Zero-Valent Iron Nanoparticles Induce Reactive Oxygen Species in the Cyanobacterium, Fremyella diplosiphon

Abstract

Nanoscale zero-valent iron nanoparticles (nZVIs) are known to boost biomass production and lipid yield in Fremyella diplosiphon, a model biodiesel-producing cyanobacterium. However, the impact of nZVI-induced reactive oxygen species (ROS) in F. diplosiphon has not been evaluated. In the present study, ROS in F. diplosiphon strains (B481-WT and B481-SD) generated in response to nZVI-induced oxidative stress were quantified and the enzymatic response determined. Lipid peroxidation as a measure of oxidative stress revealed significantly higher malondialdehyde content (p < 0.01) in both strains treated with 3.2, 12.8, and 51.2 mg L–1 nZVIs compared to untreated control. In addition, ROS in all nZVI-treated cultures treated with 1.6–25.6 mg L–1 nZVIs was significantly higher than the untreated control as determined by the 2′,7′-dichlorodihydrofluorescein diacetate fluorometric probe. Immunodetection using densitometric analysis of iron superoxide dismutase (SOD) revealed significantly higher SOD levels in both strains treated with nZVIs at 51.2 mg L–1. In addition, we observed significantly higher (p < 0.001) SOD levels in the B481-SD strain treated with 6.4 mg L−1 nZVIs compared to 3.2 mg L–1 nZVIs. Validation using transmission electron microscopy equipped with energy-dispersive X-ray spectroscopy (EDS) revealed adsorption of nZVIs with a strong iron peak in both B481-WT and B481-SD strains. While the EDS spectra showed strong signals for iron at 4 and 12 days after treatment, a significant decrease in peak intensity was observed at 20 days. Future efforts will be aimed at studying transduction mechanisms that cause metabolic and epigenetic alterations in response to nZVIs in F. diplosiphon.

Combination effect of cold atmospheric plasma with green synthesized zero-valent iron nanoparticles in the treatment of melanoma cancer model

“…Apart from the anticancer activity of CAP, zero-valent iron nanoparticles (nZVI) have been identified with anticancer properties. The nZVI was originally developed to improve the magnetic properties of iron oxide-based NPs and use for the reduction of the pollutants in wastewater and environmental remediation [11,12], biological applications such as biodieselproducing cyanobacterium [13], and cytotoxicity effect on cancer cells [14][15][16][17]. Previous studies showed that nZVI increases ROS levels in cancer cell lines [14][15][16].…”

Impact of Zero-Valent Iron Nanoparticles and Ampicillin on Adenosine Triphosphate and Lactate Metabolism in the Cyanobacterium Fremyella diplosiphon

“…We hypothesize that the stress could potentially impair the cellular machinery tasked with ATP synthesis, resulting in a significant decline in ATP yield. In a study by Gichuki et al [ 25 ], significant increases in dichlorofluorescein and malondialdehyde content, indicating oxidative stress in F. diplosiphon B481-SD subjected to nZVIs exceeding 3.2 mg/L, were reported. Another possible explanation could be attributed to the interference of nZVIs with the electron transport chain that is integral to photosynthesis, subsequently hampering ATP production [ 26 ].…”

Lipid production and cellular changes in Fremyella diplosiphon exposed to nanoscale zerovalent iron nanoparticles and ampicillin

“…Zero-valent iron nanoparticles used in this study were obtained from Nano Iron company (Rajhrad, Czech Republic). These nZVIs have been previously characterized in our laboratory, and the average particle size determined to be approximately 53 nm [ 17 ]. Ampicillin, one of the β-lactam group antibiotics targeting cellular membranes, was used in this study.…”