Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/198502

Title

Formation of palladium(0) nanoparticles at microbial surfaces

Author(s)

Bunge, Michael;  Søbjerg, Lina S.;  Rotaru, Amelia-Elena;  Gauthier, Delphine;  Lindhardt, Anders T.;  Hause, Gerd;  Finster, Kai;  Kingshott, Peter;  Skrydstrup, Troels;  Meyer, Rikke L.

Abstract

The increasing demand and limited natural resources for industrially important platinum-group metal (PGM) catalysts render the recovery from secondary sources such as industrial waste economically interesting. In the process of palladium (Pd) recovery, microorganisms have revealed a strong potential. Hitherto, bacteria with the property of dissimilatory metal reduction have been in focus, although the biochemical reactions linking enzymatic Pd(II) reduction and Pd(0) deposition have not yet been identified. In this study we investigated Pd(II) reduction with formate as the electron donor in the presence of Gramnegative bacteria with no documented capacity for reducing metals for energy production: Cupriavidus necator, Pseudomonas putida, and Paracoccus denitrificans. Only large and close-packed Pd(0) aggregates were formed in cell-free buffer solutions. Pd(II) reduction in the presence of bacteria resulted in smaller, well-suspended Pd(0) particles that were associated with the cells (called "bioPd(0)" in the following). Nanosize Pd(0) particles (3-30 nm) were only observed in the presence of bacteria, and particles in this size range were located in the periplasmic space. Pd(0) nanoparticles were still deposited on autoclaved cells of C. necator that had no hydrogenase activity, suggesting a hydrogenaseindependent formation mechanism. The catalytic properties of Pd(0) and bioPd(0) were determined by the amount of hydrogen released in a reaction with hypophosphite. Generally, bioPd(0) demonstrated a lower level of activity than the Pd(0) control, possibly due to the inaccessibility of the Pd(0) fraction embedded in the cell envelope. Our results demonstrate the suitability of bacterial cells for the recovery of Pd(0), and formation and immobilization of Pd(0) nanoparticles inside the cell envelope. However, procedures to make periplasmic Pd(0) catalytically accessible need to be developed for future nanobiotechnological applications.

Publication type

Journal article

Source

Biotechnology and Bioengineering, Vol. 107, no. 2 (Oct 2010), pp. 206-215

Publication year

2010

FOR Code(s)

06 Biological Sciences;  09 Engineering;  10 Technology

Keyword(s)

Bacteria;  Bacterial cells;  Bacterial membrane;  Bacteriology;  Biochemical reactions;  Biosorption;  Buffer;  Buffer solutions;  Catalysts;  Catalytic properties;  Cell envelopes;  Cell immobilisation;  Chemistry;  Cupriavidus necator;  Cytoplasm;  Electron donors;  Energy productions;  Energy yield;  Enzyme activity;  Formates;  Formation mechanism;  Formic acid;  Formic acid derivative;  Gram-negative bacteria;  Hydrogenase;  Hydrogenase activity;  Immobilisation;  In-cell;  Ion beams;  Metabolism;  Metal catalysts;  Metal recovery;  Metal reduction;  Metals;  Microbial surfaces;  Nanoparticles;  Nano-size;  Oxidation reduction reaction;  Oxidation-reduction;  Palladium;  Palladium compounds;  Paracoccus denitrificans;  Particle size;  Periplasm;  Periplasmic space;  Platinum;  Platinum-group metals;  Pseudomonas putida;  Reduction kinetics;  Secondary recovery;  Size ranges;  Surface property

Publisher

Wiley

ISSN

0006-3592

Publisher URL

http://dx.doi.org/10.1002/bit.22801

Copyright

Copyright © 2010 Wiley Periodicals, Inc.

Peer reviewed