Zhejiang Provincial Key Laboratory for Technology and Application of Model Organisms, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, P.R. China.
School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, Zhejiang, P.R. China.
J Microbiol Biotechnol. 2020 Jul 28;30(7):996-1004. doi: 10.4014/jmb.1912.12030.
Various genetically engineered microorganisms have been developed for the removal of heavy metal contaminants. Metal biosorption by whole-cell biosorbents can be enhanced by overproduction of metal-binding proteins/peptides in the cytoplasm or on the cell surface. However, few studies have compared the biosorption capacity of whole cells expressing intracellular or surface-displayed metal-adsorbing proteins. In this study, several constructs were prepared for expressing intracellular and surface-displayed 5bvl1 ChrB in BL21(DE3) cells. cells expressing surface-displayed ChrB removed more Cr(VI) from aqueous solutions than cells with cytoplasmic ChrB under the same conditions. However, intracellular ChrB was less susceptible to variation in extracellular conditions (pH and ionic strength), and more effectively removed Cr(VI) from industrial wastewater than the surface-displayed ChrB at low pH (<3). An adsorptiondesorption experiment demonstrated that compared with intracellular accumulation, cell-surface adsorption is reversible, which allows easy desorption of the adsorbed metal ions and regeneration of the bioadsorbent. In addition, an intrinsic ChrB protein fluorescence assay suggested that pH and salinity may influence the Cr(VI) adsorption capacity of ChrB-expressing cells by modulating the ChrB protein conformation. Although the characteristics of ChrB may not be universal for all metal-binding proteins, our study provides new insights into different engineering strategies for whole-cell biosorbents for removing heavy metals from industrial effluents.
已经开发出各种基因工程微生物来去除重金属污染物。通过在细胞质或细胞表面过表达金属结合蛋白/肽，可以增强全细胞生物吸附剂对金属的吸附能力。然而，很少有研究比较过表达细胞内或表面展示金属吸附蛋白的全细胞的吸附能力。在这项研究中，我们制备了几种表达细胞内和表面展示的 5bvl1 ChrB 的构建体在 BL21(DE3)细胞中。在相同条件下，表达表面展示 ChrB 的细胞从水溶液中去除的 Cr(VI)比细胞质 ChrB 多。然而，细胞内 ChrB 对外界条件（pH 值和离子强度）的变化不太敏感，并且在低 pH 值（<3）下，它比表面展示 ChrB 更有效地从工业废水中去除 Cr(VI)。吸附-解吸实验表明，与细胞内积累相比，细胞表面吸附是可逆的，这允许容易解吸吸附的金属离子并使生物吸附剂再生。此外，内在 ChrB 蛋白荧光测定表明，pH 值和盐度可能通过调节 ChrB 蛋白构象来影响表达 ChrB 的细胞对 Cr(VI)的吸附能力。尽管 ChrB 的特性可能不适用于所有金属结合蛋白，但我们的研究为从工业废水中去除重金属的全细胞生物吸附剂的不同工程策略提供了新的见解。
