Biomineralization of Cu<sub>2</sub>S Nanoparticles by <i>Geobacter sulfurreducens</i>



Kimber, Richard L, Bagshaw, Heath ORCID: 0000-0001-7209-9132, Smith, Kurt, Buchanan, Dawn M, Coker, Victoria S, Cavet, Jennifer S and Lloyd, Jonathan R
(2020) Biomineralization of Cu<sub>2</sub>S Nanoparticles by <i>Geobacter sulfurreducens</i>. APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 86 (18). e00967-e00920.

[img] Text
BIomineralisation of Cu2S nanoparticles by Geobacter sulferreducens - Kimber-Bagshaw-Smith etc 2020.pdf - Author Accepted Manuscript

Download (1MB) | Preview

Abstract

Biomineralization of Cu has been shown to control contaminant dynamics and transport in soils. However, very little is known about the role that subsurface microorganisms may play in the biogeochemical cycling of Cu. In this study, we investigate the bioreduction of Cu(II) by the subsurface metal-reducing bacterium <i>Geobacter sulfurreducens</i> Rapid removal of Cu from solution was observed in cell suspensions of <i>G. sulfurreducens</i> when Cu(II) was supplied, while transmission electron microscopy (TEM) analyses showed the formation of electron-dense nanoparticles associated with the cell surface. Energy-dispersive X-ray spectroscopy (EDX) point analysis and EDX spectrum image maps revealed that the nanoparticles are rich in both Cu and S. This finding was confirmed by X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses, which identified the nanoparticles as Cu<sub>2</sub>S. Biomineralization of Cu<sub>x</sub>S nanoparticles in soils has been reported to enhance the colloidal transport of a number of contaminants, including Pb, Cd, and Hg. However, formation of these Cu<sub>x</sub>S nanoparticles has only been observed under sulfate-reducing conditions and could not be repeated using isolates of implicated organisms. As <i>G. sulfurreducens</i> is unable to respire sulfate, and no reducible sulfur was supplied to the cells, these data suggest a novel mechanism for the biomineralization of Cu<sub>2</sub>S under anoxic conditions. The implications of these findings for the biogeochemical cycling of Cu and other metals as well as the green production of Cu catalysts are discussed.<b>IMPORTANCE</b> Dissimilatory metal-reducing bacteria are ubiquitous in soils and aquifers and are known to utilize a wide range of metals as terminal electron acceptors. These transformations play an important role in the biogeochemical cycling of metals in pristine and contaminated environments and can be harnessed for bioremediation and metal bioprocessing purposes. However, relatively little is known about their interactions with Cu. As a trace element that becomes toxic in excess, Cu can adversely affect soil biota and fertility. In addition, biomineralization of Cu nanoparticles has been reported to enhance the mobilization of other toxic metals. Here, we demonstrate that when supplied with acetate under anoxic conditions, the model metal-reducing bacterium <i>Geobacter sulfurreducens</i> can transform soluble Cu(II) to Cu<sub>2</sub>S nanoparticles. This study provides new insights into Cu biomineralization by microorganisms and suggests that contaminant mobilization enhanced by Cu biomineralization could be facilitated by <i>Geobacter</i> species and related organisms.

Item Type: Article
Uncontrolled Keywords: Geobacter sulfurreducens, copper, nanoparticles, Cu2S, bioreduction
Depositing User: Symplectic Admin
Date Deposited: 21 Sep 2020 09:33
Last Modified: 02 Feb 2024 05:09
DOI: 10.1128/AEM.00967-20
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3101705