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Nerol-induced apoptosis associated with the generation of ROS and Ca2+ overload in saprotrophic fungus Aspergillus flavus

Tian, Jun, Gan, Yeyun, Pan, Chao, Zhang, Man, Wang, Xueyan, Tang, Xudong, Peng, Xue
Applied microbiology and biotechnology 2018 v.102 no.15 pp. 6659-6672
Aspergillus flavus, DNA fragmentation, aflatoxins, apoptosis, calcium, caspases, cytochrome c, enzyme activity, fluorescence, food preservation, fungi, ions, mechanism of action, mitochondria, nerol, oxidative stress, phosphatidylserines, reactive oxygen species, saprotrophs
The contamination of food with Aspergillus flavus and subsequent aflatoxins is one of the most serious safety problems in the world. In this study of nerol (NEL)’s antifungal mechanism of action, we observed morphological and physiological changes in Aspergillus flavus. We found that NEL resulted in elevated levels of reactive oxygen species (ROS) and calcium ions (Ca²⁺). On ROS assays, compared with the controls, the proportion of fluorescent cells treated with concentrations of 0.25, 0.5, 1, and 2 μL/mL NEL increased to 8.4 ± 1.07%, 10.2 ± 1.72%, 13.4 ± 0.50%, and 26.2 ± 4.21%, respectively. Increased mitochondrial dysfunction and oxidative stress induced by the interactions between Ca²⁺ and ROS subsequently activate the release of cytochrome c and caspase activity. Characteristic changes of apoptosis were also observed via various detection methods, including phosphatidylserine externalization, nuclear condensation, and DNA fragmentation. Meanwhile, we found that the expression of CaMKs increased significantly in NEL-treated cells. In conclusion, our findings indicate that NEL has great potential as an eco-friendly antifungal agent for food preservation.