Implications of handling practices on the ecotoxic profile of alumina nanoparticles towards the bacteria Vibrio fischeri

Impact of global change on environmental hazards of different clays: A case study on Aliivibrio fischeri

The effects of global change in marine ecosystems are expected to lower pH from the current 8.1-7.5-7.0, which will have significant impacts on marine species. The purpose of this study is to investigate whether the ecotoxicity of ten different natural clays change significantly in response to the acidification process and what factors are associated with the observed changes. In this study, the ecotoxicological response of a bacterium (Aliivibrio fischeri) was tested under current (pH= 8.1) and acidified (pH 7.5 and 7.0) conditions. The ecotoxicity detected in the solid phase test (SPT protocol) and in the contact water was affected by the pH, which increased the ecotoxicity from 2/10 clays (pH 8.10) to 7/10 clays (pH 7.00), also shifting the detected effects from low to high toxicity values. The analyses performed on the natural clays studied show that pH can affect the release of metals, metalloids and rare earths from the clays into the contact water phase, affecting the toxicity observed. This phenomenon depends on the type of clay and is closely related to its mineralogical composition. As consequence, in a globally changing scenario, ecotoxicity, even of natural materials such as clay, cannot be considered stable, but must be accurately revaluated depending on the mineralogical and chemical composition of the clay. Moreover, the mineralogical composition of clays showed different efficiency in absorbing bacteria on the surface of clay particles. It was found that live bacterial cells were absorbed on the clay surface in numbers that were dependent on both clay types and pH levels.

Ecotoxicological assessment of magnetite and magnetite/Ag nanoparticles on terrestrial and aquatic biota from different trophic levels

The aim of the study is an ecotoxicological assessment of magnetite iron oxide-based nanoparticles (NPs), which have risen in popularity in the last decade, on selected terrestrial and aquatic organisms from various levels of the food chain. In the presented study various organisms, from both the terrestrial and aquatic environment, were used as targets for the assessment of NPs ecotoxicity. Plants (radish, oat), marine bacteria (A. fischeri) and crustacean (H. incongruens) were used to represent producers, decomposers, and consumers, respectively. It was found that examined NPs were harmful (to a different degree) to biota from three different trophic levels. Physicochemical characterization (size/morphology, crystallinity, composition, and magnetic properties) of the tested nanoparticles was performed by: transmission electron microscopy, X-ray diffraction, energy dispersive spectroscopy, and Mossbauer spectroscopy, respectively. Phytotoxicity was evaluated according to the OECD 208 Guideline, while acute and chronic toxicity of NPs was conducted using bioassays employing bacteria and crustacea, respectively. The phytotoxicity of all investigated iron oxide-based NPs was dependent on concentration and type of NPs formulation and was measured via biomass, seed germination, root length, shoot height, and content of plant pigments. Increasing the concentration of NPs increased phytotoxicity and mortality of aquatic organisms. Ecotoxicity of iron oxide/silver was dependent on the size and content of silver. Iron oxide NPs coated with nanosilver in a percentage ratio of 69/31 were found to be the most toxic on tested terrestrial and aquatic biota.

Vibrio fischeri bioluminescence inhibition assay for ecotoxicity assessment: A review

Vibrio fischeri bioluminescence inhibition bioassay (VFBIA) has been widely applied for the monitoring of toxicity on account of multiple advantages encompassing shorter test duration, sensitive, cost-effective and ease of operation. Moreover, this bioassay found to be equally applicable to all types of matrices (organic & inorganic compounds, metals, wastewater, river water, sewage sludge, landfill leachate, herbicides, treated wastewater etc.) for toxicity monitoring. This review highlights the apparent significance of Vibrio fischeri bioluminescence inhibition assay for ecotoxicological screening and evaluation of diverse chemical substances toxicity profile. The biochemical and genetic basis of the bioluminescence assay and its regulatory mechanism have been concisely discussed. The basic test protocol with ongoing improvements, widespread applications, typical advantages and probable limitations of the assay have been overviewed. The sensitivity of VFBIA and toxicity bioassays has also been compared.

Influence of the stabilizers on the toxicity of metallic nanomaterials in aquatic organisms and human cell lines

In this study, following a systematic approach, we used aquatic species (bacteria Vibrio fischeri and microalgae Raphidocelis subcapitata) and different human cell lines (Caco-2, HepG2, SV-80 and HaCaT) representing different tissues and exposure pathways, to investigate how two organic stabilizers (PVA and DMSO) used for NMs dispersion influence their physicochemical properties, the persistence of metals in suspension and the toxicity/ecotoxicity of two metallic NMs (nano-Ag and nano-Cu). Although the stabilizers are expected to contribute to improve the dispersion and stability of NMs, the results obtained clearly showed that no similar changes in toxicity and morphological properties of the nano-Ag can be expected after its stabilization with PVA. Thus, regarding human cell lines, the reduction in the average size of the PVA-nano-Ag was followed by a reduction or maintenance of its toxicity, but the opposite was observed for the aquatic species tested since an increase in the average size enhanced its toxicity. As far as nano-Cu is considered DMSO contributed for a better dispersion of this nanomaterial, however this was not translated in a similar toxicity/ecotoxicity modification. In summary, even for nano-Cu, for which few or no data exists regarding its toxicity after stabilization with organic compounds, it was confirmed with consistent data, that the toxicity of metallic NMs is a complex combination of average size, chemical composition, solubilization or persistence in suspension of the metallic forms, interaction with test medium components and sensitivity of test species and cell lines. The combination of all of these factors makes the toxicity of metallic NMs unpredictable and points for the need of an extensive evaluation of each new formulation.