The aim of this study was to isolate and characterize marine bacterial strains capable of converting selenite to elemental selenium with the formation of Se nanoparticles (SeNPs). For the first time, a novel marine strain belonging to Bacillus amyloliquefaciens (GenBank accession no. MK392020) was isolated from the coast of the Caspian Sea and characterized based on its ability for transformation of selenite to SeNPs under aerobic conditions. The preliminary formation of SeNPs was confirmed via color changes and the products characterized by UV–Vis spectroscopy. The field-emission scanning electron microscopy (FESEM) together with energy-dispersive X-ray (EDX) analysis showed the presence of the spherical SeNPs on both the surface of the bacterial biomass and in the supernatant solution. Dynamic light scattering (DLS) analysis showed the SeNPs to have an average particle size (Z-average) around 45.4–68.3 nm. The X-ray diffraction (XRD) studies substantiated the amorphous nature of the biosynthesized SeNPs. Fourier-transform infrared spectroscopic (FTIR) studies of the SeNPs indicated typical proteinaceous and lipid-related bands as capping agents on the SeNPs. Different effective parameters corresponding the yield of SeNPs by B. amyloliquefaciens strain SRB04 were optimized under resting cell strategy. Results showed that the optimal process conditions for SeNP production were 2 mM of selenite oxyanion, 20 g/L of cell biomass, and 60 h reaction time. The synthesized SeNPs had a remarkable antibacterial activity on Staphylococcus aureus compared with chloramphenicol as a broad-spectrum antibiotic.

本研究的目的是分离和表征能够将亚硒酸盐转化为元素硒并形成硒纳米颗粒 (SeNPs) 的海洋细菌菌株。首次发现一种属于解淀粉芽孢杆菌的新型海洋菌株(GenBank 登录号 MK392020) 从里海沿岸分离出来，并根据其在有氧条件下将亚硒酸盐转化为 SeNP 的能力进行表征。SeNPs 的初步形成通过颜色变化和紫外-可见光谱表征的产物得到证实。场发射扫描电子显微镜 (FESEM) 和能量色散 X 射线 (EDX) 分析表明，细菌生物质表面和上清液中都存在球形 SeNP。动态光散射 (DLS) 分析显示 SeNP 的平均粒径（Z 均值）约为 45.4-68.3 nm。X 射线衍射 (XRD) 研究证实了无定形生物合成的 SeNP 的性质。SeNPs 的傅里叶变换红外光谱 (FTIR) 研究表明典型的蛋白质和脂质相关条带作为 SeNPs 的封端剂。在静息细胞策略下优化了与解淀粉芽孢杆菌菌株 SRB04产生的 SeNP 产量相对应的不同有效参数。结果表明，SeNP 生产的最佳工艺条件是 2 mM 亚硒酸盐氧阴离子、20 g/L 细胞生物量和 60 h 反应时间。与氯霉素作为广谱抗生素相比，合成的SeNPs对金黄色葡萄球菌具有显着的抗菌活性。