Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bacterium takes a shine to metals

19.06.2006
Experiments suggest a new form of living protection for copper and other metallic surfaces

Exposed metal surfaces are highly vulnerable to corrosion, but paint or other protective coatings can interfere with some uses, as well as add significant costs. Now, a comprehensive series of experiments suggests a new form of protection: bacteria.


Brass, mild steel (MS) and copper (Cu) samples compared after incubation with (+MR1) and without the presence of the bacteria. Credit: Corrosion and Environmental Effects laboratory, Mork Family Department of Materials Science and Chemical Engineering, Viterbi School of Engineering

Viterbi School post-doctoral researcher Ersa Kus, is the lead author on a forthcoming report on experiments by a team of materials scientists analyzing the ability of an organism called Shewanella oneidensis MR-1 (hereinafter MR-1) to protect a number of metals. The team made a preliminary presentation at a Denver conference last month, and will make a more detailed one in Mexico in October.

Scientists have long known that some bacteria can accelerate corrosion on metal surfaces, says Kus, who works in the Corrosion and Environmental Effects laboratory of Professor Florian Mansfeld of the Viterbi School's Mork Family Department of Materials Science and Chemical Engineering. A bacterium of the same genus as MR-1, S. algae, has earlier been shown to prevent pitting of aluminum and some steel.

MR-1 is a remarkable organism that can incorporate metal into its metabolism, "inhaling certain metal oxides and compounds in one form, exhaling them in another," according to Kus's presentation. MR-1 has previously been used to precipitate uranium out of contaminated water. And "it can grow almost anywhere and does not cause disease in humans or animals," Kus notes.

And it can protect metal.

The experiment was simple. Matched pairs of samples of four metals -- aluminum 2024, zinc, mild steel, copper, and brass -- were prepared. One sample set of each pair was incubated in a growth medium containing MR-1; the other in a sterile bath of the same growth medium, containing neither MR-1 nor any other organism.

After a week, corrosion was monitored, both visually and by measuring electrochemical impedance (resistance to conducting alternating current.) Because electrical effects play a role in many forms of corrosion, higher AC impedance is associated with increased corrosion resistance.

The results were clearcut. For all the materials, impedance increased with exposure to bacteria, and the longer the metals were exposed, the more resistant they became. The increase was particularly marked in the aluminum samples. By the end of the week the control samples showed obvious visual pitting, while the ones with MR-1 colonies were unscathed.

The pattern of impedance varied from metal to metal. Aluminum showed drastic reduction in resistance to electrical currents in all frequencies. Brass and, particularly copper showed nearly as dramatic an effect -- readings indicated active corrosion in the control samples, but a large reduction in the MR-1 samples. The copper MR1 samples, in fact, showed a profile similar to that demonstrated by copper covered with a protective polymer plastic film.

The patterns for steel and zinc were much less marked, but still significant, as was the difference in the metals' appearance.

The next step, according to Kus, is to figure out exactly what is going on and determine where and how the presence of bacteria is altering the corrosion equation. To do this, the group will be making molecular scale analysis of bacteria/metal interfaces, and looking to determine what the properties of MR1 biofilm are, as well as why the pattern of interaction differs from metal to metal.

While MR1 itself may not be the metal protector of the future, it may well suggest an agent that can be, Kus says. The research will be presented at the 210th Meeting of The Electrochemical Society in Cancun, Mexico, October 29-November 3, 2006

Eric Mankin | EurekAlert!
Further information:
http://www.usc.edu

More articles from Materials Sciences:

nachricht New approach to revolutionize the production of molecular hydrogen
22.05.2017 | Technische Universität Dresden

nachricht Photocatalyst makes hydrogen production 10 times more efficient
19.05.2017 | Kobe University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

Im Focus: Hydrogen Bonds Directly Detected for the First Time

For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel’s Swiss Nanoscience Institute network have reported the results in the journal Science Advances.

Hydrogen is the most common element in the universe and is an integral part of almost all organic compounds. Molecules and sections of macromolecules are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

Media accreditation opens for historic year at European Health Forum Gastein

16.05.2017 | Event News

 
Latest News

New approach to revolutionize the production of molecular hydrogen

22.05.2017 | Materials Sciences

Scientists enlist engineered protein to battle the MERS virus

22.05.2017 | Life Sciences

Experts explain origins of topographic relief on Earth, Mars and Titan

22.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>