A group of nanoparticles (NPs); ZnO, CuO, MgO, and Se were eco-friendly biosynthesized using gamma irradiated culture filtrate of Bacillus cereus. The impact of obtained NPs on growth and lipid accumulation of Chlorella vulgaris was evaluated. NPs were characterized by UV–Vis., FTIR, XRD, and TEM. After irradiation, an increase in NPs reduction and/or yield was observed and confirmed by UV. NPs demonstrated spherical morphology with crystal size; 12–105 nm indicated by XRD and TEM images. FTIR analysis of the bacterial filtrate suggested the presence of biomolecules which may act as reducing and stabilizing agents. Low concentrations of obtained NPs enhanced the biomass and lipid production of C. vulgaris with 50 mg/L of ZnONPs demonstrating the highest potential to enhance both of them. Saturated and polyunsaturated fatty acids contents of C. vulgaris increased by ~ 16% and ~ 59% respectively, while unsaturated FA content decreased by ~ 20% compared to control. In conclusion, this study highlights the efficiency of B. cereus filtrate on biosynthesis of different NPs. Moreover, coupling of biosynthesized NPs with gamma irradiation represents a potential strategy to increase NPs yield. Irradiated biosynthesized NPs could be used to enhance the production of microalgal biomass and lipids as a promising feedstock for several applications.

一组纳米粒子（NPs）；ZnO、CuO、MgO 和 Se 是使用蜡样芽孢杆菌的伽马辐射培养滤液进行环保生物合成的。评估了获得的 NPs 对小球藻生长和脂质积累的影响。纳米颗粒通过紫外-可见光、红外光谱、XRD 和 TEM 进行表征。辐照后，观察到 NPs 减少和/或产量增加，并通过 UV 确认。NPs 显示出具有晶体尺寸的球形形态；12-105 nm 由 XRD 和 TEM 图像指示。细菌滤液的 FTIR 分析表明存在可作为还原剂和稳定剂的生物分子。低浓度获得的 NPs 提高了C. vulgaris的生物量和脂质生产50 mg/L 的 ZnONPs 显示出增强它们的最大潜力。C. vulgaris 的饱和和多不饱和脂肪酸含量分别增加了 ~ 16% 和 ~ 59%，而与对照相比，不饱和脂肪酸含量减少了 ~ 20%。总之，本研究强调了蜡状芽孢杆菌滤液对不同 NP 生物合成的效率。此外，生物合成 NPs 与伽马辐射的耦合代表了增加 NPs 产量的潜在策略。辐照后的生物合成 NPs 可用于提高微藻生物质和脂质的生产，作为多种应用的有前途的原料。