title: Response of three biofilm-forming benthic microorganisms to Ag nanoparticles and Ag+: the diatom Nitzschia palea, the green alga Uronema confervicolum and the cyanobacteria Leptolyngbya sp.
abstract: Although the industrial use of nanoparticles has increased over the past decade, the knowledge about their interaction with benthic phototrophic microorganisms in the environment is still limited. This study aims to characterize the toxic effect of ionic Ag+and Ag nanoparticles (citrate-coated silver nanoparticles, AgNPs) in a wide concentration range (from 1 to 1000 μg L-1) and duration of exposure (2, 5 and 14 days) on three biofilm-forming benthic microorganisms: diatom Nitzschia palea, green algae Uronema confervicolum and cyanobacteria Leptolyngbya sp. Ag+has a significant effect on the growth of all three species at low concentrations (1-10 μg L-1), whereas the inhibitory effect of AgNPs was only observed at 1000 μg L-1and solely after 2 days of exposure. The inhibitory effect of both Ag+and AgNPs decreased in the course of the experiments from 2 to 14 days, which can be explained by the progressive excretion of the exopolysaccharides and dissolved organic carbon by the microorganisms, thus allowing them to alleviate the toxic effects of aqueous silver. The lower impact of AgNPs on cells compared to Ag+can be explained in terms of availability, internalization, reactive oxygen species production, dissolved silver concentration and agglomeration of AgNPs. The duration of exposure to Ag+and AgNPs stress is a fundamental parameter controlling the bioaccumulation and detoxification in benthic phototrophic microorganisms.
authors.affiliation: Université de Toulouse, UPS, INP; EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062, Toulouse, France. aridaneglez@gmail.com.|CNRS; EcoLab, 31062, Toulouse, France. aridaneglez@gmail.com.|GET (Géosciences Environnement Toulouse) UMR 5563 CNRS, 14 Avenue Edouard Belin, 31400, Toulouse, France. aridaneglez@gmail.com.
authors.forename: A G
authors.initials: AG
authors.lastname: González
authors.affiliation: Université de Toulouse, UPS, INP; EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062, Toulouse, France.|CNRS; EcoLab, 31062, Toulouse, France.|GET (Géosciences Environnement Toulouse) UMR 5563 CNRS, 14 Avenue Edouard Belin, 31400, Toulouse, France.
authors.forename: L
authors.initials: L
authors.lastname: Fernández-Rojo
authors.affiliation: Université de Toulouse, UPS, INP; EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062, Toulouse, France.|CNRS; EcoLab, 31062, Toulouse, France.
authors.forename: J
authors.initials: J
authors.lastname: Leflaive
authors.affiliation: GET (Géosciences Environnement Toulouse) UMR 5563 CNRS, 14 Avenue Edouard Belin, 31400, Toulouse, France.|BIO-GEO-CLIM Laboratory, Tomsk State University, Tomsk, Russia.|Institute of Ecological Problems of the North, 23 Nab. Severnoi Dviny, Arkhangelsk, Russia.
authors.forename: O S
authors.initials: OS
authors.lastname: Pokrovsky
authors.affiliation: Université de Toulouse, UPS, INP; EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062, Toulouse, France.|CNRS; EcoLab, 31062, Toulouse, France.
authors.forename: J-L
authors.initials: JL
authors.lastname: Rols
mesh_terms: D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D000460:Chlorophyta / Q000187:drug effects* / Q000502:physiology; D000458:Cyanobacteria / Q000187:drug effects* / Q000502:physiology; D017377:Diatoms / Q000187:drug effects* / Q000502:physiology; D053768:Metal Nanoparticles / Q000633:toxicity*; D012834:Silver / Q000633:toxicity*; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D012834:Silver
keywords: AgNPs; Biofilm; Biosorption; Complexation; Growth inhibition; Ionic silver