Oxidative Stress Response of Selenium Nanoparticles to Copper Stress in Aspergillus flavus TL-F3
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.