**Biosynthesis of Silver Nanoparticles Using Onion Endophytic Bacterium and Its Antifungal Activity against Rice Pathogen** *Magnaporthe oryzae*

#### **Ezzeldin Ibrahim 1,2, Jinyan Luo <sup>3</sup> , Temoor Ahmed <sup>1</sup> , Wenge Wu <sup>4</sup> , Chenqi Yan 5,\* and Bin Li 1,\***


Received: 30 September 2020; Accepted: 14 November 2020; Published: 18 November 2020 -

**Abstract:** Biosynthesis of silver nanoparticles (AgNPs) using endophytic bacteria is a safe alternative to the traditional chemical method. The purpose of this research is to biosynthesize AgNPs using endophytic bacterium *Bacillus endophyticus* strain H3 isolated from onion. The biosynthesized AgNPs with sizes from 4.17 to 26.9 nm were confirmed and characterized by various physicochemical techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), UV-visible spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) in addition to an energy dispersive spectrum (EDS) profile. The biosynthesized AgNPs at a concentration of 40 µg/mL had a strong antifungal activity against rice blast pathogen *Magnaporthe oryzae* with an inhibition rate of 88% in mycelial diameter. Moreover, the biosynthesized AgNPs significantly inhibited spore germination and appressorium formation of *M. oryzae*. Additionally, microscopic observation showed that mycelia morphology was swollen and abnormal when dealing with AgNPs. Overall, the current study revealed that AgNPs could protect rice plants against fungal infections.

**Keywords:** endophytic bacteria; silver nanoparticles; *Magnaporthe oryzae*; antifungal activity
