MEMENTO

Bio-pesticides are increasingly used to face growing societal and economic concern about human and environmental risk associated to synthetic pesticides. Nevertheless, recent studies have highlighted that they can adversely affect non-target organisms. This is of particular concern regarding the urgent need to replace synthetic fungicides detected ubiquitously in the environment by natural ones. This can lead to no-sense decisions such as the large use of copper in bio-vineyards whereas its wide spectrum ecotoxicity has been described since a long time. Thus, there is a crucial need to evaluate the potential impact of these (bio)fungicides on natural ecosystems compared to synthetic ones. In this context, MEMENTO aims to characterize and compare the response and the tolerance of aquatic ecosystems to biofungicides vs synthetic ones. To address this scientific challenge, MEMENTO proposes a paradigm shift in ecotoxicology through the implementation of a high-resolution mass spectrometry-based untargeted metabolomics approach on aquatic biofilms allowing to provide a full picture of the molecular responses at the whole microbial community level. Indeed, these communities are a model of particular relevance regarding their taxonomic diversity (all kingdoms are represented) and their key role in ecosystem functioning and sustainability of associated services. Also, the untargeted metabolomics approach is a cutting edge method of choice because of its capacity to simultaneously assess exposure and associated responses, as well as to characterize the signalling pathways involved in these responses, and providing insight about microbial chemical interactions. In the adverse outcome pathway conceptual framework, this innovative approach will be combined to the assessment of structural/physiological/functional descriptors and of tolerance on the biofilms (periphyton and leaf litter) and their components (mono/co-culture) in order to link the exposure, the molecular, functional, structural response and the acquisition of tolerance at the microbial community level (i.e. tolerance outcome pathway). Thus, MEMENTO methodology is organized along an increasing degree of complexity in terms of experiments (from testing single chemical effects to the investigation of confounding factors) and in terms of endpoints and benthic substrata (from the molecular to the physiological/functional and structural responses, from the population to the community responses). Altogether these investigations will unravel step by step the mechanisms of tolerance acquisition to biofungicides vs synthetic ones as single chemicals and mixtures, and evaluate the influence of environmental factors (temperature, photoperiod, environmental mixture) on its tolerance. Overall, MEMENTO will improve scientific knowledge about: (i) the identity of molecular (metabolic) pathways and associated metabolites in the response, the acquisition of tolerance and the tolerance itself in aquatic microbial communities and ecosystems to bio vs synthetic fungicides (e.g. copper vs. azole); (ii) the link between the exposure and the molecular/physiological /functional/structural responses in aquatic biofilms and some of its components (fungi, diatoms, cyanobacteria); (iii) the influence of environmental factors in the response and acquisition of tolerance to aquatic microbial communities to bio vs synthetic fungicides; (iv) the co-tolerance associated to these compounds and environmental factors. By doing so, this project will support the better understanding of the mechanisms of tolerance acquisition in microbial communities and the consequences on ecosystems but also the identification of specific and sensitive molecular descriptors (i.e. metabolites or metabolite fingerprints) as candidate biomarkers able to early detect the tolerance/impact at the community level and the preservation/alteration of their functioning and associated ecosystem services.