Biomagnetic Recovery and Bioaccumulation of Selenium Granules in Magnetotactic Bacteria.
Using microorganisms to remove waste and/or neutralize pollutants from contaminated water is attracting much attention due to the environmentally friendly nature of this methodology. However, cell recovery remains a bottleneck and a considerable challenge for the development of this process. Magnetotactic bacteria are a unique group of organisms that can be manipulated by an external magnetic field due to the presence of biogenic magnetite crystals formed within their cells. In this study, we demonstrated an account of accumulation and precipitation of amorphous elemental selenium nanoparticles within magnetotactic bacteria alongside and independent of magnetite crystal biomineralization when grown in a medium containing selenium oxyanion (SeO3 (2-)). Quantitative analysis shows that magnetotactic bacteria accumulate the largest amount of target molecules (Se) per cell compared with any other previously reported nonferrous metal/metalloid. For example, 2.4 and 174 times more Se is accumulated than Te taken up into cells and Cd(2+) adsorbed onto the cell surface, respectively. Crucially, the bacteria with high levels of Se accumulation were successfully recovered with an external magnetic field. The biomagnetic recovery and the effective accumulation of target elements demonstrate the potential for application in bioremediation of polluted water.



The development of a technique for effective environmental water remediation is urgently required across the globe. A biological remediation process of waste removal and/or neutralization of pollutant from contaminated water using microorganisms has great potential, but cell recovery remains a bottleneck. Magnetotactic bacteria synthesize magnetic particles within their cells, which can be recovered by a magnetic field. Herein, we report an example of accumulation and precipitation of amorphous elemental selenium nanoparticles within magnetotactic bacteria independent of magnetic particle synthesis. The cells were able to accumulate the largest amount of Se compared to other foreign elements. More importantly, the Se-accumulating bacteria were successfully recovered with an external magnetic field. We believe magnetotactic bacteria confer unique advantages of biomagnetic cell recovery and of Se accumulation, providing a new and effective methodology for bioremediation of polluted water.
Division of Biotechnology and Life Science, Institute of Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan.|School of Physics and Astronomy, University of Leeds, Leeds, United Kingdom.|Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan.
Masayoshi
M
Tanaka
School of Physics and Astronomy, University of Leeds, Leeds, United Kingdom.
William
W
Knowles
School of Physics and Astronomy, University of Leeds, Leeds, United Kingdom.
Rosemary
R
Brown
School of Chemical and Process Engineering, University of Leeds, Leeds, United Kingdom.
Nicole
N
Hondow
Division of Biotechnology and Life Science, Institute of Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan.
Atsushi
A
Arakaki
Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.
Stephen
S
Baldwin
School of Physics and Astronomy, University of Leeds, Leeds, United Kingdom s.s.staniland@sheffield.ac.uk tmatsuna@cc.tuat.ac.jp.|Department of Chemistry, University of Sheffield, Sheffield, United Kingdom.
Sarah
S
Staniland
Division of Biotechnology and Life Science, Institute of Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan s.s.staniland@sheffield.ac.uk tmatsuna@cc.tuat.ac.jp.
Tadashi
T
Matsunaga
D001419:Bacteria / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry; D008280:Magnetics; D053768:Metal Nanoparticles; D012643:Selenium / Q000378:metabolism*
D003470:Culture Media; D012643:Selenium