BIOSURFACTANT MEDIATED SYNTHESIS OF SILVER NANOPARTICLES USING LACTOBACILLUS BREVIS (MTCC 4463) AND THEIR ANTIMICROBIAL STUDIES

Biosurfactants are surface active, amphiphilic biochemical compounds containing both hydrophobic and hydrophilic moieties produced by microorganisms. They are produced by a variety of microorganisms mainly fungi, bacteria, and yeasts on their cell surface or extracellularly secreted. Biosurfactant mediated synthesis of nanoparticles has now emerged as a green alternative for enhancing both nanoparticles synthesis & stabilization. One of the modes of action is through adsorbing onto metallic nanoparticles, surface stabilizing the nanoparticles & preventing aggregation. Hence, biosurfactant mediated production of silver nanoparticles (AgNPs) was utilized in the present work. Biosurfactant was produced using Lactobacillus brevis and thus obtained biosurfactant was added to equal amounts of 1mM AgNO₃ for production of AgNPs. The primary characterization of the AgNPs was done by visual observation. Further, AgNPs were characterized using UV-Vis Spectrophotometer which showed maximum absorption spectra at 420 nm, TEM revealed the size of AgNPs (18 nm). EDS was carried out to determine the presence of silver metal.  Biosurfactant mediated AgNPs were assessed for the antimicrobial studies on MDR strains of bacteria and fungi (S. aureus and Candida sp.), of which S. aureus showed comparatively more susceptible. The synergistic effect of biosurfactant & AgNPs enhanced antimicrobial effects on the selected stains compared to the individual effects.