The use of microorganisms that allows the recovery of critical high-tech elements such as gallium (Ga) and indium (In) has been considered an excellent eco-strategy. In this perspective, it is relevant to understand the strategies of Ga and In resistant strains to cope with these critical metals. This study aimed to explore the effect of these metals on two Ga/In resistant strains and to scrutinize the biological processes behind the oxidative stress in response to exposure to these critical metals. Two strains of Serratia fonticola, A3242 and B2A1Ga1, with high resistance to Ga and In, were submitted to metal stress and their protein profiles showed an overexpressed Superoxide Dismutase (SOD) in presence of In. Results of inhibitor-protein native gel incubations identified the overexpressed enzyme as a Fe-SOD. Both strains exhibited a huge increase of oxidative stress when exposed to indium, visible by an extreme high amount of reactive oxygen species (ROS) production. The toxicity induced by indium triggered biological mechanisms of stress control namely, the decrease in reduced glutathione/total glutathione levels and an increase in the SOD activity. The effect of gallium in cells was not so boisterous, visible only by the decrease of reduced glutathione levels. Analysis of the cellular metabolic viability revealed that each strain was affected differently by the critical metals, which could be related to the distinct metal uptakes. Strain A3242 accumulated more Ga and In in comparison to strain B2A1Ga1, and showed lower metabolic activity. Understanding the biological response of the two metal resistant strains of S. fonticola to stress induced by Ga and In will tackle the current gap of information related with bacteria-critical metals interactions.

可以回收关键的高科技元素（例如镓（Ga）和铟（In））的微生物被认为是一种出色的生态策略。从这个角度来看，了解抗Ga和In的菌株应对这些关键金属的策略非常重要。这项研究旨在探讨这些金属对两种耐Ga / In的菌株的影响，并研究对暴露于这些关键金属后氧化应激背后的生物学过程。两种沙雷氏菌对Ga和In具有高抗性的A3242和B2A1Ga1受到金属胁迫，它们的蛋白质谱显示在In存在下过表达的超氧化物歧化酶（SOD）。抑制剂-蛋白质天然凝胶温育的结果确定了过表达的酶为Fe-SOD。当暴露于铟时，两种菌株均表现出氧化应激的极大增加，这可通过产生大量的活性氧（ROS）来看出。铟诱导的毒性触发了压力控制的生物学机制，即减少的谷胱甘肽/总谷胱甘肽水平降低和SOD活性增加。镓在细胞中的作用并不是那么剧烈，只有减少的谷胱甘肽水平降低才可见。细胞代谢活力的分析表明，每种菌株受关键金属的影响不同，这可能与不同的金属吸收有关。与菌株B2A1Ga1相比，菌株A3242积累了更多的Ga和In，并且代谢活性较低。了解两种金属抗性菌株的生物学反应S. fonticola对由Ga和In诱导的胁迫的解决将解决当前与细菌-关键金属相互作用有关的信息缺口。