to assess resistance gene movement and degradation. The adaptation of microbial communities will be analyzed using amplicon sequencing, and the role of rhizosphere processes in resistance gene proliferation will be evaluated. The findings of this study will contribute to a better understanding of the factors influencing the co-occurrence and proliferation of ARGs and HRGs in riverine floodplains.

• DFG Programme: Research Grants