Mycogenic Silver Nanoparticles Synthesized by Trichoderma reesei: Physicochemical Characterization and Antibacterial Activity Against Ralstonia solanacearum

Abstract

Background: Bacterial wilt (Bw) is one of the most important constraints in tomato production and is caused by the bacterium Ralstonia solanacearum. Green synthesis of silver nanoparticles (AgNPs) using fungal metabolites is an eco-friendly approach to alternative methods of chemical synthesis.
Objectives: Objective of the study was synthesis and characterization of AgNPs by cell-free filtrate of Trichoderma reesei and the evaluation of the antibacterial activity against the bacterium R. solanacearum.
Methods: Morphological and ITS rDNA were used to identify Trichoderma reesei (PX585131), isolated from the tomato rhizosphere soil. Its cell-free filtrate was used for the synthesis of AgNPs which was characterized by UV–Vis, FTIR, TEM, DLS and zeta potential analysis. The antibacterial activity was assessed by disc diffusion and broth inhibition method.
Results: The presence of AgNPs was confirmed based on the colour change and SPR band. TEM showed predominately spherical shaped nanoparticles with diameter range of 8–50 nm, whereas DLS micrograph showed hydrodynamic diameter of 191.9 nm (PDI 0.307) and zeta potential of −15.8 mV. FTIR suggested that proteins and polysaccharides are responsible for the capping of nanoparticles. The synthesized AgNPs were found to possess antibacterial activity against R. solanacearum.
Conclusion: The AgNPs were synthesized using green synthesis using cell-free filtrate of Trichoderma reesei with the desired physicochemical properties and antibacterial activity against R. solanacearum.