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.

摘要

在这项研究中，研究了使用枯草芽孢杆菌 ZBP4 在 33 °C 的营养肉汤中培养 24 小时后的上清液的细胞外生物合成氧化锌纳米颗粒 (ZnO NPs)。以七水硫酸锌为前驱体，反应在33℃下进行72小时。确定了 pH 5–9 和前体浓度 (2–10 mM) 的影响，发现最佳值为 pH 7.5 和 8 mM ZnSO ₄ ·7H ₂分别哦。通过紫外-可见光谱、FESEM、TEM、EDS、XRD、FTIR 和 zeta 电位测量对纳米粒子进行了表征。正如 FESEM 和 TEM 所证实的，ZnO NP 似乎是不规则的球形结构，尺寸范围为 22-59 nm。能量色散光谱分析验证了 ZnO NPs 的形成。X 射线衍射分析揭示了 ZnO NP 的晶体结构，并确定它们具有 -19.0 ± 4.3 mV 的 zeta 电位和 3.36 eV 的带隙。抗菌活性实验表明，ZnO NPs 对广谱革兰氏阳性和革兰氏阴性食品病原体有效。该研究为合成 ZnO NPs 的安全有效方法提供了证据，并证明了它们对致病菌的有效性。