Akkaya Sefa Nur, Almansour Ammar, Omeroglu Mehmet Akif, Nadaroglu Hayrunnisa, Adiguzel Ahmet
Department of Molecular Biology and Genetics, Faculty of Science, Ataturk University, 25240 Erzurum, Turkey.
Department of Nanoscience and Nanoengineering, Graduate School of Natural and Applied Science, Atatürk University, 25240 Erzurum, Turkey.
FEMS Microbiol Lett. 2025 Jan 10;372. doi: 10.1093/femsle/fnaf036.
The preparation of silver nanoparticles (AgNPs) via an environmentally friendly green synthesis method represents an ecologically promising alternative. This research aims to develop sustainable and eco-friendly AgNPs using the lignin peroxidase (LiP) enzyme from Caldibacillus thermoamylovorans, cultivated on waste walnut shells, which are rich in lignin, to meet the growing demand for AgNPs. Among thermophilic bacteria that were isolated, the C. thermoamylovorans SA1 strain showed the highest LiP activity. The production of LiP was optimized by adding waste walnut shells and manipulating the environmental parameters. The optimal conditions were determined at 50 g/l shell amount, 96 h, pH 8, 140 rpm, and 60°C. In parallel with the increase in enzyme activity, bacterial growth also increased. As a result of the optimization, the highest enzyme activity value was 435.0 U/ml and bacterial growth was determined to be OD600: 2.09. The extracellular medium obtained from the bacteria grown in walnut shell medium was then added to an AgNO3 solution. Efficient production of AgNPs was achieved by stirring the mixture at 50°C-60°C for 4 h under optimum conditions. The synthesized AgNPs were characterized using a range of analytical techniques, including UV‒Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The biological efficacy of the synthesized AgNPs was evaluated by assessing their antibacterial activity against pathogenic bacteria, such as Escherichia coli O157:H7, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus pyogenes, and Bacillus cereus. The highest activity was observed against B. cereus (15 mm). The broad-spectrum antibacterial properties exhibited by the AgNPs synthesized in this study offer a promising and sustainable solution for diverse applications in various sectors, including the environmental, agricultural, medical, and pharmaceutical fields.
通过环境友好的绿色合成方法制备银纳米颗粒（AgNPs）是一种具有生态前景的替代方法。本研究旨在利用嗜热淀粉芽孢杆菌（Caldibacillus thermoamylovorans）的木质素过氧化物酶（LiP），在富含木质素的废弃核桃壳上培养该菌，以开发可持续且环保的AgNPs，满足对AgNPs不断增长的需求。在所分离的嗜热细菌中，嗜热淀粉芽孢杆菌SA1菌株显示出最高的LiP活性。通过添加废弃核桃壳并控制环境参数来优化LiP的产生。确定最佳条件为壳量50 g/l、96小时、pH 8、140 rpm和60°C。随着酶活性的增加，细菌生长也增加。优化的结果是，最高酶活性值为435.0 U/ml，细菌生长测定为OD600：2.09。然后将从在核桃壳培养基中生长的细菌获得的细胞外培养基添加到硝酸银溶液中。在最佳条件下，将混合物在50°C - 60°C搅拌4小时，实现了AgNPs的高效生产。使用一系列分析技术对合成的AgNPs进行表征，包括紫外可见光谱、傅里叶变换红外光谱、X射线衍射和扫描电子显微镜。通过评估合成的AgNPs对致病细菌如大肠杆菌O157:H7、肺炎克雷伯菌、金黄色葡萄球菌、化脓性链球菌和蜡样芽孢杆菌的抗菌活性来评价其生物学功效。观察到对蜡样芽孢杆菌的活性最高（15 mm）。本研究中合成的AgNPs所表现出的广谱抗菌特性为包括环境、农业、医学和制药领域在内的各个部门的各种应用提供了一种有前景的可持续解决方案。
