What are cable bacteria and they work?

Long networks of bacteria known as “cable bacteria” move electrons among themselves. These microorganisms conduct electricity in this interesting bacterial cable.

Cable bacteria are multicellular bacterial organisms meaning many bacteria from the same family are living very closely together. They usually share the same food and nutrients and help each other out. This tightness makes the whole bacterial community stronger and often gives them new superpowers- like in this case, the multicellular cable bacteria can conduct electricity. Until now, researchers do not know much about cable bacteria, as they usually live in marine, freshwater, and salt-marsh sediments. Here, they often use unusual components like sulfur or sulfur complexes to gain energy and grow. Such conditions are pretty difficult to imitate. So currently, researchers are struggling to grow them in a lab. However, recent studies managed to find out what cable bacteria look like and how cable bacteria conduct electricity.

What do cable bacteria look like?

For this, researchers took water samples from different locations. They then visualized the cable bacteria with different spectroscopic techniques. With these machines, researchers can magnify the tiniest things and get high-resolution pictures of bacterial cells. They were able to see that a single “cable bacteria” is a multicellular creature. They look like long chains or cables. Researchers refer to these chains or cables as filaments, and they can be up to 7cm long.

What is the composition of cable bacteria?

The cable bacteria family is still being classified by researchers. Yet, they are currently aware that rod-shaped Gram-negative bacteria are cable bacteria. This indicates that the bacteria are enclosed and protected by an inner and an outer membrane. The periplasm, a liquid gap between the inner and outer membranes, is typically present. This area functions somewhat as a supple, flexible buffer zone between the two membranes. Nevertheless, with cable bacteria, each bacterial cell is encased in an inner membrane to safeguard the contents of the cell.  As you can see, the entire arrangement does actually resemble a cable and insulates the inside-outside microorganisms. Essentially, it is how these bacteria received their name.

How do cable bacteria move electrons and conduct electricity?

Why did they even choose to create a digital currency? The quick action is to survive. So let’s examine this more closely. Cable bacteria are present in water sediments. These waters have a lot of oxygen in the highest layers close to the surface. They are also sulfur-rich in the deeper strata. Additionally, this oxygen-sulfur gradient is used by cable bacteria to carry electricity. These days, cable bacteria actually locate themselves parallel to the coast when there is oxygen in the sea. This shows that the cable has one end at the bottom, where sulfur is abundant, and the other end at the top, where oxygen is abundant. 

Sulfur-breathing bacteria conduct electricity

The filament now functions as a half-cell. The sulfur is “breathed” by the bacteria in the deeper layers. An anodic half-reaction results in the production of electrons (e-) and protons (H+). These electrons then go up the cable to the upper portion of the cable while moving through the liquid periplasm. In this instance, the bacteria eat these electrons in a cathodic half-reaction to deplete oxygen. The metabolism of each cell includes these oxidation and reduction activities. This thereby maintains the life of every cell.

Yet, typically, both reactions take place inside of the same cell, allowing one cell to benefit from both processes’ energy simultaneously. It’s interesting to note that cable bacteria managed to separate the oxidation and reduction processes. As a result, the mechanisms of oxidation and reduction occur in distinct cells, with one reaction taking place in the cells at the bottom of the cable and the other in the cells at the top. But, they discovered a way to perform both activities using the cable as a single system. This is the truly amazing portion.

For the environment, what does it mean?

The cable bacteria’s peculiar metabolism has some intriguing consequences on their surroundings. In the deeper water layer, these processes generate protons, while in the top layer, they diminish them. This causes the pH in the deeper layer to decrease and the pH close to the surface to rise. Metal complexes may be mineralized or demineralized as a result. According to research, these processes of (de-)mineralization also have an effect on the geochemistry of the surrounding environment in the water. Yet, it is still unclear precisely how the metabolism of cable bacteria affects the environment and perhaps other species.

It is understandable that there are still a lot of unsolved concerns considering that the cable bacterium was only recently identified by experts. But I’m confident that we will learn a lot more fascinating information about them, and who knows- perhaps someday, bacteria will power batteries made of seawater.