A Novel Bacterial Route to Synthesize Cu Nanoparticles and Their Antibacterial Activity

This report focuses on a facile and one-pot way to synthesize stable Cu nanoparticles (NPs) through a bacterial approach using an inexpensive and non-toxic copper salt in the aqueous solution. Copper NPs were obtained from an extracellular enzymatic metal-reduction process via bacterial strains PN14F and B3 which were similar with Bacillus haynesii (99.87%) and Bacillus halotolerans (100%), respectively, on the basis of phylogenic analysis. It was found that Cu NPs were formed in the cell-free culture liquid but not in the fresh biomass medium, so that it was hypothesized that an extracellular compound was responsible for the proceeding. According to the spectroscopic data, the NPs can bind to the proteins through their free amine or carboxylate groups. It is noteworthy that by varying the bacterial supernatant, the remarkable changes occur in the size and morphology of copper NPs, where their thickness and diameter are observed to be 2–30 and 1–15 nm in the presence of bacterial strains PN14F and B3, respectively. It is noticeable that this manner is a novel, green, eco-friendly and suitable method for large-scale production. Finally, the as-made Cu NPs showed antibacterial activity against B. Subtilis, in which a significant decrease was observed in its growth.