Serious hexavalent chromium [Cr(VI)] pollution has continuously threatened ecological security and public health. Microorganism-assisted remediation technology has strong potential in the treatment of environmental Cr(VI) pollution due to its advantages of high efficiency, low cost, and low secondary pollution. Sporosarcina saromensis M52, a strain with strong Cr(VI) removal ability, isolated from coastal intertidal zone was used in this study. Scanning electron microscopy coupled with energy dispersive X-ray analysis indicated M52 was relatively stable under Cr(VI) stress and trace amount of Cr deposited on the cell surface. X-ray photoelectron spectroscopy and X-ray diffraction analyses exhibited M52 could reduce Cr(VI) into Cr(III). Fourier transform infrared spectroscopy showed the bacterial surface was mainly consisted of polysaccharides, phosphate groups, carboxyl groups, amide II (NH/CN) groups, alkyl groups, and hydroxyl groups, while functional groups involving in Cr(VI) bio-reduction were not detected. According to these characterization analyses, the removal of Cr(VI) was primarily depended on bio-reduction, instead of bio-adsorption by M52. Genome analyses further indicated the probable mechanisms of bio-reduction, including the active efflux of Cr(VI) by chromate transporter ChrA, enzymatic redox reactions mediated by reductases, DNA-repaired proteases ability to minimize the ROS damage, and the formation of specific cell components to minimize the biofilm injuries caused by Cr(VI). These studies provided a theoretical basis which was useful for Cr(VI) remediation, especially in terms of increasing its effectiveness.

The main finding of the work

M52 realized the bioremediation of Cr(VI) majorly through bio-reduction, including Cr(VI) efflux, chromate reduction, DNA repair, and the formation of specific cell components, instead of bio-adsorption.

中文翻译：

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从基因组角度探索 Sporosarcina saromensis M52 的 Cr(VI) 去除机制

严重的六价铬[Cr(VI)]污染持续威胁着生态安全和公众健康。微生物辅助修复技术由于具有高效、低成本、二次污染少等优点，在环境Cr(VI)污染的治理中具有强大的潜力。沙罗门孢子藻本研究使用从沿海潮间带分离的 M52 菌株，该菌株具有很强的 Cr(VI) 去除能力。扫描电子显微镜结合能量色散 X 射线分析表明 M52 在 Cr(VI) 应力和痕量 Cr 沉积在细胞表面下相对稳定。X 射线光电子能谱和 X 射线衍射分析表明 M52 可以将 Cr(VI) 还原为 Cr(III)。傅里叶变换红外光谱显示细菌表面主要由多糖、磷酸基、羧基、酰胺II(NH/CN)基、烷基和羟基组成，而参与Cr(VI)生物还原的官能团则不存在。检测到。根据这些表征分析，Cr(VI) 的去除主要取决于生物还原，而不是 M52 的生物吸附。基因组分析进一步表明了生物还原的可能机制，包括铬酸盐转运蛋白 ChrA 主动流出 Cr(VI)、还原酶介导的酶促氧化还原反应、DNA 修复蛋白酶将 ROS 损伤降至最低的能力，以及特定细胞的形成以尽量减少由 Cr(VI) 引起的生物膜损伤。这些研究为 Cr(VI) 的修复提供了理论基础，特别是在提高其有效性方面。

工作的主要发现

M52主要通过生物还原实现Cr(VI)的生物修复，包括Cr(VI)外排、铬酸盐还原、DNA修复和特定细胞成分的形成，而不是生物吸附。