The physico-chemical interactions between several types of manufactured TiO2 nanoparticles and two microorganisms, the cyanobacteria Synechocystis (wild type and mutant) and the model bacteria Escherichia coli, were studied in natural and synthetic waters to approach environmental systems. TEM and cryo-TEM techniques were combined to toxicity assessment experiments (colony forming unit) and Reactive Oxygen Species (ROS) quantification in order to define the impact of the sorption extent to the cell mortality. It has been found that the type of electrolyte contained in the natural water controls the aggregation state of the nanoparticles, and thus their sorption capacities. Moreover, a strong correlation exists between the extent of nanoparticles sorption and the cell wall structure, particularly the presence of exopolysaccharides (EPS), thus controlling directly the toxicity of nanoparticles toward the microorganisms. Indeed, mutants of Synechocystis devoided of EPS are by far more sensitive to TiO2-nanoparticles under photocatalysis than the endowed wild type.

TiO<sub>2</sub> nanoparticle interaction with bacteria in natural water: Absorption onto cell wall and cytotoxicity

243rd National Meeting (2012)

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TiO2 nanoparticle interaction with bacteria in natural water: Absorption onto cell wall and cytotoxicity

TiO₂ nanoparticle interaction with bacteria in natural water: Absorption onto cell wall and cytotoxicity