Green Synthesis of Silver Nanoparticles Using Endophytic Fungi of Panax Notoginseng and Their Antioxidant, Antimicrobial Activities, and its Effect on Cherry Tomato Preservation

Abstract

Endophytic fungi derived from the medicinal plant Panax notoginseng were isolated and characterized. Among them, the filtrate of the endophytic fungus SQ3, identified as Chaetomium globosum, exhibited the ability to effectively reduce silver ions to metallic silver atoms. The resulting green biosynthesized silver nanoparticles (AgNPs) displayed a distinctive surface plasmon resonance peak at 424 nm, with a particle size ranging from 2.92–31.34 nm. In vitro assessments revealed that AgNPs exhibited noteworthy antifungal activity against Phytophthora infestans, Botrytis cinerea and Helminthosporium maydis. AgNPs produce inhibition zones of 17.5 mm, 15.2 mm, and 13.4 mm on Staphylococcus aureus, Escherichia coli, and Bacillus subtilis, respectively. When applied to cherry tomatoes, AgNPs-treated samples inhibited the growth of B. cinerea, reduced weight loss rates, maintained fruit hardness, soluble solids, delay deterioration of cherry tomatoes and prolong storage time, sustained higher superoxide dismutase activity while suppressing the increase of malondialdehyde content. These findings highlight the biological control potential of green biosynthetic AgNPs, positioning them as valuable resources for the development of novel drugs targeting postharvest plant fungal infections.

Keywords: Endophytic fungi, Silver nanoparticles, antioxidant, antimicrobial activity, Biological control