DqsIR quorum sensing system and Biosynthesis of gold nanoparticles

2017-06-12 16:00:00
报告题目:Extremophilic bacterium Deinococcus radiodurans: DqsIR quorum sensing system and Biosynthesis of gold nanoparticles
报告时间:2017.06.13 周二 9:30

报告人简介:田兵,浙江大学教授,博士生导师,教育部新世纪优秀人才。2002年毕业于大连理工大学生物化工专业,获博士学位。先后在日本放射医学综合研究所、美国宾夕法尼亚大学医学院微生物系访学。主要研究方向:极端微生物环境抗性的代谢分子基础、有效成分合成途径及其调控机制;功能基因资源和基因组学研究;微生物在生态修复、新材料合成等领域的应用。主持或参加了20多项科研项目,已在Molecular Microbiology、Trends in Microbiology、eLife、Frontiers in Microbiology、Molecular BioSystems、Microbiology-SGM等刊物上发表SCI论文60多篇,获得授权发明专利4项。

Deinococcus radiodurans, which belongs to the unique phylum Deinococcus-Thermus, is an extreme bacterium known for its high resistance to stresses including radiation and oxidants. Here, we show that an AHL-mediated quorum-sensing system (DqsI/DqsR) was identified in D. radiodurans. We found that under non-stress conditions, the AHL level was “shielded” by quorum quenching enzymes, whereas AHLs accumulated when D. radiodurans was exposed to oxidative stress. Mutants deficient in DqsIR quorum sensing were more sensitive to oxidative stress compared with the wild-type strain. The DqsR, acting as a regulator of quorum sensing, controls gene expression along with AHLs. The DqsIR quorum sensing that mediates gene regulation is an adaptive strategy for D. radiodurans in response to oxidative stresses.
The ability of D. radiodurans to reduce Au(III) and biosynthesize gold nanoparticles (AuNPs) was investigated in aqueous solution by UV/Vis absorption spectroscopy, electron microscopy, XRD, DLS, FTIR and XPS. D. radiodurans efficiently synthesized AuNPs from Au(III) solution. AuNPs were distributed in the cell envelope, across the cytosol and in the extracellular space. Through interactions with carboxyl, amine, phospho and hydroxyl groups, Au(III) may be reduced to Au(I), and further reduced to Au(0) with the capping groups to stabilize the AuNPs. The extreme bacterium D. radiodurans can be used as a novel bacterial candidate for efficient biosynthesis of AuNPs, which exhibited potential in biomedical application.

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