Selenium (Se) is a nonmetallic element of the chalcogens. It is primarily available in natural environments as selenate and selenite oxoanions. Although selenate/selenite reduction in many microbes is widely studied at low concentrations (<50 mM), the effects of high selenate stress on bacterial growth, morphology, and cell components have not yet been studied. In this study, the response of Herbaspirillum sp. WT00C to selenate stress at high concentration is investigated by microbiological and scanning electron microscopy (SEM) techniques as well as proteomic analysis. Bacterial growth was seriously inhibited under high selenate concentrations and its growth‐inhibitory phase was prolonged with the increase of selenate concentrations. More interestingly, this bacterium was able to recover its growth even if the selenate concentration was up to 400 mM. Its growth inhibition period shortened to 6 h when the bacterium growing in 200 mM selenate for 28 h was reinoculated to the Luria‐Bertani medium containing 200 mM selenate. The high concentration of selenate also induces marked changes in the cell dimension and surface roughness, as revealed by SEM, along with compositional changes in the cell wall shown by proteomic analysis. The bacterial growth inhibition results from the marked downregulation of the α‐subunit of DNA polymerase III and RNA helicase, whereas its growth recovery is related to its high antioxidative activities. More NADPH synthesis and the upregulation of thioredoxin reductase and GPx are beneficial for Herbaspirillum sp. WT00C to establish and maintain a balance between oxidant and antioxidant intracellular systems for defending selenate toxicity. This study is an important contribution to understanding why Herbaspirillum sp. WT00C survives in a high concentration of selenate and how the bacterial cells respond physiologically to selenate stress at high concentration.

中文翻译：

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Herbaspirillum sp. 中的细菌生长、形态和细胞成分变化。WT00C 暴露于高浓度的硒酸盐

硒 (Se) 是硫属元素的非金属元素。它主要以硒酸盐和亚硒酸盐氧阴离子的形式存在于自然环境中。尽管在低浓度 (<50 mM) 下对许多微生物中的硒酸盐/亚硒酸盐还原进行了广泛研究，但尚未研究高硒酸盐胁迫对细菌生长、形态和细胞成分的影响。在这项研究中，Herbaspirillum sp. 的反应。通过微生物学和扫描电子显微镜 (SEM) 技术以及蛋白质组学分析研究了 WT00C 在高浓度下硒化应力。高硒酸盐浓度下细菌生长受到严重抑制，其生长抑制期随着硒酸盐浓度的增加而延长。更有趣的是，即使硒酸盐浓度高达 400 mM，这种细菌也能恢复生长。将在 200 mM 硒酸盐中生长 28 小时的细菌重新接种到含有 200 mM 硒酸盐的 Luria-Bertani 培养基中，其生长抑制期缩短至 6 小时。SEM 显示，高浓度的硒酸盐还会引起细胞尺寸和表面粗糙度的显着变化，以及蛋白质组学分析显示的细胞壁成分变化。细菌生长抑制是由于 DNA 聚合酶 III 和 RNA 解旋酶的 α 亚基显着下调，而其生长恢复与其高抗氧化活性有关。更多的 NADPH 合成和硫氧还蛋白还原酶和 GPx 的上调有利于草螺菌属。WT00C 建立和维持氧化剂和抗氧化剂细胞内系统之间的平衡，以防御硒酸盐毒性。这项研究是理解 Herbaspirillum sp. 的重要贡献。WT00C 在高浓度的硒酸盐中存活，以及细菌细胞如何在高浓度下对硒酸盐胁迫做出生理反应。