Biosynthesis of silver nanoparticles by Variovorax guangxiensis THG-SQL3 and their antimicrobial potential

The present study described biosynthesis of silver nanoparticles (AgNPs) using a bacterial strain Variovorax guangxiensis THG-SQL3, isolated from soil, and their application in antibacterial activity. The synthesized AgNPs were characterized by several instrumental techniques, showed maximum absorbance at 418 nm and were mostly irregular spherical in shape with particle size in range of 10-40 nm. The synthesized AgNPs exhibited antimicrobial activity against various pathogens including Staphylococcus aureus, Vibrio parahaemolyticus, Candida albicans, Candida tropicalis, Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Bacillus cereus. In addition, the AgNPs in combination with commercial antibiotics enhanced antimicrobial activity against P. aeruginosa, Salmonella enterica, E. coli and V. parahaemolyticus. The AgNPs synthesized by strain V. guangxiensis THG-SQL3 are comparatively simple, green, cost-effective and may serve as a potential antimicrobial agent.