Assessment of nanoscale zero-valent iron toxicity towards several bacterial species by specific marker of oxidative stress monitoring
Abstract
Nanoscale zero-valent iron (nZVI) is a newly developed nanomaterial used in remediation technologies. As a result of its very high efficiency in degradation of various inorganic and organic pollutants, the worldwide application of nZVI is rapidly increasing.
These iron nanoparticles are being introduced in high amounts (up to 20 g/L) to the environment even though their toxicity has not yet been properly investigated. The presented study includes a novel approach for toxicity determination of nZVI and for monitoring of its impact on 6 bacterial species (typical representatives of exposed organisms).
The assay is based on oxidative stress marker formation in bacterial cultures after short term exposition to nanoparticles. The monitored marker is one of the most common toxic and mutagenic products of lipid peroxidation/degradation - malondialdehyde.
During the toxicity testing of iron nanomaterials the bacterial cultures were extracted after exposition to nZVI and then malondialdehyde in the extract was derivatized. Determination and quantification of the derivatised marker were performed by HPLC with fluorescence detection.
The results show high variability in specific toxicity towards the bacteria species even in the same genus. There was not a significant difference in toxicity between Gram positive and negative bacteria, but the production of malondialdehyde shows great dependence on bacterial size (i.e. surface).
The results of this study show that the specific oxidative stress marker analysis enables determination and comparison of toxicity of nZVI and its derived nanomaterials on bacteria species before their direct use in the environment.