Caldeira Joana B, Chung Ana Paula, Morais Paula V, Branco Rita
Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal.
Appl Microbiol Biotechnol. 2021 Apr;105(8):3301-3314. doi: 10.1007/s00253-021-11254-6. Epub 2021 Apr 1.
Aluminium (Al), gallium (Ga), and indium (In) are metals widely used in diverse applications in industry, which consequently result in a source of environmental contamination. In this study, strain Rhodanobacter sp. B2A1Ga4, highly resistant to Al, Ga, and In, was studied to reveal the main effects of these metals on the strain and the bacterial mechanisms linked to the ability to cope with them. An indium-sensitive mutant obtained by random transposon mutagenesis has the feoA gene interrupted. This gene together with the feoB gene is part of the feo operon which encodes a ferrous uptake system (FeoAB). The mutant strain exhibited higher oxidative stress supported by a high concentration of reactive oxygen species (ROS) and low levels of reduced glutathione (GSH) in the presence of metals. The iron supplementation of the growth medium reverted the growth inhibition of the mutant strain caused by Ga and In, significantly reduced the ROS amounts in mutant cells grown in all conditions, and increased its GSH/total glutathione ratio to values similar to those of the native strain. Moreover, the mutant strain when submitted to In increased the production of siderophores. The genome sequence analysis of strain B2A1Ga4 showed a large number of genes encoding putative proteins involved in iron uptake from the cell surface to the cytoplasm. Understanding the bacteria-metal interactions linked to resistance to high-tech metals is relevant to future application of microorganisms in bioremediation and/or biorecovery processes of these metals. KEY POINTS: • The disruption of FeoAB system compromises the bacterial resistance to Al, Ga, and In. • The iron acquisition in Rhodanobacter sp. B2A1Ga4 controls the oxidative stress. • Genome mining of strain B2A1Ga4 reveals several iron transport related genes.
铝（Al）、镓（Ga）和铟（In）是广泛应用于工业各种领域的金属，因此成为环境污染的一个来源。在本研究中，对高度耐铝、镓和铟的菌株红环菌属（Rhodanobacter sp.）B2A1Ga4进行了研究，以揭示这些金属对该菌株的主要影响以及与应对这些金属能力相关的细菌机制。通过随机转座子诱变获得的对铟敏感的突变体，其feoA基因被中断。该基因与feoB基因一起是feo操纵子的一部分，该操纵子编码一个亚铁摄取系统（FeoAB）。在金属存在的情况下，突变菌株表现出更高的氧化应激，表现为活性氧（ROS）浓度高和还原型谷胱甘肽（GSH）水平低。在生长培养基中补充铁可逆转由镓和铟引起的突变菌株的生长抑制，显著降低在所有条件下生长的突变细胞中的ROS量，并将其GSH/总谷胱甘肽比率提高到与野生型菌株相似的值。此外，突变菌株在接触铟时会增加铁载体的产生。菌株B2A1Ga4的基因组序列分析显示，有大量基因编码与从细胞表面到细胞质摄取铁有关的假定蛋白质。了解与对高科技金属抗性相关的细菌 - 金属相互作用对于微生物在这些金属的生物修复和/或生物回收过程中的未来应用具有重要意义。要点：• FeoAB系统的破坏损害了细菌对铝、镓和铟的抗性。• 红环菌属（Rhodanobacter sp.）B2A1Ga4中的铁获取控制氧化应激。• 菌株B2A1Ga4的基因组挖掘揭示了几个与铁运输相关的基因。
