Featured Research

from universities, journals, and other organizations

Bacterium Takes A Shine To Metals: New Form Of Living Protection For Copper And Other Metallic Surfaces?

Date:
June 16, 2006
Source:
University of Southern California
Summary:
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

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.

Researchers at the Corrosion and Environmental Effects Laboratory of (CEEL) USC Viterbi School have been working on analyzing the ability of an organism called Shewanella oneidensis MR-1 (hereinafter MR-1) to protect a number of metals.

The director of CEEL Prof. Florian Mansfeld and PhD candidate Esra Kus have been collaborating with Prof. Ken Nealson of Department of Earth Sciences. The team made a preliminary presentation at a Denver conference last month, and will make a more detailed one in Mexico in October.

The concept of Microbiologically Influenced Corrosion Inhibition has been discussed in the scientific literature since 1997. Researchers at the University of Connecticut, University of Southern California and the University of California at Irvine had reported corrosion inhibition in their earlier studies by means other organisms and regenerative biofilms.

In a study in 2001 Mansfeld and Nagiub reported microbiologically influenced corrosion inhibition for Al2024, mild steel, cartridge brass and stainless steel when bacteria contaminated an artificial seawater solution containing growth medium. They also showed that a bacterium of the same genus as MR-1, S. algae, prevented pitting of aluminum and some steel.

MR-1, first discovered by USC Professor Ken Nealson of the USC department of Earth Sciences, who is a co-author on the study 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 Denver 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," they note.

And it can protect metal.

The experiment performed at CEEL was simple. Matched pairs of samples of five 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 clear-cut. 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 MR-1 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 Mansfeld, 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 MR-1 biofilm are, as well as why the pattern of interaction differs from metal to metal.

While MR-1 itself may not be the metal protector of the future, it may well suggest an agent that can be, Mansfeld says. The research will be presented at the 210th Meeting of the Electrochemical Society in Cancun, Mexico, October 29-November 3, 2006.


Story Source:

The above story is based on materials provided by University of Southern California. Note: Materials may be edited for content and length.


Cite This Page:

University of Southern California. "Bacterium Takes A Shine To Metals: New Form Of Living Protection For Copper And Other Metallic Surfaces?." ScienceDaily. ScienceDaily, 16 June 2006. <www.sciencedaily.com/releases/2006/06/060616130207.htm>.
University of Southern California. (2006, June 16). Bacterium Takes A Shine To Metals: New Form Of Living Protection For Copper And Other Metallic Surfaces?. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2006/06/060616130207.htm
University of Southern California. "Bacterium Takes A Shine To Metals: New Form Of Living Protection For Copper And Other Metallic Surfaces?." ScienceDaily. www.sciencedaily.com/releases/2006/06/060616130207.htm (accessed July 23, 2014).

Share This




More Matter & Energy News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com
Boeing Ups Outlook on 52% Profit Jump

Boeing Ups Outlook on 52% Profit Jump

Reuters - Business Video Online (July 23, 2014) Commercial aircraft deliveries rose seven percent at Boeing, prompting the aerospace company to boost full-year profit guidance- though quarterly revenues missed analyst estimates. Bobbi Rebell reports. Video provided by Reuters
Powered by NewsLook.com
Europe's Car Market on the Rebound?

Europe's Car Market on the Rebound?

Reuters - Business Video Online (July 23, 2014) Daimler kicks off a round of second-quarter earnings results from Europe's top carmakers with a healthy set of numbers - prompting hopes that stronger sales in Europe will counter weakness in emerging markets. Hayley Platt reports. Video provided by Reuters
Powered by NewsLook.com
9/11 Commission Members Warn of Terror "fatigue" Among American Public

9/11 Commission Members Warn of Terror "fatigue" Among American Public

Reuters - US Online Video (July 22, 2014) Ten years after releasing its initial report, members of the 9/11 Commission warn of the "waning sense of urgency" in combating terrorists attacks. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins