Exposure of Metal Oxide Nanoparticles on the Bioluminescence Process of P(u)- and P(m)-lux Recombinant P. putida mt-2 Strains

Comparison of the effects of metal oxide nanoparticles (NPs; CuO, NiO, ZnO, TiO(2), and Al(2)O(3)) on different bioluminescence processes was evaluated using two recombinant (P(m)-lux and P(u)-lux) strains of Pseudomonas putida mt-2 with same inducer exposure. Different sensitivities and responses were observed according to the type of NPs and recombinant strains. EC(50) values were determined. The negative effects on the bioluminescence activity of the P(m)-lux strain was greater than for the P(u)-lux strains for all NPs tested. EC(50) values for the P(m)-lux strain were 1.7- to 6.2-fold lower (corresponding to high inhibition) than for P(u)-lux. ZnO NP caused the greatest inhibition among the tested NPs in both strains, showing approximately 11 times less EC(50s) of CuO, which appeared as the least inhibited. Although NPs showed different sensitivities depending on the bioluminescence process, similar orders of EC(50s) for both strains were observed as follows: ZnO > NiO, Al(2)O(3) > TiO(2) > CuO. More detailed in-depth systematic approaches, including in the field of molecular mechanisms, is needed to evaluate the accurate effect mechanisms involved in both bioluminescence metabolic processes.