Navigation Links
Microbial hair: It's electric

Some bacteria grow electrical hair that lets them link up in big biological circuits, according to a University of Southern California biophysicist and his collaborators.

The finding suggests that microbial colonies may survive, communicate and share energy in part through electrically conducting hairs known as bacterial nanowires.

"This is the first measurement of electron transport along biological nanowires produced by bacteria," said Mohamed El-Naggar, assistant professor of physics and astronomy at the USC College of Letters, Arts and Sciences.

El-Naggar was the lead author of a study appearing online next week in Proceedings of the National Academy of Sciences.

Knowing how microbial communities thrive is the first step in finding ways to destroy harmful colonies, such as biofilms on teeth. Biofilms have proven highly resistant to antibiotics.

The same knowledge could help to promote useful colonies, such as those in bacterial fuel cells under development at USC and other institutions.

"The flow of electrons in various directions is intimately tied to the metabolic status of different parts of the biofilm," El-Naggar said. "Bacterial nanowires can provide the necessary links for the survival of a microbial circuit."

A bacterial nanowire looks like a long hair sticking out of a microbe's body. Like human hair, it consists mostly of protein.

To test the conductivity of nanowires, the researchers grew cultures of Shewanella oneidensis MR-1, a microbe previously discovered by co-author Kenneth Nealson, Wrigley Professor of Geobiology at USC College.

Shewanella tend to make nanowires in times of scarcity. By manipulating growing conditions, the researchers produced bacteria with plentiful nanowires.

The bacteria then were deposited on a surface dotted with microscopic electrodes. When a nanowire fell across two electrodes, it closed the circuit, enabling a flow of measurable current. The conductivity was similar to that of a semiconductor modest but significant.

When the researchers cut the nanowire, the flow of current stopped.

Previous studies showed that electrons could move across a nanowire, which did not prove that nanowires conducted electrons along their length.

El-Naggar's group is the first to carry out this technically difficult but more telling experiment.

Electricity carried on nanowires may be a lifeline. Bacteria respire by losing electrons to an acceptor for Shewanella, a metal such as iron. (Breathing is a special case: Humans respire by giving up electrons to oxygen, one of the most powerful electron acceptors.)

Nealson said of Shewanella: "If you don't give it an electron acceptor, it dies. It dies pretty rapidly."

In some cases, a nanowire may be a microbe's only means of dumping electrons.

When an electron acceptor is scarce nearby, nanowires may help bacteria to support each other and extend their collective reach to distant sources.

The researchers noted that Shewanella attach to electron acceptors as well as to each other, forming a colony in which every member should be able to respire through a chain of nanowires.

"This would be basically a community response to transfer electrons," El-Naggar explained. "It would be a form of cooperative breathing."

El-Naggar and his team are among the pioneers in a young discipline. The term "bacterial nanowire" was coined in 2006. Fewer than 10 studies on the subject have been published, according to co-author Yuri Gorby of The J. Craig Venter Institute in San Diego, discoverer of nanowires in Shewanella.

Gorby and others became interested in nanowires when they noticed that reduction of metals appeared to be occurring around the filaments. Since reduction requires the transfer of electrons to a metal, the researchers suspected that the filaments were carrying a current.

Nanowires also have been proposed as conductive pathways in several diverse microbes.

"The current hypothesis is that bacterial nanowires are in fact widespread in the microbial world," El-Naggar said.

Some have suggested that nanowires may help bacteria to communicate as well as to respire.

Bacterial colonies are known to share information through the slow diffusion of signaling molecules. Nealson argued that electron transport over nanowires would be faster and preferable for bacteria.

"You want the telegraph, you don't want smoke signals," he said.

Bacteria's communal strategy for survival may hold lessons for higher life forms.

In an op-ed published in Wired in 2009, Gorby wrote: "Understanding the strategies for efficient energy distribution and communication in the oldest organisms on the planet may serve as useful analogies of sustainability within our own species."


Contact: Carl Marziali
University of Southern California

Related biology technology :

1. Paratek to Present Clinical Data at the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy
2. Ansell Launches Worldss First Antimicrobial Surgical Glove
3. New AccuPRO-ID™ Microbial Identification Testing Service
4. The toxicity of antimicrobial silver in products can be reduced
5. SynCo Bio Partners Signs New Manufacturing Agreements to Supply the US Market; Securing its Position as a Market Leader in Microbial Biopharmaceutical Contract Production
6. Microban Signs Exclusive Agreement with Sharp Electronics to Launch Calculators with New Microban(R) 3G Silver(TM) Antimicrobial Technology
7. RB Rubber Introduces Environmentally Friendly Antimicrobial Rubber Flooring Products
8. New Antimicrobial Webs Sterilize Medical Implants for 14 Days
9. Novexel Presents 16 Posters and one Slide Presentation at the 49th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) Meeting in San Francisco
10. BioNeutrals Ygiene(TM) Hospital Grade Antimicrobial Proven To Be Completely Inert to Steel In Independent Corrosion Testing
11. Microban Partners With to Launch Yoga Mats With Zinc Antimicrobial Technology
Post Your Comments:
(Date:11/24/2015)... -- Tikcro Technologies Ltd. (OTCQB: TIKRF) today announced that its Annual General Meeting ... Israel time, at the law offices of ... th Floor, Tel Aviv, Israel . ... Izhak Tamir to the Board of Directors; , election of ... approval of an amendment to certain terms of options granted to our ...
(Date:11/24/2015)... , ... November 24, 2015 , ... ... the environment are paramount. Insertion points for in-line sensors can represent a weak ... the InTrac 781/784 series of retractable sensor housings , which are designed ...
(Date:11/24/2015)... , Nov. 24, 2015 /CNW Telbec/ - ProMetic Life Sciences ... today that Mr. Pierre Laurin , President and Chief ... at the upcoming Piper Jaffray 27 th Annual Healthcare ... on December 1-2, 2015. st , at ... one-on-one meetings throughout the day. The presentation will be available ...
(Date:11/24/2015)... , Nov. 24, 2015  PDL BioPharma, Inc. (PDL) (NASDAQ: ... , the company,s president and chief executive officer, will present ... next week in New York City . ... Tuesday, December 1, 2015 at 9:30 a.m. EST. ... to the website at least 15 minutes prior to the ...
Breaking Biology Technology:
(Date:11/19/2015)... , Nov. 19, 2015  Based on its ... & Sullivan recognizes BIO-key with the 2015 Global Frost ... year, Frost & Sullivan presents this award to the ... catering to the needs of the market it serves. ... line meets and expands on customer base demands, the ...
(Date:11/17/2015)... , November 17, 2015 Paris ...   --> Paris from 17 th ... DERMALOG, the biometrics innovation leader, has invented the first combined ... on the same scanning surface. Until now two different scanners ... one scanner can capture both on the same surface. ...
(Date:11/16/2015)... 16, 2015  Synaptics Inc. (NASDAQ: SYNA ... today announced expansion of its TDDI product portfolio ... controller and display driver integration (TDDI) solutions designed ... new TDDI products add to the previously-announced ... (WQHD resolution), and TD4322 (FHD resolution) solutions. All ...
Breaking Biology News(10 mins):