Metabolomic and proteomic investigations of impacts of titanium dioxide nanoparticles on Escherichia coli

Mariane Planchon (1, 2) , Thibaut Léger (3) , Olivier Spalla (4) , Gaspard Huber (2) , Roselyne Ferrari (5)

1 IPGP - Institut de Physique du Globe de Paris
2 LSDRM - Laboratoire Structure et Dynamique par Résonance Magnétique (LCF)
3 IJM (UMR_7592) - Institut Jacques Monod
4 LIONS - Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire
5 LIED (UMR_8236) - Laboratoire Interdisciplinaire des Energies de Demain

In a previous study, it was demonstrated that the toxic impact of titanium dioxide nanoparticles on Escherichia coli starts at 10 ppm and is closely related to the presence of little aggregates. It was also assumed that only a part of the bacterial population is able to adapt to this stress and attempts to survive. Proteomic analyses, supported by results from metabolo-mics, reveal that exposure of $E. coli$ to nano-TiO$_2$ induces two main effects on bacterial metabolism: firstly, the up-regulation of proteins and the increase of metabolites related to energy and growth metabolism; secondly, the down-regulation of other proteins resulting in an increase of metabolites, particularly amino acids. Some proteins, e.g. chaperonin 1 or isocitrate dehydrogenase, and some metabolites, e.g. phenylalanine or valine, might be used as biomarkers of nanoparticles stress. Astonishingly, the ATP content gradually rises in relation with the nano-TiO$_2$ concentration in the medium, indicating a dramatic release of ATP by the damaged cells. These apparently contradictory results accredit the thesis of a heterogeneity of the bacterial population. This heterogeneity is also confirmed by SEM images which show that while some bacteria are fully covered by nano-TiO$_2$ , the major part of the bacterial population remains free from nanoparticles, resulting in a difference of prote-ome and metabolome. The use of combined–omics has allowed to better understand the heterogeneous bacterial response to nano-TiO$_2$ stress due to heterogeneous contacts between the protagonists under environmental conditions.

Domains: Material chemistry

Mariane Planchon, Thibaut Léger, Olivier Spalla, Gaspard Huber, Roselyne Ferrari. Metabolomic and proteomic investigations of impacts of titanium dioxide nanoparticles on Escherichia coli. PLoS ONE, 2017, 12, pp.0178437. ⟨10.1371/journal.pone.0178437.s008⟩. ⟨cea-01532100⟩