Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Progress Toward a Biological Fuel Cell?

Metal-reducing bacteria and semiconducting nanominerals aggregate to form electrically conducting networks

Biological fuel cells use enzymes or whole microorganisms as biocatalysts for the direct conversion of chemical energy to electrical energy. One type of microbial fuel cell uses anodes (positive electrodes) coated with a bacterial film. The fuel consists of a substrate that the bacteria can break down.

The electrons released in this process must be transferred to the anode in order to be drawn off as current. But how can the electrons be efficiently conducted from the microbial metabolism that occurs inside a cell to the anode? Discoveries made by Japanese researchers regarding the electron-transfer mechanism of Shewanella loihica PV-4 suggest an intriguing approach. As reported in the journal Angewandte Chemie, in the presence of iron(III) oxide nanoparticles, these metal-reducing bacteria aggregate into an electrically conducting network.

To meet its energy requirements, our bodies metabolize energy-rich substances. A critical step in this process is the transfer of electrons to oxygen, which enters our bodies when we breathe. Instead of breathing, metal-reducing bacteria that live in subterranean sediments transfer electrons to the iron oxide minerals on which they dwell as the last step of their metabolism. In this process, trivalent iron ions are reduced to divalent ions.

A team led by Kazuhito Hashimoto has investigated how this transfer is carried out in Shewanella loihica. They added the cells to a solution containing very finely divided nanoscopic iron(III) oxide particles and poured the solution into a chamber containing electrodes. A layer of bacteria and iron oxide particles was rapidly deposited onto the indium tin oxide electrodes at the bottom of the chamber. When the cells were “fed” lactate, a current was detected. Electrons from the metabolism of the lactate are thus transferred from the bacteria to the electrode.

Scanning electron microscope images show a thick layer of cells and nanoparticles on the electrode; the surfaces of the cells are completely coated with iron oxide particles. The researchers were able to show that the semiconducting properties of the iron oxide nanoparticles, which are linked to each other by the cells, contribute to the surprisingly high current. The cells act as an electrical connection between the individual iron oxide particles. Cytochromes, enzymes in the outer cell membrane of these bacteria, transfer electrons between the cells and the iron oxide particles without having to overcome much of an energy barrier. The result is a conducting network that even allows cells located far from the electrode to participate in the generation of current.

Author: Kazuhito Hashimoto, University of Tokyo (Japan),

Title: Self-Constructed Electrically Conductive Bacterial Networks

Angewandte Chemie International Edition 2009, 48, No. 3, 508–511, doi: 10.1002/anie.200804750

Kazuhito Hashimoto | Angewandte Chemie
Further information:

More articles from Life Sciences:

nachricht When fat cells change their colour
28.10.2016 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Aquaculture: Clear Water Thanks to Cork
28.10.2016 | Technologie Lizenz-Büro (TLB) der Baden-Württembergischen Hochschulen GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel light sources made of 2D materials

Physicists from the University of Würzburg have designed a light source that emits photon pairs. Two-photon sources are particularly well suited for tap-proof data encryption. The experiment's key ingredients: a semiconductor crystal and some sticky tape.

So-called monolayers are at the heart of the research activities. These "super materials" (as the prestigious science magazine "Nature" puts it) have been...

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Prototype device for measuring graphene-based electromagnetic radiation created

28.10.2016 | Power and Electrical Engineering

Gamma ray camera offers new view on ultra-high energy electrons in plasma

28.10.2016 | Physics and Astronomy

When fat cells change their colour

28.10.2016 | Life Sciences

More VideoLinks >>>