1 Impact of TiO 2 nanoparticles on freshwater bacteria from three Swedish lakes Julia Farkas 1* ‡, Hannes Peter 2 ‡, Tomasz M. Ciesielski 1 , Kevin V. Thomas 3 , Ruben Sommaruga 2 , Willi Salvenmoser 4 , Gesa A. Weyhenmeyer 5 , Lars J. Tranvik 5 , Bjørn M. Jenssen 1 1 Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway 2 Institute of Ecology, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria 3 Norwegian Institute of Water Research, Gaustadalléen 21, 0349 Oslo, Norway 4 Institute of Zoology, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria 5 Department of Ecology and Genetics/Limnology, Uppsala University, PO Box 573, 75123 Uppsala, Sweden *corresponding author Julia Farkas* Høgskoleringen 5 7491 Trondheim Norway email: julia.farkas@ntnu.no +4746259902