Poster De Conférence Année : 2023

Stable-Isotope Probing unravels fate of phenanthrene in poplar-microbes holobiont and identifies active soil and root endophyte degraders

Résumé

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants mainly found in anthropized soils where they can cause environmental and health issues on a global scale. Phytoremediation could be a cost-effective and reliable method for soil PAH decontamination. Studies on the dynamic of PAH dissipation in soil-plant systems have mostly focused on rhizospheric microorganisms. However, it has recently been shown that some of the PAHs in contaminated soils could be taken up and transported into plant tissues. Endophytes could have a key role in the fate of internalized PAHs and mitigate the plant response to PAH toxicity. DNA-Stable isotope probing (SIP) was developed two decades ago helping us with a fundamental question in microbial ecology “who is doing what?”. Any microorganisms that use the labeled substrate for their growth could be identified by looking at heavy DNA through the incorporation of the stable isotope. In addition, 13C analyses and metabolic profiling could help determine the fate of the labeled compound and identify 13C-labeled compounds and metabolites, giving insights into the fine mechanisms taking place. Within the framework of the ANR-EndOMiX project, this study aims to monitor and localize the PAH parent compound and its derivatives in soil, plants, and micro-organisms. We combined DNA-SIP with a metabolomic approach to identify the bacteria and fungi active in the degradation of phenanthrene and to follow the fate of phenanthrene (a model PAH compound) in a microbe-plant system. Populus x canadensis was exposed to 12C- or 13C-phenanthrene and harvested over time. Rhizospheric and non-rhizospheric soils as well as root samples were collected after 8, 16, and 24 days. After extraction of the nucleic acids and separation by an isopycnic gradient, the enrichment and labeling of these nucleic acids in the so-called "heavy" fractions for the soil and root samples were demonstrated. Amplifications targeting 16S rRNA and ITS2 were performed on these heavy fractions to identify active bacterial and fungal communities. The results showed a differentiation of communities between soil and roots. Metabolic analyses give us quantitative and qualitative access to phenanthrene and its by-products in soil and roots. Finally, the integration of the data allowed us to propose scenarios concerning the fate of PAHs, molecular mechanisms (RNA-SIP), and microbial actors in soil-plant systems.

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Dates et versions

hal-04754830 , version 1 (26-10-2024)

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  • HAL Id : hal-04754830 , version 1

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Nicolas Gallois, Billet David, Dimitri Heintz, Claire Vilette, Aurélie Cébron. Stable-Isotope Probing unravels fate of phenanthrene in poplar-microbes holobiont and identifies active soil and root endophyte degraders. Applied and Environmental Microbiology Gordon Research Conference, Jul 2023, South Hadley, United States. ⟨hal-04754830⟩
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