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Electric bacteria in the spotlight

Several years ago, researchers from Aarhus discovered a curious form of electric life on the seafloor. Since then it has become increasingly clear that a significant part of the bacterial world is electrified. Leading researchers from around the world will set this life form in focus at the first-ever electromicrobiology conference, held on March 21 and 22 in Aarhus, Denmark.

2019.03.18 | Peter Bondo

[Translate to English:] Elektriske kabelbakterier blev opdaget i Aarhus Bugt af forskere fra Aarhus Universitet og de har nu beskrevet fem arter. Tre i Aarhus Bugt og to i Giber å. Den første art fik selvfølgelig navnet: Electrothrix aarhusiensis. Her er det et tværsnit af en kabelbakterie med de karakteristiske ribber, som indeholder elektriske ledninger. Foto: Chr. Bortolini & K. Thomsen.

Electrical cable bacteria were discovered in Aarhus Bay by researchers from Aarhus University, who have described five species of these bacteria so far: three from Aarhus Bay and two from Giber stream. The first species was naturally given the name Electrothrix aarhusiensis. This is a cross section of a cable bacterium with its characteristic ridges containing electrical wires. Photo: Chr. Bortolini & K. Thomsen.

Farvning af forskellige dele af arvematerialet (DNA og RNA) viser store forskelle mellem cellerne i en kabelbakterie og en tiltrækning af helt andre bakterier, som måske har elektrisk samarbejde med kabelbakterierne. Foto: Britta Poulsen.

Staining of the different nucleic acids (DNA and RNA) shows great variation between cells in a cable bacterium and the attraction of other bacteria that may cooperate electrically with cable bacteria. Photo: Britta Poulsen.

Kabelbakterier fungerer som flere centimeter lange, elektriske kabler i havbunden. Foto: Steffen Larsen

Cable bacteria act as electrical cables several centimetres in length in the seabed. Photo: Steffen Larsen

’It is dizzying to think about what we’re dealing with here’

These words are from Professor Lars Peter Nielsen, head of the Center for Electromicrobiology at Aarhus University.

Just ten years ago Lars Peter Nielsen discovered that electrical currents could explain some counter-intuitive processes measured in mud from Aarhus Harbour, Denmark. This led to the spectacular discovery of cable bacteria: bacteria several centimetres in length with internal electrical wires.

It turns out that many other peculiar and important phenomena in microbiology can be explained with electrical connections. The Center for Electromicrobiology and the Danish National Research Foudation have invited 100 researchers from all over the world to Aarhus, Denmark, for the first-ever international conference on electromicrobiology, with the theme ”from electrons to ecosystems”.

New bacterial world order

The discovery that bacteria can produce and transmit electrical currents to other organisms and substances indicates a need to revise our understanding of microbial communities.

”We once thought that bacteria were restricted to exchanging substances with their direct surroundings, and in some cases using sunlight. However, if bacteria can produce or live off electrical currents, they can take advantage of many different and more efficient processes. For one thing, electrical currents enable previously unknown forms of cooperation with other organisms. We can draw an analogy to how the telephone and the electrical grid have vastly expanded our ability to communicate and use energy,” explains Lars Peter.

One of the key topics at the conference will be the question of how biological structures conduct electrical currents with the strength that has been measured. Many believe that bacteria make efficient electrical conductors from pure protein, and there are many potential electronic applications for this type of organic conductor. Protein wires could be produced with green technology and are, to name one example, of great interest to the medical community as a means to connect the human body to electronic devices for measurement and healing.

Bacteria also work wirelessly. Cable bacteria generate electric fields that influence the transport of nearby nutrients. These fields can be measured at distances of up to several metres and probably reveal where cable bacteria are in the process of degrading groundwater contaminants. Another topic at the conference will be how atmospheric electrical disturbances affect microbial processes in the ground and the ocean.

The origin of life

The ability to exchange electrons may be a basic, unremarkable  property of life that has existed since the origin of life itself.

One research group participating in the conference has discovered electrical life around hot volcanic vents in the deep sea, and based on this have formulated a theory that the first life forms on Earth were based on electrical energy. These life forms would have produced organic compounds from carbon dioxide via direct use of electrons generated by geological processes. This is a more simple process than using chemical energy or light energy, which have previously been proposed as the energy source for the origin of life.

Too far out there?

It is overwhelming how many different microorganisms, processes, and environments have some degree of electron exchange. From the deep subsurface and contaminated rivers to biofilms and biogas reactors, from photosynthetic and metal-cycling bacteria to dangerous bacteria in the body.

”When you hear a lot of these theories, you think, ’Wow, that seems a bit too far out there’. But we mustn’t be too quick to dismiss these theories, and cable bacteria have shown us how reality can outdo our wildest imagination. We are still just beginning to understand electromicrobiology, and there’s nothing better than subjecting your ideas to critical scientific discussion at a conference,” says Lars Peter Nielsen.

The conference in Aarhus, Denmark, is attracting researchers from microbiology, physics, geology, molecular biology, engineering, and many other fields. These researchers may have widely different backgrounds, but they share the common goal of opening the door to a brand new microbial world.

Conference website: http://conferences.au.dk/electromicrobiology/

Additional information:

Professor, Centerleder Lars Peter Nielsen, Center for Elektromikrobiologi, Aarhus Universitet, Denmark; mail: lpn@bios.au.dk; tlf.: 6020 2654

Centeradministrator Maria Blach Nielsen, Center for Elektromikrobiologi, Aarhus Universitet, Denmark; mail: mbn@bios.au.dk; tlf.: 51371192

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