Effects of Titanium Dioxide Nanoparticles on Bacteria Community Composition Under Snail Grazing Pressure

In 2013, the King and Matson labs at Baylor University conducted an outdoor stream mesocosm study at the Baylor Experimental Aquatic Research (BEAR) facility using wastewater treatment plant effluent and P25 titanium dioxide nanoparticles (TiO2NPs). A study of the effects of snail grazing and TiO2NPs on the algal and bacterial components of the periphyton in the top pools showed that bacterial cell densities were unaffected by the presence of the TiO2NPs, but the algal cell densities were affected in the low dose streams. In order to explore the mechanisms driving the trends observed, an indoor stream microcosm (Baby BEAR) was conducted. Two species of snails were used, and the periphyton was exposed to similar concentrations of TiO2 nanoparticles that were used in the outdoor mesocosm study. 16S rRNA sequencing was used to identify 17 bacterial orders that increased in the treated streams relative to the controls.