Involvement of ROS in nanosilver-caused suppression of aflatoxin production from Aspergillus flavus

Silver nanoparticles (AgNPs) have been extensively studied as antimicrobial materials, but their capability of suppressing aflatoxin production has not been investigated. In this work, AgNPs with an average size of 4.5 nm were synthesized to inhibit the growth of Aspergillus flavus (A. flavus). Based on the anti-fungal assay, the concentration of 5 μg mL−1 was chosen to study the direct inhibiting effects of AgNPs on aflatoxin production. Results show that AgNP treatment could significantly decrease secretion of aflatoxin B1 from A. flavus. Real-time measurements of O2− with an electrochemical sensor reveal that the AgNPs could trigger the release of O2− from fungal mycelia. A mechanism involving O2− release is proposed to explain AgNP-caused depression of aflatoxin production from A. flavus. This is the first attempt to study AgNP-induced inhibition on aflatoxin generation and its possible mechanisms.