Biosynthesis, Characterization and Antimicrobial Activity of Silver Nanoparticles Using Cell Free Lysate of Bacillus Subtilis: A Biotechnology Approach

Abstract

Present study was aimed at the bio-synthesis and characterization of silver nanoparticles (AgNPs) using bacterial cell free lysate of Bacillus specie isolated from iron-rust contaminated soil sample from the Niger Delta region of Nigeria. This method was cost effective, eco-friendly and an alternative to chemical synthesis which is hazardous and requiring tedious synthetic manipulation. This study also evaluated the antimicrobial effect of the synthesized silver nanoparticles. Silver nanoparticles produced by reacting cell-free lysate of Bacillus subtilis and 1 mM of aqueous silver nitrate solution were characterized by Ultraviolet-visible spectroscopy, Transmission electron microscopy (TEM) and Photon correlation microscopy (Zeta sizer). The UV-Visible spectrophotometric result revealed an absorption maxima corresponding to peaks near 428 nm, depicting reduction of ionic silver (Ag+) to silver atom (Ag0). It has already been reported that nitrate reductase enzymes are implicated in metal ion reduction reactions. The Transmission electron microscopy analysis revealed that the AgNPs size ranged between 58.24 ± 1.04 nm and 72.20 ± 2.10 nm complementing the result obtained from Photon correlation microscopy (76.86 ± 1.14 nm). The antibacterial activity of AgNPs gave highest inhibition zone diameter of 26 mm on Pseudomonas aeruginosa at the dose of 0.10 mg/ml and 14 mm on tested Candida albicans. The synthesized silver nanoparticles were found to produce a dose dependent antimicrobial inhibitory effect while surface adsorption and lysis were implicated as the mode of action