And more and more people become aware that a plant-based diet is not only better for your health, but also for our planet. Hence, the focus on agriculture right now is to become more sustainable to grow enough plant-based food for everyone.

This means that we need to find better ways to support plant growth and protect plants from diseases. Unfortunately, several plants pathogens make plants sick, so they die or do not grow enough crops.

Currently, we use fertilizers and pesticides to protect plants from pathogens. However, these chemicals are bad for the environment long-term as they contaminate the soil and water.

Hence, we need to find ways to protect plants by either getting rid of dangerous intruders or by strengthening the immune systems of plants.

Enter bacteria and their superpowers.

They do both.

What is biocontrol?

Some bacteria that live in or on plants are called biocontrol agents. These organisms are harmless to the plant and have two main functions: They protect the plant from pests and diseases and support its growth and crops.

Some of these organisms additionally strengthen the plant’s immune system or resistance – again to protect the plant from disease and help it grow.

One such biocontrol agent is the bacterium Pseudomonas putida. It grows near the roots of many plants where it produces helpful molecules for the plant.

And plants are clever too as they make sure that only the right types of bacteria grow near them. For this, several plants release specific molecules through their roots that help Pseudomonas putida grow. The bacterium senses these molecules so that they activate the bacterium’s chemotaxis system.

Now, Pseudomonas putida uses its flagellum to swim towards these molecules. This movement ultimately leads the bacterium to the plant that released the molecules.

Pseudomonas putida as a biocontrol agent

Once the bacterium “found” the plant, it settles down near it and starts building biofilms. Within these biofilms, the bacteria are connected with each other and with the plant. Like this, they can easily exchange molecules and information with each other and with the plant and build close relationships.

Pseudomonas putida now produces molecules to help the plant grow. For example, some molecules extend the tips of the roots so that the plant can better take up nutrients from the soil.

Pseudomonas putida also breaks down complex nutrients in the soil that the plant use. This basically feeds the plant the needed nutrients. Other molecules from the bacterium activate the overall immune system of plants so that plant pathogens have a harder time infecting the plant.

Altogether, Pseudomonas putida has similar features as biofertilizers that help plants grow.

How does bacterial biocontrol protect plants against intruders?

Pseudomonas putida can also directly fight off plant pathogens to protect their plant hosts. For this, it uses two strategies: It either holds back essential nutrients from plant pathogens or kills the intruder.

Not sure which strategy is more evil though…

Pseudomonas putida keeps essential nutrients to inhibit plant pathogens

All living organisms need iron to live and grow. And one efficient strategy to prevent other microbes from growing is by stealing iron from them.

Our immune system does it as well: All iron in our body is bound to specific transporters. Like this, no free iron swims in our blood for microbes to use. This defence mechanism is one of the first strategies of our immune systems to keep harmful bacteria from growing inside our bodies.

Similarly, Pseudomonas putida produces many different iron transporters that bind iron very efficiently. Like this, no free iron is present in the soil that other microbes could use.

Yet, this is not all. Pseudomonas putida is quite a naughty one since it can also steal iron-loaded transporters from other bacteria. This not only prevents the other bacteria from using the iron, but it also helps Pseudomonas putida grow.

Pseudomonas putida kills intruding plant pathogens

Lastly, Pseudomonas putida is a real fighter when it comes to protecting its host plant. This bacterium uses a special nanoweapon to kill plant pathogens.

Our bacterial fighter carries a bow and arrow and is not afraid of using them to keep intruders off the plant. Pseudomonas putida actively shoots arrows together with lethal toxins into other bacteria to kill them. Many bacteria use this killer machine, called the type 6 secretion system. But interestingly, Pseudomonas putida seems to have a more efficient killing device than others.

Scientists proved that with a simple experiment. When different plant pathogens were growing inside plant leaves, the leaves got sick. However, when Pseudomonas putida was additionally living in the leaves, the plant leaves did not get sick.

Finally, the scientists let the plant pathogens grow together with a Pseudomonas putida bacterium that could not shoot its bow and arrow. Now, the plant leaves got sick again and the plants suffered from the plant pathogens.

These results show that Pseudomonas putida uses its bow and arrow to actively kill other harmful bacteria to protect plants. Even though the experiment was done in plant leaves, scientists are convinced that something similar happens in the root area of plants.

Bacteria as biocontrol agent to save our planet?

As soon as we better understand how exactly this plant warden protects its host from harmful bacteria, we could use Pseudomonas putida on a large scale. This would improve the health of plants so that they can grow more and better crops.

Hence, such a biocontrol agent would eventually help us have more food available for everyone.

The post Bacterial killer weapons as biocontrol to protect plants appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

And looking at these bacterial siblings can help researchers understand the basic mechanisms of the bacterial world.

For example, some bacterial families contain both pathogenic and non-pathogenic bacteria. Pathogenic bacteria are those, that have weapons to infect us and make us sick.

On the contrary, non-pathogenic bacteria are harmless to us since they do not have these weapons.

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.

So, what is better than looking at bacterial siblings that are both pathogenic and non-pathogenic. They often carry the same or similar genes. And yet, they have different weapons and some of these harm us while others don’t.

One interesting example of a bacterial family with diverse siblings is Vibrio cholerae.

Vibrio cholerae and its good and bad bacterial siblings

Bacteria from the Vibrio cholerae family 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 cause very dangerous and even life-threatening diarrhoea. These are the pathogenic siblings.

But interestingly, not all bacterial 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 distinguishes 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 prey cells. And these cells can be bacteria, amoebae or even human cells.

Yet, within the Vibrio cholera family, 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 the siblings the skills to become a pathogen or not.

Vibrio cholerae siblings fight off amoebae with bow and arrow

Researchers looked at five siblings from the Vibrio cholerae family and their fighting behaviour. Let’s call these siblings Pan, Ariel, Bobby, Chris and Danny.

These five bacterial 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 only Chris and Danny use their toxic arrows to protect themselves from amoebae.

In comparison, Pan has the same arrow and the same 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 siblings kill bacterial opponents with bow and arrow

Next, their different arrows also help our bacterial siblings when facing bacterial enemies. All siblings react and defend themselves in different ways.

Since Pan’s bow is inactive, it cannot fight off bacterial enemies. Even though it has many strong arrows. It just does not fire them.

The other siblings, however, know how to use their bows and arrows. And since their arrows deliver different toxic bullets, they kill with different efficiencies.

It becomes more interesting when these siblings fight each other. In these family fights, the toxic bullets make the difference.

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 does not hesitate to fire them 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 how bacterial siblings are immune to each other’s attacks. And it gives them some clues about what makes a toxic truly efficient.

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 defence 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.

The post Nanoweapons make the killer differences in bacterial siblings appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

They need food, more space and are just annoyed by intruding competitors.

So, when they decide to bring out the big (tiny) killer machines, they aim to hurt their opponents badly.

One of these killer weapons is the so-called type 6 secretion system. It looks like a crossbow that sits within a bacterial cell waiting to fire lethal arrows.

And these arrows are the real deal in this killer weapon. They punch holes into the membrane of the opposing microbes and carry lethal toxins into the cell.

Here, we will focus on these arrows and how they work.

Bacteria fire lethal spikes to kill

This type 6 secretion system crossbow is made up of two parts. One part – the base – stays within the firing bacterium. You can understand this as a stem inside the bacterium.

On top of this stem sits the second part – the arrow. This arrow is ready to be fired and will actually leave the bacterium. It consists of three parts, that you can also see in the picture below:

Such an arrow has a long thin spike (red) that is connected to the stem (black). Onto this spike, different toxins (purple) are glued and hang around the arrow. On the top of the spike, the arrow has a pointy tip (pink) that pokes the membrane of the prey bacterium.

So, when bacteria shoot these type 6 secretion system arrows into other bacteria, they shoot all these different parts: the tips, the spikes and the toxins. And the toxins are what ultimately kill the prey bacteria.

Now, bacteria actually have several different proteins for these parts of the arrow lying around in their cells. And for long, it was not clear how bacteria decide how to assemble such an arrow. So, different studies looked at these different parts and how they interact with each other to better understand how bacteria build their lethal arrows.

Let’s start at the top.

A master hat protein decides for the assembly of the arrow

The protein at the very end of the arrow is called the PAAR protein. It is very sharp and has the shape of a hat. The bacterium uses this pointy end to punch a hole into the prey bacterium’s membrane.

Our bacterium of interest, Pseudomonas aeruginosa, contains seven of these hat PAAR proteins and ten different spike proteins. Generally, one PAAR protein sits on the top of one arrow spike while the spike is actually made of three VgrG proteins. So, one study looked at which of these pointy PAAR proteins belongs to which arrow spike.

To do this, researchers made different versions of the same bacterium – so-called mutants. These did not have certain hat proteins anymore so they could not kill their opponents that efficiently anymore. Also, these bacteria were unable to fire their arrows in the first place.

With these experiments, the researchers could then identify the different hat-spike pairs in Pseudomonas aeruginosa. They also learned that the PAAR protein actually determines which arrow the bacterium will fire next.

Lethal toxins stick to the spike protein

Next, the spike proteins are incredibly important since they carry the different toxins into the prey cell. And for a toxin to stick to a spike, they both have specific patches. And these patches are unique for each spike-toxin pair.

Researchers showed this by swapping the patches for the toxins between different spike proteins. They looked at the spikes G4b and G5 in the bacterium Pseudomonas aeruginosa. Usually, the G4b spike has a patch for the toxin A and the G5 spike has a patch for the toxin B.

So, Pseudomonas aeruginosa uses spike G4b to kill with toxin A and if it feels like killing with toxin B, it shoots spike G5.

The researchers then interchanged those patches. Now the G4b spike had the patch for toxin B and the G5 spike the patch for toxin A. And they showed that G4b could not fire toxin A anymore and G5 could not fire toxin B anymore.

Instead, Pseudomonas aeruginosa now fired toxin B with the G4b spike and toxin A with the G5 spike.

This helped the scientists better understand how bacteria shoot their toxins out of the cell. Another study then looked at how this patch works and how exactly the toxin is glued to the type 6 secretion system spike.

Bacteria can (sometimes!) fire spikes with random stuff

Other studies then look at whether bacteria could use random toxins and glue them to the type 6 secretion system spikes. This idea might give us tools to shoot whatever we want with this killer machine. However, in practice, it is a bit tricky.

So, researchers tried different versions of this concept in the bacterium Pseudomonas aeruginosa.

First, they took a toxin from the same bacterium but from a different part to the arrow. Instead, they glued this toxin to the spike of the bacterium and looked at whether it would fire an arrow with this toxin. Indeed, the bacterium could now shoot this new arrow into other bacteria, even though it was not as efficiently.

In a second try, they tried to patch a toxin from a different bacterium to the spike in Pseudomonas aeruginosa. This new arrow was not able to shoot that toxin into other bacteria. So, there are some limitations about how the spikes and their patches work to make toxins stick.

Understanding bacteria and their spikes for new strategies

This bacterial nanoweapon is an incredibly handy tool for bacteria. They can deliver lethal proteins into almost any organism. If we managed to understand this weapon better, we might be able to modify it and deliver whatever we want with this.

We might be able to transport therapeutics, drugs or even anti-cancerous agents. But until we’re there, still quite a bit of research is needed.

The post Bacteria fire powerful and lethal arrows to kill their competitors appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

One of these killer weapons is the so-called type 6 secretion system.

Bacteria use this nanoweapon like a crossbow to shoot toxic arrows into their foes.

And these arrows consist of extremely sharp tips, long spikes and lethal toxins.

So, when a bacterium shoots such an arrow into another bacterium, it also shoots these toxins.

However, it is still not well understood how bacteria glue these toxins to the type 6 secretion system spike.

And how do bacteria protect themselves from the lethal activity of the toxin?

A new study tried to answer exactly these questions.

The known toxins of the type 6 secretion system nanoweapon

This study focused on the pathogen Escherichia coli. This bacterium defends itself with a crossbow and a special arrow. The spike of that arrow carries a so-called lipase toxin. This toxin dissolves the membrane of its prey to kill it.

But the researchers were curious about how this lipase toxin sticks to its spike. So, the researchers looked at the spike of the arrow and found that it has a little extension. And this extension seems to work like a patch to stick to the toxin.

Other bacteria have similar patches on their type 6 secretion system spikes. And in these bacteria, the patches are necessary for the toxin to stick to the spike.

The new study found that the toxin remains inactive when it sticks to the spike protein. Nicolas Flaugnatti, the author of the study, says, that: “This data was, in my opinion, one of the most exciting of this story”. It seems that the bacterium produces the spike protein and the toxin together. But at the same time, the bacterium protects itself from the toxin’s activity.

So, after the bacterium fired the spike into the prey bacterium, the toxin needs to fall off the spike to be active. For this, Nicolas considers this scenario: maybe the spike-toxin complex hijacks a protein from the prey. This could break apart the toxin-spike complex and activate the toxin.

What does the type 6 secretion system spike look like?

Next, the researchers wanted to understand how the spike inhibits the activity of the toxin. For this, they needed to know what the type 6 secretion system spike with the toxin looks like. To see the spike, they used a special form of microscopy.

And they found that the spike complex kind of looked like a jester hat. This could mean that the spike binds three toxins and delivers all three in one firing event.

This was very exciting for everyone involved in this study. Yet, it did not explain the toxin inhibition. So, Nicolas and his colleagues asked other labs with better microscopy techniques for help. Together, they visualised the smallest details of the spike, so that now they have a high-resolution structure of it.

A structure, which the whole field was waiting for.

While the structure for the spike was already known from other bacteria, it was the first time that someone “saw” the toxin. They found that the toxin has an elongated structure and that three toxins bind around one spike.

From this, the researchers understand how exactly this toxin binds to the type 6 secretion system spike.

Great stuff.

And they saw that the spike seems to shield the toxin. Like this, it cannot bind to the membrane and break it apart.

So, this is how the bacterium protects itself from the toxin. Otherwise, the toxin would dissolve the bacterium’s own membrane.

Why do we need to know the structure of the type 6 secretion system spike?

Researchers already consider the type 6 secretion system nanoweapon a promising tool to transport proteins. However, to actually use this delivery device, we need to understand exactly how the toxin sticks to the spike.

Other studies already tried to glue other toxins to the type 6 secretion system spike. However, so far, they only knew of one of these interaction patches. It seems that having just one of these patches is not enough for a toxin to stick to its spike.

Now, that we know more details about these patches, it would be possible to engineer proteins with the right patches to stick to the spike. One possible application would be to produce probiotic bacteria that fire arrows with particular toxins to kill pathogens. 

Another idea would be to block the patches between spike and toxin. For this, it is necessary to know the structure of the type 6 secretion system spike to design specific inhibitors. Then, the bacterium would shoot blank bullets instead of toxic arrows.

Inactivating this weapon could even prevent the colonization of undesirable bacteria.

Great science makes for a great story 

Researchers learn more and more about this fascinating killer machine. While my own time studying this nanoweapon is over, I still love to follow all the news around it. 

Now that we know the structure of a toxin-loaded spike, so many questions are answered.

Problems that I could not solve, finally make sense. 

I found inner peace.

The post Understanding the type 6 secretion system spike of a bacterial killer machine appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

Especially for the killing process, bacteria have a full arsenal of killer weapons at their disposal.

They can start a chemical war, burn their foes, roll over them or punch holes into them with a bow and arrow.

But each of these decisions comes with a price; they cost energy and resources.

Especially activating and shooting killer bows and arrows is incredibly costly for a bacterium.

So, before bacteria decide to kill, they need to take their whole environment into account.

Here, we will look at when bacteria activate and engage their nanoweapon, the type 6 secretion system.

A bacterial weapon to kill when needed

Bacteria have this incredibly efficient killer T6SS weapon that looks like a crossbow with arrows. They shoot these arrows together with toxins into their foes to kill them and get rid of them.

However, you can probably imagine that bacteria can’t just fire these arrows randomly all the time. Producing the machine as well as the arrows costs a lot of energy. Hence, bacteria need to make sure they only produce and fire this weapon when it is required. Or that they gain something out the kill – like when they protect their hosts from intruders. So, they need to decide well.

Two recent studies (here and here) looked at four different bacterial species from the Vibrio genus. They focused on these bacteria because they all have very similar bacterial nanoweapons but seem to use them differently.

Also, some bacteria from the Vibrio genus can cause diseases in us or marine animals. Hence, research focuses on these bacteria to better understand them.

Two proteins control the killer weapon

Generally, bacteria from the Vibrio genus use two proteins to control when to produce their T6SS weapons. We will call these two controllers protein X and protein Y.

Interestingly, in these species, protein Y also controls the motility of the bacterial cell. So, this protein regulates how active the bacterial rotor, the flagellum, is. If it’s rotating very fast, the bacterium can swim forward. If the rotor is quiet, the bacterium stands still.

On the other hand, protein X controls an activity called competence. Bacterial competence means that the bacterium produces a special machine on the cell surface. This machine picks up free DNA from the environment. Once a bacterium takes up external DNA, it can stitch the new DNA into its own DNA. Now, this bacterium has new “powers” depending on what the new DNA is for.

These two studies looked at the links between the two controller proteins and the killing machine. And what they found, helps us better understand the bacterial lifestyle and decision-making.

Bacteria decide to kill and steal DNA

One main focus of research is on the bacterium Vibrio cholerae. This pathogen lives on seafood and can cause extremely dangerous diarrhoea in us. This is why it is important for researchers to better understand how this bacterium lives and survives in water and in the environment.

In Vibrio cholerae, both proteins X and Y control the T6SS weapon. As soon as Vibrio cholerae killed a neighbouring bacterium, protein X activates the competence machine. Now, the bacterium can take up the DNA of the dead bacterium and integrate it into its own.

With this behaviour, Vibrio cholerae not only kills competitors but also evolves. After getting rid of a foe, it gets new DNA and thus new superpowers for challenging conditions.

However, sometimes Vibrio cholerae realises it does not have a chance against its competitor. In this case, protein Y activates motility and the bacterium can swim away and escape the predator.

Bacteria decide: should I kill or should I go?

Then, both studies looked at whether the control of the T6SS weapon works similarly in other Vibrio species. They looked at these bacterial species:

• Vibrio parahaemolyticus, which causes diarrhoea and lives in seafood
• Vibrio fischeri, a squid symbiont
• Vibrio alginolyticus, another seafood-poisoning cause

All of these bacteria live in marine environments and can live in fish or seafood. Since they all cause some form of diarrhoea, researchers try to understand these bacteria better to inhibit the diarrhoea-causing mechanisms.

Both Vibrio parahaemolyticus and Vibrio alginolyticus have two T6SS weapons while Vibrio fischeri only has one. Interestingly, they are all active at different temperatures, so bacteria already control their killing activity depending on how warm or cold it is.

Also, proteins X and Y control each T6SS weapon completely differently in each bacterium. There is no pattern. None.

So, why would very similar proteins have completely different impacts on the T6SS weapons in different bacteria?

And does this mean bacteria decide differently about whether to kill or not?

There is currently no clear answer to this. So, my guess would be that it depends on the killing power of the T6SS weapon. Some T6SS weapons can kill other bacteria. Then it makes sense to activate the competence machinery at the same time. Like this, the attacker bacterium can also take up the dead bacterium’s DNA. 

However, other T6SS weapons are supposed to kill higher species, like fungi or amoeba. But a bacterium could not use the DNA of such a species. In this situation, the competence machinery is not needed. Rather, motility would be more appropriate to escape this dangerous situation.

It remains mysterious around this T6SS killer machine and how bacteria decide to kill. Or not.

The post Should I kill or should I go? Bacteria making decisions appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

The soil of the forest is full of nutrients, metals, water, oxygen and everything else a bacterium wants and needs.

However, within this paradise, there is not only one bacterium. There are thousands of them. Even more.

And each one of them wants to survive, thrive, grow and reproduce.

So, every single bacterium is making sure it is the major inhabitant of this small place in the soil.

And sometimes, there is no other way than to kill the other bacteria.

To get rid of these annoying food-stealing neighbours, bacteria have developed some fancy killing machines. They poke, they shoot, they burn or they fight.

One of these machines is even more special than the other ones. The so-called type VI secretion system is an incredibly efficient nanoweapon. It works like a bow and arrow. And here, we will find out why.

A bacterial nanoweapon as a crossbow

You can imagine the type IV secretion system as a tiny crossbow with a sharp arrow. It looks similar to the bow and arrow in the picture below.

We call our bacterium with the crossbow an attacker (this is the one in grey). When our attacker meets another bacterium that could be a danger (like the one in purple) we call this one prey.

So, our attacker bacterium has this crossbow that sits on the inside of the bacterial membrane. And the crossbow has a strong stem (in black) that holds an arrow.

And the arrow of the type IV secretion system is the real deal. It consists of three different but important parts. Each one of them makes sure the prey bacterium suffers immensely.

In most cases, the arrow is incredibly powerful. As soon as the attacker shoots the arrow into the prey, the prey dies and the attacker wins. 

So, let’s look at this in more detail.

A bacterial nanoweapon with special arrows

The arrow is clamped within the crossbow and has a very sharp tip and a long spike. The tip of the arrow is needed to punch a hole into the prey bacterium.

After the attacker punched a hole in the membrane of the prey bacterium, it delivers the whole arrow into the prey. The interesting thing is that toxins are glued to the arrow. So, when the attacker shoots the arrow into the prey, the glued toxins reach the prey as well. 

And these toxins are the real problem. They are toxic and even lethal to the prey bacterium. So, yes, our attacker came here to kill.

Generally, bacterial toxins mean to destroy essential parts in the prey bacteria. And this is how the attacker kills and wins!

Bacteria have many toxins

There is another cool thing about these attacking bacteria. Some of them have more than just one crossbow. Some bacteria have even up to six different ones. So much killing potential!

And all of these crossbows can shoot different arrows. Sometimes, bacteria have around ten different arrows lying around in their cells.

To make it even more mind-blowing: Each of these arrows has its own specific toxin glued to it. And some arrows carry multiple different toxins. 

This means, that a bacterium has many different toxins. But don’t forget that within a bacterial cell, there are a bunch of other proteins and cellular stuff.

So, how does a bacterium make sure that it fires a specific arrow with a specific toxin?

Well, both the toxin and the arrow have fitting patches. And bacteria use these patches to glue a toxin to a specific arrow.

Once arrows are loaded to their designated crossbows, they sit in the membrane and wait to be fired. So, when a bacterium meets a prey that it wants to kill, it can choose between its crossbows, arrows and toxins. Each one of these combinations seems to have an advantage under a special circumstance and against a specific prey.

And our attacker can just choose what is right at that time.

The type VI secretion system – a truly special bacterial nanoweapon

Currently, scientists are working hard to understand exactly how this fascinating bacterial nanoweapon works. One goal is then to use this killer machine in other applications.

For example, one aim of researchers is to have a tool to kill bacteria that we cannot fight with commercial antibiotics anymore. Another idea is that we better understand how toxins glue to the arrow so that we can create bacteria that deliver therapeutics, vaccines or other drugs.

So, let’s see what future research into this amazing bacterial nanoweapon will bring us.

The post A bacterial nanoweapon called the type 6 secretion system appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world