Effect of TiO-nanoparticles on copper toxicity to bacteria: role of bacterial surface.

The impact of titanium dioxide nanoparticles (nano-TiO) on the aquatic environment is an important issue due to their increasing application. Although nano-TiO was reported to show an effect on heavy metal toxicity to aquatic organisms, the underlying mechanism is not well understood. In this study, two bacterial species ( () and ()) from sediment were selected to study the effects of nano-TiO on copper toxicity. Nano-TiO was found to inhibit the growth of and enhance the oxidative stress damage caused by copper, whereas these effects were not observed for . Transmission electron microscopy and flow cytometry showed that has stronger association ability to nano-TiO than . The existence of the S-layer on the surface of might be the possible reason, leading to the difference in copper toxicity. This indicates that the characteristics of bacterial surfaces might be important to the toxicity responses of nanoparticles.