4 results on '"Laurent, Fabrice Martin"'
Search Results
2. Antibiotics favor the establishment of antibiotrophic bacteria in agricultural soil microbial communities, but are not always sufficient to enhance antibiotic-degradation: manure spreading can help
- Author
-
Loren Billet, Stéphane Pesce, Nadine Rouard, Aymé Spor, Laurent Fabrice Martin, Marion Devers Lamrani, EL Mjiyad, Noureddine, INRAE, centre de Lyon-Villeurbanne, Agroécologie [Dijon], and Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
- Subjects
[SDE] Environmental Sciences ,[SDE]Environmental Sciences - Abstract
International audience; During the past decades, environmental concentrations of antibiotics have largely increased,resulting in a risk of ecosystem disturbance. However, because their composition is often rich innitrogen and carbon, antibiotics are of nutritional interest for microorganisms, as long as theirbiocidal character is not considered. Antibiotic-degrading bacteria have therefore emerged amongststrains that were resistant to antibiotics. Called antibiotrophs, they are able to use selectedantibiotics as nutritive sources for their growth. While several antibiotrophs have been isolated fromdifferent agroecosystems, little is known about their ecology. In particular, their dispersal capacity ispoorly evaluated, even though manure spreading is a suspected source of antibiotrophs foragroecosystems. Also, their antibiotic degradation ability in complex agricultural soil communitiesremains insufficiently studied.In this context, a microcosm experiment was set up by inoculating the sulfonamide-degrading andresistant bacterium, Microbacterium sp. C448, in four different soil types supplied or not withsulfamethazine and/or swine manure. After one month of incubation, qPCR analyses and 16S rDNAsequencing were performed to respectively quantify the inoculated strain, its antibiotrophic genesadA, and to characterize the structure of bacterial communities. In parallel, a similar experimentwas carried out with the addition of radiolabeled sulfamethazine, in order to monitoredantibiotrophy activity during incubation by radiorespirometry.Quantitative PCR results showed an effective establishment of the strain and its sulfamethazinedegradinggene (sadA) only under sulfamethazine selection pressure. This reflects the lowcompetitiveness of the strain, which possesses a low invasion potential under non-antibioticcontaminated conditions. Sulfamethazine treated soils differed in their capacity to mineralize theantibiotic. Indeed, in absence of manure and despite the presence of Microbacterium sp. C448, onlyone of the four tested soils exhibited slight mineralization capacities. Whatever the soil type,radiorespirometry analyses showed that manure addition significantly enhanced sulfamethazinemineralization. These results confirm that the presence of functional genes does not necessarilyensure functionality. Moreover, they suggest that sulfamethazine does not necessarily confer aselective advantage to the degrading strain, as a nutritional source. In addition, 16S rDNA sequencinganalyses strongly suggest that sulfamethazine has released trophic niches by biocidal action.Accordingly, manure-originating bacteria and/or Microbacterium sp C448 could have access to lowcompetition or competition-free trophic niches. However, simultaneous inputs of manure and of thestrain could induce detrimental competition for Microbacterium sp. C448, thus forcing it to usesulfamethazine as a nutritional source. Altogether, these results suggest that the studiedantibiotrophic strain can modulate its sulfamethazine-degradation function depending on microbialcompetition and resource accessibility, to establish in an agricultural soil. Most importantly, this workhighlights an increased dispersal potential of antibiotrophs in antibiotic-polluted environments, asantibiotics can not only release existing trophic niches but also constitute new ones.
- Published
- 2020
3. Ecological Recovery and Resilience in Environmental Risk Assessments at the European Food Safety Authority
- Author
-
Brock, Theordorus, Bigler, Franz, Frampton, Geoff, Hogstrand, Christer, Luttik, Robert, Laurent, Fabrice Martin, Topping, Christopher John, Vand den Werf, Wopke, and Rortais, Agnes
- Subjects
Environmental Risk Assessment ,WIMEK ,Internal and external recovery ,Ecological resilience ,PE&RC ,Systems approach ,ECOSYSTEM-SERVICES ,PESTICIDES ,INSECTICIDE ,Normal operating range ,MANAGEMENT ,Ecosystem services delivery ,Crop and Weed Ecology ,RESPONSES - Abstract
A conceptual framework was developed by a working group of the Scientific Committee of the European Food Safety Authority (EFSA) to guide risk assessors and risk managers on when and how to integrate ecological recovery and resilience assessments into environmental risk assessments (ERA). In this commentary we advocate that a systems approach is required to integrate the diversity of ecosystem services (ES) providing units, environmental factors, scales, and stressor-related responses necessary to address the context dependency of recovery and resilience in agricultural landscapes. A future challenge in the resilience assessment remains to identify the relevant bundles of ecosystem services provided by different types of agroecosystem that need to be assessed in concert. Integr Environ Assess Manag 2018;14:586-591. (c) 2018 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC)
- Published
- 2018
- Full Text
- View/download PDF
4. The millimetre-scale distribution of 2,4-D and its degraders drives the fate of 2,4-D at the soil core scale.
- Author
-
Pinheiro, Marc, Garnier, Patricia, Beguet, Jérémy, Laurent, Fabrice Martin, and Gonod, Laure Vieublé
- Subjects
- *
ORGANIC compound content of soils , *SOIL corrosion , *ECOSYSTEM services , *SOIL fertility , *WATER quality , *BIODEGRADATION - Abstract
The biodegradation of organic compounds in soil is a key process that has major implications for different ecosystem services such as soil fertility, air and water quality, and climate regulation. Due to the complexity of soil, the distributions of organic compounds and microorganisms are heterogeneous on sub-cm scales, and biodegradation is therefore partly controlled by the respective localizations of organic substrates and degraders. If they are not co-localized, transfer processes become crucial for the accessibility and availability of the substrate to degraders. This spatial interaction is still poorly understood, leading to poor predictions of organic compound dynamics in soils. The objectives of this work were to better understand how the mm-scale distribution of a model pesticide, 2,4-dichlorophenoxyacetic acid (2,4-D), and its degraders drives the fate of 2,4-D at the cm soil core scale. We constructed cm-scale soil cores combining sterilized and "natural" soil aggregates in which we controlled the initial distributions of 2,4-D and soil microorganisms with the following spatial distributions: i) a homogeneous distribution of microorganisms and 2,4-D at the core-scale, ii) a co-localized distribution of microorganisms and 2,4-D in a single spot (360 mm³) and iii) a disjoint localization of microorganisms and 2,4-D in 2 soil spots (360 mm³) separated by 2 cm. Two sets of experiments were performed: one used radiolabeled 14C-2,4-D to study the fate of 2,4-D, and the other used 12C-2,4-D to follow the dynamics of degraders. Microcosms were incubated at 20 °C and at field capacity (−31.6 kPa). At the core scale, we followed 2,4-D mineralization over time. On three dates, soil cores with microorganisms and 2,4-D localized in soil spots, were cut out in slices and then in 360 mm³ soil cubes. The individual soil cubes were then independently analysed for extractable and non-extractable 14C and for degraders (quantitative PCR of tfdA genes). Knowing the initial position of each soil cube allowed us to establish 3D maps of 2,4-D residues and degraders in soil. The results indicated that microorganisms and pesticide localizations in soil are major driving factors of i) pesticide biodegradation, by regulating the accessibility of 2,4-D to degrading microorganisms (by diffusion); and ii) the formation of non-extractable residues (NER). These results also emphasized the dominant role of microorganisms in the formation and localization of biogenic NER at a mm-scale. To conclude, these results demonstrate the importance of considering micro-scale processes to better understand the fate of pesticides and more generally of soil organic substrates at upper scales in soil and suggest that such spatial heterogeneity should not be neglected when predicting the fate of organic compounds in soils. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.