PhD in environmental sciences (Chemistry and Microbiology) – Study of the cocktail effects on the fate, toxicity and bioremediation of pesticides

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PhD in environmental sciences (Chemistry and Microbiology) – Study of the cocktail effects on the fate, toxicity and bioremediation of pesticides

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Job description

Offer DescriptionThe evolution of agronomic practices in conventional agriculture has led to repeated spreading of formulated pesticide active ingredient mixtures, each being applied at low dosage, in order to protect crops more effectively. The result is a multi-residue contamination of soils but also of water (highly monitored environmental compartments), with mixtures of parent molecules and their various degradation products. For example, a recent study showed that mixtures of 2 or more pesticides were detected in 60% of the 300 European agricultural soils sampled (Silva et al., 2019) and this presence of pesticide mixtures seems to be the norm rather than the exception (Chiaia-Hernandez et al., 2017; Riedo et al., 2021). Moreover, the spreading of farm effluents (manure) or sludge to amend agricultural soils is a common practice but these amendments contain increasing quantities of pharmaceutical molecules, heavy metals and other contaminants. The impact of this multi-residue contamination (cocktail effects) on the fate of the individual molecule is not often considered in the literature (Schaeffer et Wijntjes, 2022; Smith et al., 2024). Nevertheless, this should allow us to investigate cumulative, synergic or antagonist effects and therefore to have a better assessment of the overall real impact on ecosystems, in particular on their degrading capacity of various contaminants present (synergy or inhibition), toxicity and global risk assessment.The aim of this research work is therefore to study the impact of various mixtures of molecules (pure or formulated pesticides, pharmaceuticals, parent molecules and/or degradation products, heavy metals) on the biodegradation and toxicity (microbial growth, Microtox®…) of each molecule individually, in particular pesticides. These studies will be carried out in liquid media to start with. For this, (1) microbial strains able to degrade the target molecules will be isolated by enrichment cultures from various environmental matrices receiving these contaminants. The metabolites formed will be identified by various analytical techniques (e.g. LC-MS, NMR) in order to establish the biodegradative pathways; (2) the impact of the mixture of pure or formulated molecules on the biodegradation of each one (modulation of kinetics, metabolic pathway) will be studied; (3) this impact will also be assessed from a toxicity point of view, by using a standardized method (Microtox®), monitoring the growth of different microbial strains and comparing it for addition of either single molecules or a mixture.In a second part of the thesis, the isolated strain(s)/consortia will be used to develop a preventive bioremediation process in soil microcosms under controlled climatic laboratory conditions (Carles et al., 2021) or in outside natural conditions. The evolution of each strain we supply initially, as well as their biodegradative activities, will be monitored. Chemical monitoring of the parent molecules and their metabolites will also be carried out, using the analytical protocols developed in the first part of the thesis.References : Carles et al. (2021) J Hazard Mater. 416:125740. doi: 10.1016/j.jhazmat.2021.125740 ; Chiaia-Hernandez AC et al. (2017) Environ Sci Technol. 51(18):10642. doi: 10.1021/acs.est.7b02529 ; Riedo et al. (2021) Environ Sci Technol. 55(5):2919-2928. doi: 10.1021/acs.est.0c06405 ; Schaeffer & Wijntjes (2022) Eco-Env. Health 1:23-30. doi : 10.1016/j.eehl.2022.02.002 ; Silva et al. (2019) Sci Total Environ. 653:1532-1545. doi: 10.1016/j.scitotenv.2018.10.441 ; Smith et al. (2024) Nat Microbiol. doi: 10.1038/s41564-024-01626-9.ContextThe research work will be carried out between the team « Biocatalysis and Metabolism » (BioMETA) from the Chemistry Institute of Clermont-Ferrand (ICCF, UMR CNRS 6296) and the team « Microbial communities : Ecotoxicology-Health» (CMES) from the Laboratory Microorganisms : Genome and Environment (LMGE, UMR CNRS 6023). Both these laboratories are located nearby on the same campus.Both supervisors of this thesis (Pascale Besse-Hoggan, Senior Researcher CNRS, ICCF and Isabelle Batisson, Professor, LMGE) have been working together for more than 20 years and have complementary expertises in the field of organic contaminant biodegradation (in particular pesticides). They develop combined chemical and biological approaches to understand the fate of these contaminants in water and soil, getting from degrading-microbial strain isolation to metabolic pathways. In the last years, they have developed innovative bioremedation processes.RequirementsResearch Field Chemistry » Analytical chemistry Education Level Master Degree or equivalentSkills/QualificationsThe candidate should have a Master’s degree or equivalent in environmental or analytical chemistry, or possibly ecotoxicology. The PhD topic proposed is clearly on the boundaries of chemistry with microbiology, therefore, several skill-sets are required to take on this project.i) solid theoretical and practical competence in analytical chemistry (HPLC, NMR and LC-MS, particularly).ii) Basic knowledge or competence in pasteur microbiologyiii) a very pronounced aptitude for organisation, rigour, open-mindedness and aptitude for team work.We are looking for a candidate to get involved in cross-disciplinary research, with a marked taste for experimental analysis, an enthusiastic, rigorous, methodical and autonomous person, who enjoys working and communicating with different research teams. The candidate should be able to write up results and other documents in French and/or English.Languages FRENCH Level GoodLanguages ENGLISH Level GoodResearch Field Chemistry » Analytical chemistryBiological sciences » BiologyAdditional InformationAdditional commentsStarting date: 01/10/2024Application: Interested candidates should submit a curriculum vitae, a covering letter outlining research interests and relevant experience in the domain, copies of academic transcripts and degrees and at least one academic reference by 16/05/2024 to the thesis supervisors : Pascale Besse-Hoggan ( ) and Isabelle Batisson ( ).Work Location(s)Number of offers available 1 Company/Institute Institute of Chemistry of Clermont-Ferrand and Laboratory Microorganisms: genome and Environment Country France City Aubiere Cedex Postal Code 63178 Street 24 Avenue Blaise PascalWhere to apply E-mailpascale.besse@uca.frContact Cityclermont-ferrand WebsiteStreet24 avenue Blaise Pascal Postal Code63178 E-MailPascale.Besse@uca.frSTATUS: EXPIRED

Expected salary

Location

Aubière, Puy-de-Dôme

Job date

Wed, 10 Apr 2024 23:48:20 GMT

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