College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China; Beijing Key Laboratory of Biodiversity and Organic Farming, China Agricultural University, Beijing 100193, China.
Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, CAS-HKU Joint Laboratory of Metallomics on Health & Environment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
J Hazard Mater. 2021 Jul 15;414:125545. doi: 10.1016/j.jhazmat.2021.125545. Epub 2021 Feb 26.
Microorganisms play a critical role in the reduction of the more toxic selenite and selenate to the less toxic elemental selenium. However, the assembly process and stability of selenium nanoparticles (SeNPs) remain understudied. The plant growth-promoting rhizobacterium Rahnella aquatilis HX2 can reduce selenite to biogenic SeNPs (BioSeNPs). Two main proteins, namely flagellin FliC and porin OmpF were identified in the BioSeNPs. The fliC and ompF gene mutation experiments demonstrated that the FliC and OmpF could control the assembly of BioSeNPs in vivo. At the same time, the expressed and purified FliC and OmpF could control the assembly of SeNPs in vitro. BioSeNPs produced by R. aquatilis HX2 exhibited high stability under various ionic strengths, while the chemically synthesized SeNPs (CheSeNPs) showed a high level of aggregation. The in vitro experiments verified that FliC and OmpF could prevent the aggregation of the CheSeNPs under various ionic strengths. This work reports the preparation of highly stable BioSeNPs produced by strain R. aquatilis HX2 and verifies that FliC and OmpF both could control the assembly and stability of BioSeNPs. BioSeNPs with high stability could be suitable as nutritional supplement to remedy selenium deficiency and in nanomedicine applications.
微生物在将毒性更大的亚硒酸盐和硒酸盐还原为毒性较小的元素硒方面起着至关重要的作用。然而，硒纳米颗粒（SeNPs）的组装过程和稳定性仍未得到充分研究。植物促生根际细菌莱茵氏菌 HX2 可以将亚硒酸盐还原为生物源硒纳米颗粒（BioSeNPs）。在 BioSeNPs 中鉴定出两种主要蛋白质，即鞭毛蛋白 FliC 和孔蛋白 OmpF。fliC 和 ompF 基因突变实验表明，FliC 和 OmpF 可以控制体内 BioSeNPs 的组装。同时，表达和纯化的 FliC 和 OmpF 可以控制体外 SeNPs 的组装。由 R. aquatilis HX2 产生的 BioSeNPs 在各种离子强度下表现出很高的稳定性，而化学合成的 SeNPs（CheSeNPs）则表现出很高的聚集水平。体外实验验证了 FliC 和 OmpF 可以在各种离子强度下防止 CheSeNPs 的聚集。本工作报道了由莱茵氏菌 HX2 菌株制备的高度稳定的 BioSeNPs，并验证了 FliC 和 OmpF 都可以控制 BioSeNPs 的组装和稳定性。具有高稳定性的 BioSeNPs 可以作为营养补充剂来纠正硒缺乏症，并在纳米医学应用中使用。
