Electric cable bacteria breathe oxygen with unheard efficiency

February 10, 2021

Ten years ago, researchers at Aarhus University, Denmark, reported the discovery of centimeter-long cable bacteria, that live by conducting an electric current from one end to the other. Now the researchers document that a few cells operate with extremely high oxygen consumption while the rest of the cells process food and grow without oxygen. An outstanding way of life.

We humans need food and oxygen to live.

Now, imagine if oxygen was to be found only at the mountain top and food only in the valley. That's how the world looks like for cable bacteria, which live in the bottom of seas and lakes. For them, oxygen is available only at the very surface of the bottom, whereas the food is buried centimeters down.


"While other organisms try to solve the problem by moving oxygen and food up and down, cable bacteria have developed electric wires. When consuming food they produce electrons and send them through the 'biowires' to the surface for reduction of oxygen from the overlying water," says Lars Peter Nielsen, head of Center for Electromicrobiology, Aarhus University, Denmark.

A cable bacterium consists of many cells in line. It can grow centimeters long, the cells encased in a common coat wherein the wires stretch.

The researchers placed cable bacteria in a little, transparent chamber. In the middle, the bacteria had access to oxygen-free mud stuffed with food, while oxygen diffused in from the edges. Right where the intruding oxygen was depleted, numerous unicellular bacteria formed a distinct front. In that specific position they fought to capture food and oxygen from either side simultaneously.

"In the microscop, I watched how single cable bacteria placed themselves across the front with one end into the zone with oxygen," explains Stefano Scilipoti, PhD-student at Center for Electromicrobiology, Aarhus University and the primary discoverer.

Less than 10% of the cells are "breathing"

Stefano Scilipoti watched how one single cable bacterium could distort the front made by unicellular, swimming bacteria. The cable bacterium respired so much oxygen that the unicellular bacteria had to move closer to the edge of the chamber to sustain the oxygen supply needed for their respiration. The cable bacterium could just dip a few cells in oxygen, and the magnitude of the distortion - in laboratory jargon called 'bump' - allowed to calculate how much oxygen was being consumed.

"Less than 10% of the cells of the cable bacterium consumed oxygen but they did it with a rate matching the highest rates known in biology. That only works because the cable bacterium runs an electric current between the cells being in contact with oxygen and the cells processing the food. The cells consuming oxygen can thus focus on this task only, while the other cells digest food and generate new cells," says Stefano Scilipoti.

The cable bacterial machinery

The ancestors of cable bacteria lived without any oxygen. Anaerobic bacteria, as you call them. For these bacteria, oxygen is toxic and a prolonged exposure eventually lead them to death. With the evolution of electric connection to oxygen however, cable bacteria can explore the strength of breathing with oxygen without exposing many cells to oxygen stress, thus getting the best of oxygen (more energy) and avoiding the rest (damage to the cells).

At Center for Electromicrobiology, the chase to unravel the special mechanisms that enable this unique electric form of life continues.
Further information:

Ph.D.-student Stefano Scilipoti, Center for Electromicrobiology at Aarhus University; mail: ss@bio.au.dk; phone: +45 9148 9338.

Professor Lars Peter Nielsen, Center for Electromicrobiology at Aarhus University; mail: lpn@bio.au.dk; phone: +45 6020 2654.

Original paper in Science Advances: http://advances.sciencemag.org/cgi/content/full/7/7/eabe1870/DC1

Link to video: http://dx.doi.org/10.17632/jhwd3dtwmd.1

Aarhus University

Related Bacteria Articles from Brightsurf:

Siblings can also differ from one another in bacteria
A research team from the University of Tübingen and the German Center for Infection Research (DZIF) is investigating how pathogens influence the immune response of their host with genetic variation.

How bacteria fertilize soya
Soya and clover have their very own fertiliser factories in their roots, where bacteria manufacture ammonium, which is crucial for plant growth.

Bacteria might help other bacteria to tolerate antibiotics better
A new paper by the Dynamical Systems Biology lab at UPF shows that the response by bacteria to antibiotics may depend on other species of bacteria they live with, in such a way that some bacteria may make others more tolerant to antibiotics.

Two-faced bacteria
The gut microbiome, which is a collection of numerous beneficial bacteria species, is key to our overall well-being and good health.

Microcensus in bacteria
Bacillus subtilis can determine proportions of different groups within a mixed population.

Right beneath the skin we all have the same bacteria
In the dermis skin layer, the same bacteria are found across age and gender.

Bacteria must be 'stressed out' to divide
Bacterial cell division is controlled by both enzymatic activity and mechanical forces, which work together to control its timing and location, a new study from EPFL finds.

How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.

The bacteria building your baby
Australian researchers have laid to rest a longstanding controversy: is the womb sterile?

Hopping bacteria
Scientists have long known that key models of bacterial movement in real-world conditions are flawed.

Read More: Bacteria News and Bacteria Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.