The contamination of natural ecosystems, food and water resources by pesticides is matter of concern for the scientific community, policy and industry stakeholders, collectivities, and the society in general. Within this context, streams and rivers have the capacity to collect inputs from the watershed (including pesticides) and re-distribute them towards human activities and adjacent ecosystems, supplying important ecosystem services such as self-depuration of surface waters. At present, the herbicide glyphosate (also known by its tradename Roundup) is at the head of the list of the most frequently detected pesticides in surface waters from Europe. In France, the aminomethylphosphonic acid (AMPA), which is the primary degradation product of glyphosate, is the most often detected molecule (60% detection frequency at concentrations ranging 0.1-48 µg/L) and the second is the glyphosate itself (30-40% detection frequency, 0.2-165 µg/L). This wide detection of glyphosate and AMPA in rivers, especially at their most downstream sections, suggest weak biodegradation capacities by riverine microbial communities which are often subjected to multi-stress factors influencing their activity, structure, and diversity. The BIGLY project aims to investigate the capacity of riverine biofilms to degrade the herbicide glyphosate. While few research programs have assessed the capacity of natural biofilms in removing pesticides from waters, several laboratory studies have already identified microbial strains capable to degrade glyphosate through the AMPA and sarcosine degradation pathways. Knowing that glyphosate utilization by bacteria and cyanobacteria is mostly associated to the acquisition of inorganic phosphorus, phosphorus eutrophication gradients in rivers might compromise biofilm self-depuration capacities for glyphosate. The BIGLY project proposes an interdisciplinary, multi-scale, and multi-organism approach permitting to address both fundamental and applied research questions on glyphosate degradation by riverine biofilms:
- Is there a link between rivers eutrophication and biofilm potential to decompose glyphosate?
- Which are the microorganisms and enzymes involved in glyphosate degradation in biofilms?
- Can heterotrophy and global warming enhance glyphosate degradation by biofilms?
Results from the BIGLY project will allow determining glyphosate contamination thresholds and self-depuration capacities of biofilms that will certainly contribute to improve glyphosate remediation procedures (species and enzymes involved) and management of agricultural and urban watersheds. This project will permit also to better comprehend the ecology of riverine biofilms in pesticide-contaminated systems and predict their evolutions (in terms of structure, biodiversity, and activity) in a context of global change: rivers channelization, eutrophication, and global warming. Finally, the main outcomes of this research program will be disseminated to academic, policy and industry stakeholders using targeted communication tools, and contribute to the training of highly qualified personnel.