title: A novel method for comparison of biocidal properties of nanomaterials to bacteria, yeasts and algae.
abstract: Toxicity testing of nanomaterials (NMs) is experimentally challenging because NMs may interfere with test environment and assay components. In this work we propose a simple and reliable method--a 'spot test' to compare biocidal potency of NMs to unicellular microorganisms such as bacteria, yeasts and algae. The assay is straightforward: cells are incubated in deionized water suspensions of NMs for up to 24h and then pipetted as a 'spot' on agarized medium. Altogether seven bacterial strains, yeast and a microalga were tested. CuO, TiO2 and two different Ag NPs, multi-wall C-nanotubes (MWCNTs), AgNO3, CuSO4, 3,5-dichlorophenol, triclosan and H2O2 were analyzed. The biocidal potency of tested substances ranged from 0.1mg/L to >1000 mg/L; whereas, the least potent NMs toward all test species were TiO2 NPs and MWCNTs and most potent Ag and CuO NPs. Based on the similar toxicity pattern of the tested chemicals on the nine unicellular organisms in deionized water we conclude that toxicity mechanism of biocidal chemicals seems to be similar, whatever the organism (bacteria, yeast, alga). Therefore, when the organisms are not 'protected' by their environment that usually includes various organic and inorganic supplements their tolerance to toxicants is chemical- rather than organism-dependent.
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia; Faculty of Chemical and Materials Technology, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia. Electronic address: sandra.suppi@kbfi.ee.
authors.forename: Sandra
authors.initials: S
authors.lastname: Suppi
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia. Electronic address: kaja.kasemets@kbfi.ee.
authors.forename: Kaja
authors.initials: K
authors.lastname: Kasemets
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia. Electronic address: angela.ivask@kbfi.ee.
authors.forename: Angela
authors.initials: A
authors.lastname: Ivask
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia. Electronic address: kai.kunnis@kbfi.ee.
authors.forename: Kai
authors.initials: K
authors.lastname: Künnis-Beres
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia. Electronic address: mariliis.sihtmae@kbfi.ee.
authors.forename: Mariliis
authors.initials: M
authors.lastname: Sihtmäe
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia. Electronic address: imbi.kurvet@kbfi.ee.
authors.forename: Imbi
authors.initials: I
authors.lastname: Kurvet
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia. Electronic address: villem.aruoja@kbfi.ee.
authors.forename: Villem
authors.initials: V
authors.lastname: Aruoja
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia. Electronic address: anne.kahru@kbfi.ee.
authors.forename: Anne
authors.initials: A
authors.lastname: Kahru
mesh_terms: D000362:Agar / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry; D002733:Chlorophenols / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D019327:Copper Sulfate / Q000737:chemistry; D003470:Culture Media / Q000737:chemistry; D004926:Escherichia coli / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D019216:Metals, Heavy; D008826:Microbial Sensitivity Tests; D049329:Nanostructures / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000187:drug effects*; D012834:Silver / Q000737:chemistry*; D012835:Silver Nitrate / Q000737:chemistry; D013211:Staphylococcus aureus / Q000187:drug effects*; D013696:Temperature; D014025:Titanium / Q000737:chemistry; D018675:Toxicity Tests; D014260:Triclosan / Q000737:chemistry; D014873:Water Pollutants / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D002733:Chlorophenols; D003470:Culture Media; D019216:Metals, Heavy; D037742:Nanotubes, Carbon; D014873:Water Pollutants; C009495:titanium dioxide; D012834:Silver; D014260:Triclosan; D003300:Copper; D000362:Agar; D012835:Silver Nitrate; D006861:Hydrogen Peroxide; D014025:Titanium; C116190:3,5-dichlorophenol; D019327:Copper Sulfate; C030973:cupric oxide
keywords: Bioavailability; Heavy metals; Minimum biocidal concentration; Nanoparticles; Toxicity