Fungi from metal‐polluted streams may have high ability to cope with the oxidative stress induced by copper oxide nanoparticles

Abstract

Increased commercialization of products based on metal oxide nanoparticles increases the likelihood that these nanoparticles will be released into aquatic environments, thus making relevant the assessment of their potential impacts on aquatic biota. Aquatic fungi are distributed worldwide and play a key role in organic matter turnover in freshwater ecosystems. The present study investigated the impacts of copper oxide spherical nanoparticles (CuO-NPs; <50 nm powder, 5 levels ≤200 mg/L) on cellular targets and antioxidant defenses in 5 fungal isolates collected from metal-polluted or nonpolluted streams. The CuO-NPs induced oxidative stress in aquatic fungi, as evidenced by intracellular accumulation of reactive oxygen species, and led to plasma membrane damage and DNA strand breaks in a concentration-dependent manner. Effects were more pronounced with a longer exposure time (3 d vs 10 d). Under CuO-NP exposure, mycelia of fungi collected from metal-polluted streams showed less oxidative stress and higher activities of superoxide dismutase and glutathione reductase compared with fungi from nonpolluted streams. The latter fungi responded to CuO-NPs with a stronger stimulation of glutathione peroxidase activity. These findings may indicate that fungi isolated from metal-polluted streams had a greater ability to maintain the pool of reduced glutathione than those from nonpolluted streams. Overall, results suggest that populations adapted to metals may develop mechanisms to cope with the oxidative stress induced by metal nanoparticles.

Nanoparticles in the environment: where do we come from, where do we go to?

“…Also in wheat grown on sand, CuO NP reduced root length and simultaneously increased root hair length with no effect on shoot growth, while Cu ions reduced both root and shoot growth [ 159 ]. A recent study by Pradhan et al [ 160 ], however, suggests that aquatic fungi from metal contaminated ecosystems have a higher tolerance towards CuO NP driven by elevated enzymatic activity. This observation may indicate a specific adaptation of fungi towards Cu ions, supporting fungi to withstand CuO NP stress, which might indicate a common mechanism of toxicity.…”

Proteomics and antioxidant enzymes reveal different mechanisms of toxicity induced by ionic and nanoparticulate silver in bacteria

“…18,19 Environmental stress biomarkers and omics are among the most promising next-generation toxicity assessment tools, enhancing measurements of direct and highly sensitive responses to emerging environmental contaminants at the cellular and sub-cellular levels. Freshwater microbes and invertebrates are reported to trigger antioxidant defence mechanisms in response to exposure to metals or metalbased ENPs; these include changes in the activities of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione-S-transferase (GST), [26][27][28] suggesting a role as oxidative stress biomarkers. These enzymes are closely associated with the ascorbate-glutathione cycle, in which the reduced form of glutathione (GSH) is converted to its oxidized form (GSSG), thus maintaining a high GSH : GSSG ratio.…”

Biochemical response of Rhodotorula mucilaginosa and Cladosporium herbarum isolated from aquatic environment on iron(III) ions

“…Extensive metabolic activity of fungi associated with the active production of various exometabolites, causes significant changes in the distribution of metal ions in the aquatic environment and in their mobility, bioavailability, and toxicity 44 . One of the mechanisms of the response of cells to stress caused by heavy metals is the synthesis of reactive oxygen species (ROS) and the related oxidative stress 7,45 . It was evidenced that in cells of the yeast R .…”