Green-synthesis and optimization of an eco-friendly nanobiofungicide from Bacillus amyloliquefaciens MH046937 with antimicrobial potential against phytopathogens

Abstract Plant diseases caused by soil pathogenic fungi are threatening plant crops worldwide. The aim of this study focuses on the synthesis of silver nanoparticles by a biological method using Bacillus amyloliquefaciens MH046937 as a new source. For attaining maximum biosynthesis of nano-silver an orthogonal array of five-four level factors (L16 45) was applied to determine optimum conditions for maximum bacterial biomass production. The biosynthesized silver nanoparticles are characterized using UV-vis spectrophotometer, Transmission electron microscope and Dynamic Light Scattering (DLS). AgNPs were tested for its antibacterial and antifungal potential against Gram-positive, Gram-negative bacteria strains and fungi strains. In-vitro studies revealed good antifungal effects of AgNPs against phytopathogenic F. oxysporium (33 mm IZD) and F. solani (26 mm IZD). In the greenhouse experiment, AgNPs caused a remarkable enhancement in the Vica faba growth as; the fresh dry weight of root and shoot, shoot length and stem diameter in soil invaded with F. oxysporum (T1), F. solani (T2) and R. Solani (T3) compared with controls. Treatments (T1, T2 and T3) showed that the disease index (DI) significantly differs from the positive controls (PC1, PC2 and PC3). This study recorded the success of Taguchi design to optimize conditions for maximum bacterial biomass and AgNPs synthesis from Bacillus amyloliquefaciens MH046937. AgNPs showed significant in-vivo effects against phytopathogens and received considerable attention as nanobiofungicide instead of hazardous chemical fungicides.