Abstract Industrial activities discharge a large amount of wastes containing hexavalent chromium [Cr(VI)] into the environment, which poses a threat to human health. Microorganisms can be used as efficient tools for Cr(VI) remediation. In this study, the Cr(VI) removal capacity of Aspergillus niger was evaluated. A. niger could tolerate and reduce Cr(VI) by nearly 100% at concentrations ranging from 10 to 50 mg/L. Overall, almost 97% of the Cr(VI) removal was caused by extracellular reduction whereas 3% was caused by accumulation. Extracellular reduction was mediated by non-enzymatic cell secretions, whereas extracellular accumulated Cr formed precipitates on the hyphal surfaces and was partially absorbed on the cell wall. Cr(VI) also entered the cell and was reduced by the strong chromate reductase activity in cell-free extracts and then accumulated within the cell. These data suggest that A. niger, which has the capacity to remove Cr(VI) by reduction and accumulation, can be a useful tool for Cr(VI) remediation.

中文翻译：

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黑曲霉还原积累去除六价铬

摘要 工业活动向环境中排放了大量含有六价铬[Cr(VI)]的废物，对人类健康构成威胁。微生物可用作 Cr(VI) 修复的有效工具。在这项研究中，评估了黑曲霉的 Cr(VI) 去除能力。A. niger 可以在 10 到 50 mg/L 的浓度范围内耐受和减少近 100% 的 Cr(VI)。总体而言，几乎 97% 的 Cr(VI) 去除是由细胞外还原引起的，而 3% 是由积累引起的。细胞外还原是由非酶促细胞分泌物介导的，而细胞外积累的 Cr 在菌丝表面形成沉淀并部分吸收在细胞壁上。Cr(VI) 也进入细胞并被无细胞提取物中强烈的铬酸还原酶活性还原，然后在细胞内积累。这些数据表明，能够通过还原和积累去除 Cr(VI) 的 A. niger 可以成为修复 Cr(VI) 的有用工具。