Table 1.

The changes of H⁺-fluxes across the bacterial membranes of E. coli K-12, drug-resistant E. coli pARG-25 and S. typhimurium MDC1759 strains in the presence of citric acid coated Fe₃O₄ (100 μg mL⁻¹) stabilized by citric acid, and Ag NPs (10 μg mL⁻¹).

Bacteria and conditions*	H+-fluxes (mmol H+ min−1 (1010 cells)−1	H+-fluxes + DCCD** (mmol H+ min−1 (1010 cells)−1
E. coli K-12 (without NPs)	2.50 ± 0.02	1.10 ± 0.02
E. coli K-12 + Fe3O4 NPs	0.75 ± 0.01 P*** < 0.01	0.68 ± 0.01 P < 0.01
E. coli K-12 + Ag NPs	2.87 ± 0.02 P < 0.05	1.25 ± 0.02 P < 0.05
E. coli pARG-25 (without NPs)	2.32 ± 0.02	1.05 ± 0.02
E. coli pARG-25 + Fe3O4 NPs	1.80 ± 0.02 P < 0.01	0.98 ± 0.01 P < 0.01
E. coli pARG-25 + Ag NPs	2.55 ± 0.02 P < 0.05	1.15 ± 0.01 P < 0.01
S. typhimurium MDC1759 (without NPs)	1.50 ± 0.02	0.83 ± 0.01
S. typhimurium MDC1759 + Fe3O4 NPs	1.16 ± 0.02 P < 0.01	0.27 ± 0.02 P < 0.01
S. typhimurium MDC1759 + Ag NPs	1.32 ± 0.02 P < 0.01	0.34 ± 0.01 P < 0.01

*The bacteria were washed and transferred into Tris–phosphate buffer; bacterial cells were treated with NPs for 10 min.

**The bacterial cells were treated with 0.2 mM DCCD for 10 min.

***P is difference between the values of experimental simples and appropriate control.