Impact of Silver(I) on the Metabolism of Shewanella oneidensis

Abstract

Anaerobic cultures of Shewanella oneidensis MR-1 reduced toxic Ag(I), forming nanoparticles of elemental Ag(0), as confirmed by X-ray diffraction analyses. The addition of 1 to 50 M Ag(I) had a limited impact on growth, while 100 M Ag(I) reduced both the doubling time and cell yields. At this higher Ag(I) concentration transmission electron microscopy showed the accumulation of elemental silver particles within the cell, while at lower concentrations the metal was exclusively reduced and precipitated outside the cell wall. Whole organism metabolite fingerprinting, using the method of Fourier transform infrared spectroscopy analysis of cells grown in a range of silver concentrations, confirmed that there were significant physiological changes at 100 M silver. Principal component-discriminant function analysis scores and loading plots highlighted changes in certain functional groups, notably, lipids, amides I and II, and nucleic acids, as being discriminatory. Molecular analyses confirmed a dramatic drop in cellular yields of both the phospholipid fatty acids and their precursor molecules at high concentrations of silver, suggesting that the structural integrity of the cellular membrane was compromised at high silver concentrations, which was a result of intracellular accumulation of the toxic metal.

Green Synthesis of Silver Nano-particles by Macrococcus bovicus and Its Immobilization onto Montmorillonite Clay for Antimicrobial Functionality

“…3) could be due to the capping by proteins. This is in agreement with previous results [31] which reported that Ag + is reduced during the metabolism of anaerobic cultures of Shewanella oneidensis in presence of high Ag + concentrations (100 μM) and the NSAg forms in aggregates. The crystalline nature of the Ag nano-particles was also confirmed by the powder XRD pattern (Fig.…”

Biofabrication of discrete spherical gold nanoparticles using the metal-reducing bacterium Shewanella oneidensis

“…Due to its versatile nature, it has been used for the bioreduction of various metals -uranium, chromium, iodate, technetium, neptunium, plutonium, palladium, selenite, tellurite, vanadate [31], silver [32,33] -and the oxides of manganese and iron [34]. Here we report on the reduction of aurate (III), using S. oneidensis seeded with aqueous Au 3+ ions at ambient temperature and pressure to produce stable Au 0 .…”

Gold nanoparticle formation using Shewanella oneidensis: a fast biosorption and slow reduction process

“…When this concentration was lowered to 10 µmol L −1 , bacteria survived and were able to keep the Ag(0) out of the cell, and precipitated it on the cell wall. 31 So in the case of Ag, intracellular precipitation was seen at higher concentrations and extracellular precipitation at lower concentrations.…”