Key Takeaways & Executive Findings
- •• • At 50 mg·L−1 Cu2+ stress, 0.25 mg·L−1 SeNPs increased A. flavus TL-F3 biomass by 2.71%, demonstrating a protective effect that could enhance fungal biomass production in bioremediation applications. • • SeNPs elevated GPX and GR activities by 17.2% and 23.94%, respectively, and increased GSH content by 18.59%, indicating a strengthened antioxidant defense that mitigates Cu2+-induced oxidative stress. • • The maximum Cu2+ removal rate of 56.32% was achieved at 50 mg·L−1 Cu2+ without SeNPs, establishing a baseline for fungal copper uptake efficiency under optimized conditions. • • FTIR analysis identified carboxylic acid, alcohol, phenol, and phosphate/sulfate groups as potential Cu2+ binding sites, providing a mechanistic basis for biosorption and guiding surface modification strategies.
Abstract
This study investigated the effects of selenium nanoparticles (SeNPs) on the growth, mycelium morphology, copper (Cu2+) removal rate, extracellular polymeric substances (EPS), and intracellular enzyme activity of Aspergillus flavus TL-F3 (A. flavus TL-F3) under Cu2+ stress. Results showed that different concentrations of Cu2+ inhibited the growth of A. flavus TL-F3. The highest Cu2+ removal rate of 56.32% was observed at a Cu2+ concentration of 50 mg·L−1. Under 50 mg·L−1 Cu2+ stress, 0.25 mg·L−1 SeNPs promoted the growth of A. flavus TL-F3, increasing its biomass by 2.71%, and significantly enhanced the fluorescence intensity of EPS, Na+/K+-ATPase activity, and decreased malondialdehyde (MDA) content, reduced superoxide dismutase (SOD) and catalase (CAT) enzyme activities. Additionally, SeNPs stimulated the glutathione (GSH-GSSG) cycle in A. flavus TL-F3, elevating glutathione peroxidase (GPX) and glutathione reductase (GR) activity by 17.2% and 23.94%, respectively, and increasing reduced glutathione (GSH) content by 18.59%, and decreasing the GSH/GSSG ratio, thereby effectively alleviating Cu2+ toxicity. Fourier transform infrared spectroscopy indicated that surface functional groups of A. flavus TL-F3, including carboxylic acid, alcohol, phenol, and phosphate/sulfate functional groups, might bind with Cu2+, enhancing its tolerance to Cu2+. This study enriches the theoretical knowledge of microorganism-heavy metal interactions and provides deeper insights into microbial heavy metal resistance mechanisms.
1. Introduction
Heavy metal contamination of water bodies remains a critical environmental challenge due to the persistence, high toxicity, and carcinogenicity of metals such as copper. Copper, widely used in alloys, printed circuit boards, mining, and electroplating, frequently enters wastewater streams, posing severe risks to ecosystems and human health. Conventional physicochemical remediation methods are often cost-prohibitive or generate secondary pollution, necessitating sustainable biological alternatives. Fungi, particularly Aspergillus species, exhibit inherent metal tolerance and biosorption capabilities, yet their efficiency is often limited by metal-induced oxidative stress and growth inhibition.
This study addresses the bottleneck by investigating the role of selenium nanoparticles (SeNPs) in enhancing the copper stress tolerance of Aspergillus flavus TL-F3, a strain isolated from copper tailings. The experimental protocol systematically evaluates growth, copper removal, extracellular polymeric substances, and intracellular antioxidant enzyme activities, revealing that SeNPs at 0.25 mg·L−1 significantly mitigate Cu2+ toxicity by upregulating the glutathione cycle and reducing oxidative damage. These findings provide a mechanistic basis for developing SeNP-assisted fungal bioremediation strategies, potentially improving metal removal efficiency and biomass stability under heavy metal stress.
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YUE Yuchen, ZHU Tingting, CHEN Nuo, WANG Binhao, GAO Yuci, JIANG Yehong, FAN Ting (2026). Oxidative Stress Response of Selenium Nanoparticles to Copper Stress in Aspergillus flavus TL-F3. Environmental Chemistry. https://doi.org/10.7524/j.issn.0254-6108.2025051701
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Frequently Asked Questions
What is the optimal SeNPs concentration for enhancing Cu2+ tolerance in A. flavus TL-F3, and how does it affect biomass and copper removal?
Under 50 mg·L−1 Cu2+ stress, 0.25 mg·L−1 SeNPs increased biomass by 2.71% and enhanced EPS fluorescence intensity, while the Cu2+ removal rate reached 56.32% at 50 mg·L−1 Cu2+ without SeNPs. SeNPs did not directly increase removal but improved fungal growth and antioxidant capacity.
How do SeNPs modulate the antioxidant enzyme system in A. flavus TL-F3 under copper stress?
SeNPs significantly increased GPX and GR activities by 17.2% and 23.94%, respectively, and elevated GSH content by 18.59%, while decreasing the GSH/GSSG ratio. This indicates an enhanced glutathione cycle that helps mitigate Cu2+-induced oxidative stress.
What are the key functional groups involved in Cu2+ biosorption by A. flavus TL-F3, and how might SeNPs influence these interactions?
FTIR analysis identified carboxylic acid, alcohol, phenol, and phosphate/sulfate groups as potential Cu2+ binding sites. SeNPs may alter the surface chemistry or EPS composition, potentially affecting metal binding and tolerance, though the exact mechanism requires further investigation.
What is the maximum Cu2+ removal rate achieved by A. flavus TL-F3, and under what conditions?
The maximum Cu2+ removal rate of 56.32% was observed at a Cu2+ concentration of 50 mg·L−1 without SeNPs. This suggests that A. flavus TL-F3 has intrinsic copper removal capability, which could be optimized for bioremediation applications.
How does SeNPs affect the activity of Na+/K+-ATPase and MDA content, and what does this imply for cellular integrity?
SeNPs increased Na+/K+-ATPase activity and decreased MDA content, indicating improved membrane integrity and reduced lipid peroxidation. This suggests that SeNPs help maintain cellular homeostasis under copper stress, contributing to enhanced fungal viability.
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