title: Effects of silver nitrate and silver nanoparticles on a planktonic community: general trends after short-term exposure.
abstract: Among metal pollutants silver ions are one of the most toxic forms, and have thus been assigned to the highest toxicity class. Its toxicity to a wide range of microorganisms combined with its low toxicity to humans lead to the development of a wealth of silver-based products in many bactericidal applications accounting to more than 1000 nano-technology-based consumer products. Accordingly, silver is a widely distributed metal in the environment originating from its different forms of application as metal, salt and nanoparticle. A realistic assessment of silver nanoparticle toxicity in natural waters is, however, problematic and needs to be linked to experimental approaches. Here we apply metatranscriptome sequencing allowing for elucidating reactions of whole communities present in a water sample to stressors. We compared the toxicity of ionic silver and ligand-free silver nanoparticles by short term exposure on a natural community of aquatic microorganisms. We analyzed the effects of the treatments on metabolic pathways and species composition on the eukaryote metatranscriptome level in order to describe immediate molecular responses of organisms using a community approach. We found significant differences between the samples treated with 5 µg/L AgNO3 compared to the controls, but no significant differences in the samples treated with AgNP compared to the control samples. Statistical analysis yielded 126 genes (KO-IDs) with significant differential expression with a false discovery rate (FDR) <0.05 between the control (KO) and AgNO3 (NO3) groups. A KEGG pathway enrichment analysis showed significant results with a FDR below 0.05 for pathways related to photosynthesis. Our study therefore supports the view that ionic silver rather than silver nanoparticles are responsible for silver toxicity. Nevertheless, our results highlight the strength of metatranscriptome approaches for assessing metal toxicity on aquatic communities.
authors.affiliation: Biodiversity and Centre for Water and Environmental Research, University of Duisburg-Essen, Essen, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Boenigk
authors.affiliation: Genome Informatics, Institute of Human Genetics, Faculty of Medicine, University of Duisburg-Essen, Essen, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Beisser
authors.affiliation: Aquatic Ecology and Centre for Water and Environmental Research, University of Duisburg-Essen, Essen, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Zimmermann
authors.affiliation: Biodiversity and Centre for Water and Environmental Research, University of Duisburg-Essen, Essen, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Bock
authors.affiliation: Technical Chemistry I, University of Duisburg-Essen and Center for Nanointegration Duisburg-Essen (CENIDE), Essen, Germany.
authors.forename: Jurij
authors.initials: J
authors.lastname: Jakobi
authors.affiliation: Aquatic Ecology and Centre for Water and Environmental Research, University of Duisburg-Essen, Essen, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Grabner
authors.affiliation: Biodiversity and Centre for Water and Environmental Research, University of Duisburg-Essen, Essen, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Groβmann
authors.affiliation: Genome Informatics, Institute of Human Genetics, Faculty of Medicine, University of Duisburg-Essen, Essen, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Rahmann
authors.affiliation: Technical Chemistry I, University of Duisburg-Essen and Center for Nanointegration Duisburg-Essen (CENIDE), Essen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Barcikowski
authors.affiliation: Aquatic Ecology and Centre for Water and Environmental Research, University of Duisburg-Essen, Essen, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Sures
mesh_terms: D002452:Cell Count; D004781:Environmental Exposure; D053768:Metal Nanoparticles / Q000633:toxicity / Q000648:ultrastructure; D058977:Molecular Sequence Annotation; D010316:Particle Size; D010933:Plankton / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development*; D017422:Sequence Analysis, DNA; D012834:Silver / Q000633:toxicity*; D012835:Silver Nitrate / Q000633:toxicity*; D013057:Spectrum Analysis; D013997:Time Factors; D059467:Transcriptome / Q000235:genetics; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D012834:Silver; D012835:Silver Nitrate
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