Green Synthesis of Silver Nanoparticles Using Mushroom Flammulina velutipes Extract and Their Antibacterial Activity Against Aquatic Pathogens.

In recent years, the biosynthesized silver nanoparticles (AgNPs) have been projected as an alternative to traditional antibiotics for their superior antimicrobial properties and significant inhibition of the biofilm formation. Particularly, it is found that the effectiveness of AgNPs varies greatly with the biomaterial used in their synthesis. Mushrooms are natural resources for excellent antioxidants and bioactive compounds. Nevertheless, there are few reports on the application of mushrooms in AgNPs biosynthesis. In this study, AgNPs were successfully synthesized using Flammulina velutipes extract as reductants and stabilizing agents. The following analyses of UV-visible spectroscopy showed typical absorbance peak at 450 nm. Transmission electron microscope analysis indicated that the prepared AgNPs were monodispersed spheres with an average size of approximately 22 nm. X-ray diffraction analysis confirmed the face-centered cubic (fcc) crystalline structure of metallic silver. Furthermore, the synthesized AgNPs exhibited high stability and antibacterial activities against 6 aquatic pathogens. A subsequent challenge experiment showed that the prepared AgNPs significantly reduced the mortality rate of Ruditapes philippinarum clam infected with Vibrio parahaemolyticus. Notably, AgNPs treatment could inhibit the biofilm formation of the pathogen, indicating that the extracellular synthesis of AgNPs using mushroom can be developed into a novel effective antimicrobial agent to overcome the multidrug-resistant microorganisms in aquaculture. This study will open a new way for edible mushroom processing and wide application in aquaculture. [ABSTRACT FROM AUTHOR]