Many bacteria are extremely helpful to us. They digest our food, they keep us healthy or they help us in industrial processes. By now, we learned to use bacteria and their superpowers in many different applications.
And surely, our bodies would not be the same without our bacterial friends.
Unfortunately, there are also those bacteria that can become dangerous or even life-threatening to us.
Those that make us sick are the so-called pathogenic bacteria. Others – the non-pathogenic bacteria – are harmless to us; they do not have the weapons to infect us and make us sick.
But to fight off the dangerous bacteria, we still need to better understand what turns a harmless bacterium into a nasty one. Thus, researchers are trying to learn more about the differences between pathogenic and non-pathogenic bacteria.
One way of doing this is by looking at bacterial families. Interestingly, even within one bacterial family, often pathogenic and non-pathogenic siblings exist together.
They often carry the same or similar genes. And yet, they have different weapons and some of these harm us while others don’t.
So, let’s look at one interesting example of a bacterial family with diverse siblings: Vibrio cholerae.
Vibrio cholerae and its good and bad siblings
Bacteria from the Vibrio cholerae family usually live on zooplankton and shellfish in brackish waters. Every once in a while, we come into contact with such a bacterium when we eat seafood or drink contaminated water. And unfortunately, some siblings of the Vibrio cholerae family can then cause very dangerous and even life-threatening diarrhoea. These are the pathogenic siblings.
But interestingly, not all siblings can infect our gastrointestinal tract. These non-pathogenic siblings do not have the right tools to infect and harm us.
Therefore, researchers have been curious about what differentiates these pathogenic and non-pathogenic siblings.
All these siblings – pathogenic or non-pathogenic – have one killer machine in common. They use a bow to fire toxic arrows into other cells. And these cells can be bacteria, amoebae or even human cells.
Not every sibling has the same set of arrows and cannot fight the same target. Hence, researchers assumed that these different sets of arrows would give Vibrio cholerae the skills to become a pathogen or not.
Vibrio cholerae uses its bow and arrow to fight off amoebae
Researchers looked at five different siblings from the Vibrio cholerae family and their fighting behaviour. Let’s call these siblings Pan, Ariel, Bobby, Chris and Danny.
These five siblings all have the same bows. Yet, they have different arrows that give them different fighting powers.
So, the five siblings use these arrows to defend themselves against enemies in the environment, other bacteria or even their own siblings. Some of these enemies are even bigger microorganisms like amoebae.
These amoebae are like human immune cells. They hunt and eat bacteria in similar ways.
Hence, some Vibrio cholerae siblings use their bows and arrows to protect themselves from amoebae. For example, the siblings Chris and Danny have arrows that they fire into the amoebae. These arrows have toxic bullets attached to them so that they can kill the amoebae.
Ariel and Bobby have the same kind of arrows, but these do not carry the toxic bullets. Since Ariel and Bobby cannot kill amoebae, researchers suggested that Chris and Danny use their toxic arrows to protect themselves from amoebae.
In comparison, Pan has the same arrow with the toxic bullets. But Pan’s bow is not active. It only gets activated under certain circumstances. Hence, when Pan faces an amoeba, it gets eaten even though it has the weapon to defend itself. Poor Pan.
Vibrio cholerae kills other bacteria with its bow and arrow
When the five siblings face other bacterial enemies, they all react in different ways. This is because they all have different arrows. Hence, they have various ways to defend themselves against bacterial enemies.
Since Pan’s bow is usually inactive, it cannot fight off bacterial enemies. Even though it has many strong arrows. It just would not fire them.
The other siblings, however, know how to use their bows and arrows. And since their arrows have different toxic bullets, they kill with different efficiencies.
It even becomes more interesting when these siblings fight each other. In these fights between siblings, the toxic bullets make the differences.
For example, the four siblings Ariel, Bobby, Chris and Danny can all kill off Pan easily. This is because Pan does not have an active bow, so it would not fire any arrows. Pan does not stand a chance against its siblings.
Ariel has very toxic bullets. And it fires them together with the arrows into its siblings to kill them.
Not Bobby. Bobby struggles with fighting off other bacteria as well as its siblings. Hence, researchers suggest that Bobby’s arrows and bullets are less toxic and thus less efficient to kill.
These types of experiments help researchers understand better how bacterial siblings can become immune to each other’s attacks.
Different powers give bacteria different advantages
Just as your special skills give you great opportunities or advantages in life, bacteria use their fighting powers to survive and thrive. They learned how to defend themselves against enemies of all kinds and families. And some of them seem to have more or less efficient ways to achieve this.
So, by learning about the defense mechanisms of bacteria, we might be able to find new and better ways to fight off the nasty bacteria ourselves. Let’s hope that one day we can fight them with their own weapons.