Biosynthesis of selenium nanoparticles by Azoarcus sp. CIB

Microbial Cell Factories

Research

Eduardo Díaz¹  Helga Fernández-Llamosas¹  Manuel Carmona¹  María Luisa Blázquez²  Laura Castro² 

[1] Environmental Biology Department, Centro de Investigaciones Biológicas-CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain;Material Science and Metallurgical Engineering Department, Facultad de Químicas, Universidad Complutense de Madrid, Madrid, Spain;

关键词: Nanoparticles;    Selenium;    Bioremediation;    Azoarcus;    Rice;    Nanotechnology;    Biotechnology;   

DOI  :  10.1186/s12934-016-0510-y

 received in 2016-01-27, accepted in 2016-06-07,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundDifferent bacteria have been reported so far that link selenite resistance to the production of metallic selenium nanoparticles (SeNPs). Although SeNPs have many biotechnological applications in diverse areas, the molecular mechanisms involved in their microbial genesis are not fully understood. The Azoarcus genus is a physiologically versatile group of beta-proteobacteria of great environmental relevance. Azoarcus sp. CIB is a facultative anaerobe that combines the ability to degrade under aerobic and/or anaerobic conditions a wide range of aromatic compounds, including some toxic hydrocarbons such as toluene and m-xylene, with an endophytic life style in the root of rice. We unravel here an additional physiological feature of the strain CIB that is related to its resistance to selenium oxyanions and the formation of SeNPs.ResultsThis work is the first report of a member of the Azoarcus genus that is able to anaerobically grow in the presence of selenite. Electron microscopy preparations and X-ray spectroscopy analyses demonstrate the reduction of selenite to spherical electron-dense SeNPs whose average size was 123 ± 35 nm of diameter. Our data suggest that the main molecular mechanism of selenite resistance resides on an energy-dependent selenite exporter. Azoarcus cells trigger the synthesis of SeNPs when they reach the stationary-phase of growth, and either the exhaustion of electron donor or acceptor, both of which lead to starvation conditions, produce the reduction of selenite to red elemental selenium. Azoarcus becomes a promising biocatalyst, either as whole cells or cellular extracts, for the anaerobic and/or aerobic green synthesis of SeNPs.ConclusionsAzoarcus turns out to be a new eco-friendly system to reduce selenite and produce spherical SeNPs. Moreover, this is the first report of a rice endophyte able to produce SeNPs. Since Azoarcus is also able to degrade both aerobically and anaerobically toxic aromatic compounds of great environmental concern, it becomes a suitable candidate for a more sustainable agricultural practice and for bioremediation strategies.

【 授权许可】

CC BY   
© The Author(s) 2016