Detoxification of heavy metal pollutants in wastewater has become a serious problem to surrounding environment. This research was conducted to utilize a potential heavy metal-resistant bacterium for the remediation of cobalt metal and simultaneous synthesis of cobalt oxide nanoparticles in the form of powder for various industrial applications. Metal oxide nanoparticles have great applications in electrochemical devices such as supercapacitors, biosensors, and batteries. A heavy metal-resistant bacterium Microbacterium sp. MRS-1 isolated from electroplating industrial effluent reduced cobalt ions from an initial concentration of 200 mg/L to 26 mg/L were analyzed by atomic absorption spectroscopy. Instrumental analysis of bacterially synthesized Co3O4 has been characterized. Cytotoxicity of synthesized nanoparticles was assessed by MTT assay. Microbacterium sp. MRS-1 isolated from electroplating industrial effluent was found to be suitable for cobalt oxide nanoparticles as it showed tolerance towards high concentration of metal. The nutrient broth containing metal solution and Microbacterium sp. MRS-1 showed color change from light pink to dark pink indicated the formation of extracellular nanoparticles. It also converted soluble cobalt salts into less soluble cobalt oxide nanoparticles outside the cell which allows easy recovery of nanoparticles without the destruction of cells and simultaneous detoxification of toxic metal ions. Electron microscopic imaging verified that nanoparticles were predominantly surrounding the bacterial cells and SEM imaging revealed that the produced particles were in the range of 10–100 nm in size. XRD spectrum exhibited 2θ values were corresponding to cubic face-centered cobalt oxide (Co3O4) nanoparticles. The present study investigated new prospective for eco-friendly detoxification of toxic heavy metal Co from metal-polluted sites and the production of cobalt oxide nanoparticles in powder form for clinical and other industrial applications.

中文翻译：

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微杆菌属 MRS-1，一种用于钴还原和合成低毒/无毒氧化钴纳米粒子 (Co3O4) 的潜在细菌

废水中重金属污染物的脱毒已成为对周围环境造成严重影响的问题。进行这项研究是为了利用一种潜在的抗重金属细菌来修复钴金属并同时合成粉末形式的氧化钴纳米颗粒，用于各种工业应用。金属氧化物纳米粒子在超级电容器、生物传感器和电池等电化学装置中有着广泛的应用。一种重金属抗性细菌 Microbacterium sp. 通过原子吸收光谱分析从电镀工业废水中分离出的 MRS-1 将钴离子从初始浓度 200 mg/L 还原到 26 mg/L。已对细菌合成的 Co3O4 进行仪器分析。合成的纳米颗粒的细胞毒性通过 MTT 测定进行评估。微杆菌属 发现从电镀工业废水中分离出的 MRS-1 适用于氧化钴纳米粒子，因为它对高浓度金属表现出耐受性。含有金属溶液和微杆菌属的营养肉汤。MRS-1 显示颜色从浅粉红色变为深粉红色，表明细胞外纳米颗粒的形成。它还在细胞外将可溶性钴盐转化为溶解性较低的氧化钴纳米颗粒，从而可以轻松回收纳米颗粒，而不会破坏细胞并同时解毒有毒金属离子。电子显微成像证实纳米粒子主要围绕细菌细胞，SEM 成像显示产生的粒子大小在 10-100 nm 范围内。XRD 谱显示的 2θ 值对应于立方面心氧化钴 (Co3O4) 纳米颗粒。本研究调查了从金属污染地点对有毒重金属 Co 进行生态友好解毒的新前景，以及用于临床和其他工业应用的粉末状氧化钴纳米颗粒的生产。