Green synthesis of zinc oxide nanoparticles using Bacillus subtilis ZBP4 and their antibacterial potential against foodborne pathogens

Abstract

In this study, extracellular biosynthesis of zinc oxide nanoparticles (ZnO NPs) by using the supernatant of Bacillus subtilis ZBP4 after cultivation in nutrient broth at 33 °C for 24 h was investigated. Zinc sulfate heptahydrate was used as the precursor, and the reactions were performed at 33 °C for 72 h. The effects of pH 5–9 and precursor concentration (2–10 mM) were determined and the optima were found to be pH 7.5 and 8 mM ZnSO₄·7H₂O, respectively. The nanoparticles were characterized by UV-VIS spectroscopy, FESEM, TEM, EDS, XRD, FTIR and zeta potential measurement. ZnO NPs appeared to be irregular spherical structures with a size range of 22–59 nm, as confirmed by FESEM and TEM. Energy-dispersive spectroscopy analysis validated the formation of ZnO NPs. X-ray diffraction analysis revealed the crystalline structure of the ZnO NPs, and they were determined to have a zeta potential of −19.0 ± 4.3 mV and a bandgap of 3.36 eV. Antibacterial activity experiments showed that ZnO NPs are effective against a broad spectrum of Gram-positive and Gram-negative food pathogens. This study provides evidence for a safe and effective method for synthesizing ZnO NPs and demonstrates their effectiveness against pathogenic bacteria.

Keywords:

• Antibacterial activity
• Bacillus
• biosynthesis
• nanoparticles
• ZnO NPs

Acknowledgments

The authors thank Prof Dr. Ahmet Alp and Sezer Tan (Metallurgical and Materials Engineering Department/Sakarya University) for their kind help in the zeta potential analysis. The authors also acknowledge Fuat Kayıs (Metallurgical and Materials Engineering Department/Sakarya University) for his effort in XRD analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Ayşe Avcı designed the experiments, supervised all the research work and analysis, and prepared the manuscript. Mohammed Hamk participated in running all the experiments and preparing the draft manuscript. Fikriye Alev Akçay helped assist in certain aspects of the experiments. All authors read and approved the final manuscript.

Data availability statement

The datasets generated during and/or analyzed during the current study are not publicly available. Data are, however available from the corresponding author on reasonable request.

Additional information

Funding

Funding Author Mohammed Hamk has received research support from Presidency for Turks Abroad and Related Communities.