During bioleaching of Cobalt from waste lithium-ion batteries, the biooxidation activity of acidophilic bacteria is inhibited by a high concentration of Co ion in the liquid phase. However, the mechanism for Co²⁺ toxicity to acidophilic bacteria has not been fully elucidated. In this study, the effects of Co²⁺ concentration on the biooxidation activity for Fe²⁺, intracellular reactive oxygen species (ROS) level and antioxidant defense systems in a mixed-culture of acidophilic bacteria (MCAB) were investigated. The results showed that the biooxidation activity of the MCAB was inhibited by Co²⁺. Furthermore, it was indicated that the intracellular ROS contents of the MCAB under conditions of 0.4 M and 0.6 M Co²⁺ were 2.60 and 3.34 times higher than that under the condition of 0 M Co²⁺. The increase in intracellular malondialdehyde content indicated that the oxidative damage was induced by Co²⁺. Moreover, the antioxidant systems in MCAB were affected by Co²⁺. It was observed that the Co²⁺ exposure increased the catalase and glutathione peroxidase activities while reducing the superoxide dismutase activity and the intracellular glutathione (GSH) content. It was found that an exogenous GSH supplementation eliminated excess intracellular ROS and improved the biooxidation activity of the MCAB.

中文翻译：

---

嗜酸性细菌的混合培养物对Co2 +暴露的氧化应激和抗氧化防御特性。

从废锂离子电池中生物浸出钴过程中，液相中高浓度的Co离子抑制了嗜酸细菌的生物氧化活性。然而，尚未完全阐明Co ²⁺对嗜酸细菌的毒性机理。在这项研究中，研究了Co ²⁺浓度对嗜酸细菌（MCAB）混合培养中Fe ²⁺的生物氧化活性，细胞内活性氧（ROS）水平和抗氧化防御系统的影响。结果表明，Co ²⁺抑制了MCAB的生物氧化活性。此外，表明在0.4 M和0.6 M Co ^2+的条件下MCAB的细胞内ROS含量在0 M Co ²⁺的条件下分别是其的2.60和3.34倍。细胞内丙二醛含量的增加表明Co ²⁺诱导了氧化损伤。此外，MCAB中的抗氧化剂系统受Co ^2+的影响。观察到Co ²⁺暴露增加了过氧化氢酶和谷胱甘肽过氧化物酶活性，同时降低了超氧化物歧化酶活性和细胞内谷胱甘肽（GSH）含量。发现外源性GSH补充消除了过量的细胞内ROS并改善了MCAB的生物氧化活性。