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Complexation by cysteine and iron mineral adsorption limit cadmium mobility during metabolic activity of Geobacter sulfurreducens

Title data

Tomaszewski, Elizabeth J. ; Olson, L. ; Obst, Martin ; Byrne, James M. ; Kappler, Andreas ; Muehe, E. Marie:
Complexation by cysteine and iron mineral adsorption limit cadmium mobility during metabolic activity of Geobacter sulfurreducens.
In: Environmental Science : Processes & Impacts. (2020) .
ISSN 2050-7895
DOI: https://doi.org/10.1039/D0EM00244E

Abstract in another language

Cadmium (Cd) adversely affects human health by entering the food chain via anthropogenic activity. In order to mitigate risk, a better understanding of the biogeochemical mechanisms limiting Cd mobility in the environment is needed. While Cd is not redox-active, Cd speciation varies (i.e., aqueous, complexed, adsorbed), and influences mobility. Here, the cycling of Cd in relation to initial speciation during the growth of Geobacter sulfurreducens was studied. Either fumarate or ferrihydrite (Fh) was provided as an electron acceptor and Cd was present as: (1) an aqueous cation, (2) an aqueous complex with cysteine, which is often present in metal stressed soil environments, or (3) adsorbed to Fh. During microbial Fe(III) reduction, the removal of Cd was substantial (∼80% removal), despite extensive Fe(II) production (ratio Fe(II)total : Fetotal = 0.8). When fumarate was the electron acceptor, there was higher removal from solution when Cd was complexed with cysteine (97–100% removal) compared to aqueous Cd (34–50%) removal. Confocal laser scanning microscopy (CLSM) demonstrated the formation of exopolymeric substances (EPS) in all conditions and that Cd was correlated with EPS in the absence of Fe minerals (r = 0.51–0.56). Most notable is that aqueous Cd was more strongly correlated with Geobacter cells (r = 0.72) compared to Cd–cysteine complexes (r = 0.51). This work demonstrates that Cd interactions with cell surfaces and EPS, and Cd solubility during metabolic activity are dependent upon initial speciation. These processes may be especially important in soil environments where sulfur is limited and Fe and organic carbon are abundant.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Heisenberg Professorship - Experimental Biogeochemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Heisenberg Professorship - Experimental Biogeochemistry > Heisenberg Professorship - Experimental Biogeochemistry - Univ.-Prof. Dr. Martin Obst
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 550 Earth sciences, geology
Date Deposited: 27 Aug 2020 07:44
Last Modified: 27 Aug 2020 07:44
URI: https://eref.uni-bayreuth.de/id/eprint/56621