School of Urban Construction, Wuhan University of Science and Technology, Wuhan, Hubei, China.
Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China.
Biotechnol Bioeng. 2023 May;120(5):1334-1345. doi: 10.1002/bit.28350. Epub 2023 Feb 23.
Hexavalent chromium [Cr(Ⅵ)] is a highly toxic contaminant in aquatic systems, and microalgae represent promising bioremediators of metal-containing wastewater. However, the metal-binding capacity of algal cells is limited. Therefore, we improved the cellular Cr(Ⅵ) biosorption capacity of Chlamydomonas reinhardtii by overexpressing the sulfate transporter gene SULTR2. SULTR2 was predominantly located in the cytoplasm of the cell, and few proteins mobilized to the cell membrane as a Cr transporter under Cr stress conditions. Intracellular Cr accumulation was almost doubled in SULTR2-overexpressing transgenic strains after exposure to 30 μM K Cr O for 4 d. Alginate-based immobilization increased the rate of Cr removal from 43.81% to 88.15% for SULTR2-overexpressing transgenic strains after exposure to 10 μM K Cr O for 6 d. The immobilized cells also displayed a significant increase in nutrient removal efficiency compared to that of free-swimming cells. Therefore, SULTR2 overexpression in algae has a great potential for the bioremediation of Cr(Ⅵ)-containing wastewater.
六价铬（Cr(Ⅵ)）是水生系统中一种剧毒污染物，微藻是一种很有前途的含金属废水生物修复剂。然而，藻类细胞的金属结合能力是有限的。因此，我们通过过表达硫酸盐转运蛋白基因 SULTR2 来提高莱茵衣藻的细胞 Cr(Ⅵ)生物吸附能力。SULTR2 主要位于细胞的细胞质中，在 Cr 胁迫条件下，很少有蛋白质作为 Cr 转运蛋白向细胞膜转移。在暴露于 30 μM K Cr O 4 天后，SULTR2 过表达转基因株系的细胞内 Cr 积累几乎增加了一倍。在暴露于 10 μM K Cr O 6 天后，用海藻酸钠固定化 SULTR2 过表达转基因株系后，Cr 的去除率从 43.81%提高到 88.15%。与自由游动细胞相比，固定化细胞的营养物质去除效率也显著提高。因此，藻类中 SULTR2 的过表达对于含 Cr(Ⅵ)废水的生物修复具有巨大的潜力。
