S. Krishnakumar and  V. Dooslin Mercy Bai

ABSTRACT

Plant pathogens cause many serious diseases to plants across the world and cause tremendous crop damage leads to economic loss to the farmers. Most of the plants possess disease resistance to many pathogens. However, some plants can harbor plant pathogens without any symptom development and reduce the crop yield drastically. In the present study we have isolated antagonistic actinomycetes from terrestrial red garden soil. The potential isolate was identified as Streptomyces sp.-SBU3 and used for extracellular synthesis of silver nanoparticles (Ag-NPs). The cell free culture supernatant was used for the synthesis of Ag-NPs by using 1mM silver nitrate (AgNO3) solution. The colour of the reaction mixture was changed from pale to brown indicates the synthesis of silver nanoparticles. Silver nanoparticles were further confirmed by performing thin layer chromatography (TLC). A single separate band of silver nanoparticle was observed with the Rf value of 0.70. Silver nanoparticles have been known to have antimicrobial effects that can be used to control the plant disease. The synthesized Ag-NPs were evaluated for their antimicrobial activity against selected plant pathogens, which showed maximum activity against bacteria when compared to fungal pathogens. Silver nanoparticle synthesized using terrestrial Streptomyces sp.-SBU3 is a promising source of cost effective and eco-friendly antimicrobial agent for the management of plant diseases. Key words: silver nanoparticles, antimicrobial activity, plant pathogens, Streptomyces sp.