Abstract
The scientific consensus is now on developing a biocontrol agent that can cause cellular metabolic reprogramming against agricultural pathogens. Biosynthesis of silver nanoparticles was performed by using phytopathogenic fungi (Alternaria sp.) isolated from banana cultivated soil. Alternaria sp. can grow very fast and produce high enough bioactive compounds. This study aims to biosynthesize silver nanoparticles (AgNPs) using fungal Alternaria sp.’s metabolites as a safe antifungal agent against plant pathogenic fungi (Fusarium spp. and Alternaria sp.). To visualize the formation of AgNPs, analytical instruments were used, such as ultraviolet-visible (UV-Vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, scanning transmission electron microscopy (STEM), energy dispersive X-ray (EDX), and elemental mapping. The UV-visible spectra showed a peak at 435 nm. Analysis of scanning transmission electron microscopy (STEM) micrographs evidenced that the size of synthesized silver nanoparticles ranged between 3 and 10 nm. The resulting AgNPs showed distinct antifungal activity against selected plant pathogenic fungi. Synthesized AgNPs have demonstrated remarkable potential for the use of antifungal compounds to combat plant diseases.
Highlights
Biological control agents should be prepared with less risk to human and livestock [1]
Presumptive identifications were confirmed with internal transcribed spacer (ITS) rDNA sequence analysis. e entire ITS region of the fungal isolates was amplified with the primer pair ITS1F (5′-CTTGGTCATTTAGAGGAAGTAA-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) [15]. e resulting amplicons were sequenced by a 3730 XL DNA analyser (Applied Biosystems, USA)
Optical property such as localized surface plasmon resonance (LSPR) for the AgNPs was identified by UVvisible spectrometry (Shimadzu UV3600, Japan). e reaction was terminated after SPR bands saturation. e acquired product in suspension was recovered by centrifugation at 12,000 rpm for 15 min. e collected AgNPs were repeatedly washed and freeze-dried. e fungimediated green synthesis of silver nanoparticles was further used for characterizing their properties and examining their antifungal activity against phytopathogens [17]
Summary
Biological control agents should be prepared with less risk to human and livestock [1]. Fungi can produce a considerable amount of extracellular enzymes such as chitinases, glucanases, proteases, glycosyl hydrolases, xylanases, cellulases, and mannanases under suitable conditions [5]. Because of their conformity with the ideals and concepts of green chemistry, metallic nanoparticles from biological sources have received a great deal of attention [6]. For the control of some plant fungal diseases, biogenic nanoparticles have proved to be effective nanomaterialbased fungicides. Synthesis of metal NPs based on fungal extract is found to be the most effective and environmentally-friendly way of preparing biocontrol agents for phytopathogens suppression
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