Extracellular biosynthesis and antimicrobial activity of Bacillus subtilis ATCC 6633 zinc oxide nanoparticles

Abstract

Recently, zinc oxide nanoparticles (ZnO NPs) have been used in several biological and industrial applications due to their low toxicity, high efficiency, biocompatibility, and cost-effectiveness. The present study used Bacillus subtilis ATCC 6633 in the biosynthesis of the antimicrobial ZnO NPs. The synthesized ZnO NPs were characterized using UV-Visible spectroscopy, Fourier transform-infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, Zeta potential analysis, and transmission electron microscopy (TEM). The TEM results confirmed the spherical shape of ZnO NPs with a size range of 13.5-30.4 nm. Zeta potential analysis showed the positive charge of ZnO NPs (+16.8 mV). The ZnO NPs showed good antimicrobial activity against the tested pathogenic bacterial strains; B. cereus (Gram-positive bacteria) in comparison to Escherichia coli (Gram-negative bacteria). They also revealed a high antifungal activity against the tested pathogenic fungal strain; Aspergillus niger. Here, this cost-effective and simple biological approach for ZnO NPs synthesis has emerged with a promising capacity in biomedicine, especially in the fields of antibacterial and antifungal fields.