Fig 1.
The characterization of different sizes of silver nanoparticles by TEM.
TEM images of (a) nano-Ag 10 and (c) nano-Ag 50. Frequency of size distribution for (b) nano-Ag 10 and (d) nano-Ag 50; scale bar: 100nm.
Table 1.
Characterization of AgNPs.
Fig 2.
Effect of two different sizes of AgNPs on the growth of A. vinelandii.
(a) nano-Ag 10 and (b) nano-Ag 50. The bacteria were cultured for 48 h in media with and without AgNPs.
Fig 3.
The effect of AgNPs on the cell morphology of A. vinelandii observed by SEM (upper) and TEM (lower).
(a) SEM and (b) TEM images of a control group in which no AgNPs are added; (c) SEM and (d) TEM images of nano-Ag 10 at a concentration of 10 mg/L; (e) SEM and (f) TEM images of nano-Ag 50 at a concentration of 100 mg/L. All treatment groups were exposed for 12 h.
Fig 4.
Effect of AgNPs on cell apoptosis of A. vinelandii.
(a) nano-Ag 10 at a concentration of 2 mg/L; (b) nano-Ag 10 at a concentration of 10 mg/L; (c) nano- Ag50 at a concentration of 10 mg/L; (d) nano-Ag 50 at a concentration of 100 mg/L; (e) no AgNPs added. All treatments were exposed for 12 h.
Fig 5.
Nitrogenase activity (a) and relative expression of nifH (b) of A. vinelandii exposed to AgNPs for 12 h.
Fig 6.
Changes in intracellular ROS levels of A.vinelandii (a) and generation of hydroxyl radicals by two sizes of AgNPs (b).
Electron spin resonance (ESR) spectra were obtained from samples containing 50 mM DMPO + 0.5 mM H2O2 + 10 mM pH 3.6 HAc-NaAc in the presence of control (1), 2 mg/L (2), 10 mg/L (3) of nano-Ag 10, and 10 mg/L (4), 100 mg/L (5) of nano-Ag 50, respectively.
Fig 7.
Intracellular and membrane Ag contents of control cells and cells treated with two size of AgNPs for 12h.
(a) nano-Ag 10 and (b) nano-Ag 50.
Fig 8.
Possible toxicity mechanism for AgNPs in A.vinelandii.