And only thanks to pigments, life on Earth is possible. Pigments were the first molecules that microbes used to harvest sunlight. Microbes could then transform the light energy into chemical energy and produce oxygen.

Even the brown-reddish haemoglobin in your blood is an essential pigment as it transports oxygen within your body. Also for bacteria, pigments and their colours have life-saving functions. Here, we will look at how biopigments colour the bacterial world and what bacteria gain from producing them.

Bacterial pigments bring colour to the world of bacteria

Biopigments are molecules with complex chemical structures and at least one excited electron. Depending on the electron’s arrangement, a pigment absorbs light at a specific wavelength. It reflects the colour of the unabsorbed wavelength, which gives the pigment its colour.

As the function of pigments depends on the incoming light, sunlight plays a crucial role for bacteria with pigments. By adding certain pigments to their membrane, bacteria can adapt to environments that are directly affected by sunlight or the lack of it. This gives them an advantage over those bacteria that lack these pigments.

However, some bacteria also use pigments for other purposes, which we discuss further in this article.

Microbes harness photosynthetic power with colourful pigments

Sunlight is incredibly powerful since each light photon contains energy. Bacteria adapted to harvest energy from sunlight with special pigments.

Pigments can capture the incoming photon and transfer its energy to other molecules. This process transforms the incoming light energy into chemical energy. So-called phototrophic microbes are those that gain their energy from light.

The best-known example of a photosynthetic biopigment is chlorophyll in plants, algae and cyanobacteria. Cyanobacteria produce several complexes of bacteriochlorophylls to absorb blue and red light. As the green light is not absorbed, it is reflected, which is why chlorophyll – and thus cyanobacteria, algae and plants – are green.

Some bacteria harvest more light by producing several pigments of different types. They then arrange them in an optimal formation according to the incoming light.

For example, carotenoids capture energy in the green-blueish range and pass it on to the associated chlorophyll. Together, these photosynthetic complexes absorb light energy from almost the entire wavelength spectrum.

Halophilic bacteria and archaea are microbes that produce carotenoids to capture sunlight. You may have seen salt ponds with a reddish colour. This comes from the red and pink-coloured archaea Halobacteria, bacteria Salinibacter or algae Dunaliella. Thanks to their colourful carotenoids, these microbes adapt to salty waters that are exposed to direct sunlight.

Cyanobacteria in the deep sea, lagoons, lakes, ponds or rivers produce similar molecules to chlorophyll. These absorb the blue-green light in water, which allows these bacteria to survive in these dark environments. If you have ever seen a lagoon shining yellow or orange, this was probably due to the colourful cyanobacteria inside.

Bacterial biopigments protect from too much light

As light is full of energy, bacteria also need to protect themselves from getting burned. For this, they produce pigments that take up the excess light energy. Like this, the main photosynthetic complex does not get damaged.

Carotenoids and xanthomonadins are the colourful sun blockers of the microbial world. These molecules absorb high-energy light to protect chlorophyll from damage. Over 600 different carotenoids were described and they usually come in yellow-orange-reddish colours.

The yellow xanthomonadins absorb wavelengths within the energy-rich UV spectrum. Bacteria like Xanthomonas campestris live on plant leaves where they are exposed to direct sunlight. Hence, their yellow xanthomonadin coats are like self-made sunblocks protecting the bacteria.

Also, the pigment melanin shields the producing cell from energy-rich sunlight. Many bacteria living in the soil or bacterial spores produce these pigments. Here, melanin absorbs light from a wide range of the light spectrum to protect the inner of the cell. Hence, melanin-producing bacteria, like Vibrio cholerae and Streptomyces bacteria, are brown or black.

Bacterial pigments let electrons flow and save energy

Since bacterial pigments allow electrons to flow, they can also be energy conductors. Hence, some pigments are important components of energy complexes and synthesis machineries.

For example, yellow flavins are pigments involved in cellular metabolism. The main flavin is riboflavin, which you may know as vitamin B12. This essential molecule – produced only by bacteria – allows our bodies to work.

Phenazines are unique bacterial pigments with yellowish-green fluorescent colours. Pyocyanin, exclusively produced by Pseudomonas bacteria, shuttles electrons – and thus energy – during the respiration process. Hence, pyocyanin is essential for Pseudomonas as it keeps the bacteria healthy and alive.

Some biopigments have anti-oxidant effects

Bacterial pigments don’t just help adapt to external environmental conditions like the sunlight. They also guard the inner bacterial cell from stressful situations.

Excess or uncaptured energy or escaped light photons can react with oxygen. This process produces so-called oxygen radicals, which can damage molecules inside the bacterium. Known as oxidative stress, oxygen radicals can even become life-threatening for bacteria.

Carotenoids and xanthomonadins protect bacterial cells from oxidative stress. These pigments transform the free oxygen radicals into harmless molecules. Since carotenoids and their product vitamin A have similar functions in humans, it is only healthy for us to take up a lot of these with our diet.

In the bacterium Gemmatimonas aurantiaca, orange carotenoids also work like sunscreen and oxidative shield. These pigments both give the bacterium its bright orange colour and protect it from too much sunlight.

Bacteria combat microbial enemies with coloured pigments

As night falls, many bacterial pigments reveal their darker sides. They become important weapons for microbial warfare. Without sunlight, several pigments take on roles as virulence factors and antimicrobials as they mess up cells’ energy and oxygen household.

For example, prodigiosin is the red weapon of Serratia marcescens. As prodigiosin inhibits the growth of several bacterial, fungal and insecticidal pathogens, Serratia marcescens is an important biocontrol bacterium of plant disease.

You may have seen prodigiosin-producing Serratia bacteria on contaminated food. They develop these red, blood-like dots.

Violacein is a purple pigment with anti-viral, anti-bacterial and anti-cancer properties. For example, Chromobacterium violaceum sends membrane bubbles filled with violacein to kill bacterial enemies.

Similarly, Janthinobacterium lividum protects frogs and salamanders as it lives on their skins. Here, the bacterium throws violacein at pathogenic fungi that would otherwise infect and harm the animals.

Pyocyanin, the fluorescent electron-shuttling pigment in Pseudomonas, is also very sensitive to oxygen. It even turns Pseudomonas aeruginosa cultures in the lab blueish just by shaking and airing them.

Yet, not all bacteria have an appropriate coping mechanism for pyocyanin. Hence, these bacteria suffer oxidative stress when they come into contact with this pigment. This is why Pseudomonas uses pyocyanin also to fight bacterial and fungal enemies.

Vivid pigments colour the bacterial world

The Bacterial World is colourful – one of this blog’s taglines. You may have asked yourself what this is about and why bacteria have so many different colours.

From the dazzling pink of halophilic microorganisms to the sunny yellow of phytopathogens, bacterial pigments give their producers shiny and vibrant colours. But thanks to the colourful biopigments, bacteria also gain abilities to survive in new and challenging environments.

Some of these bacterial pigments are essential for us humans and even life on Earth. From some of these colourful biopigments, we produce vitamins that we need for our own metabolism. Also, every oxygen molecule that you just took up with your last breath, at some point, was transformed by a bacterial chlorophyll pigment.

So, I guess it is yet again time to be grateful to bacteria and their vibrant and life-enabling activities!

The post Creating the colours of the rainbow: Bacteria and the vibrant world of pigments appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

Energy to grow, to move, to fight, to produce stuff and also to reproduce.

Generally, living organisms get this energy from food. It fuels us, just as it fuels animals, plants and bacteria.

But where exactly is this energy in food? How do bacteria and other living organisms access this energy? And what do they do if their favourite food is not around?

To answer these questions, let’s look at how molecules store energy.

How do living organisms gain energy?

Each chemical bond between atoms contains energy. Hence, a molecule that is made of many atoms and thus many chemical bonds, contains energy. When such a chemical bond opens, it releases energy in the form of electrons.

Depending on the kind of chemical bond within the molecule, these electrons can have higher or lower energy levels. Thus, they contain more or less energy.

So, to obtain energy from molecules, organisms need to break apart molecules and extract the electrons with high energy. But this is not as easy as it sounds. Chemical bonds are quite tight and it actually requires energy to break them open.

Hence, organisms need to have the right sets of proteins that can break open specific chemical bonds in molecules. These kinds of proteins are called enzymes. So, only if an organism has enzymes to break apart glucose, it can use glucose to extract its electrons and obtain energy.

Interestingly, most organisms do exactly that. They break apart glucose into smaller products and take the freed electrons. In that case, glucose is the so-called electron donor.

Now, these electrons need to go somewhere, since they are full of energy. So, organisms save this energy by transferring these electrons onto other molecules. These molecules have lower energy levels, hence they like to take up electrons. We call these molecules electron acceptors.

But finding the right electron acceptor is not as easy as it sounds.

The many steps from an electron donor to an electron acceptor

Imagine you stand on a high wall and want to get down onto the ground. You could take one big jump to reach the ground. But then you would risk that this high fall would give you so much energy that you might break your knees.

So, you could take a set of stairs, that brings you to the ground in multiple steps. Each step only releases a small chunk of energy but they would definitely not hurt you.

It is the same with electrons from donors with a lot of energy. Transferring these electrons to a final electron acceptor would free up too much energy at once. This could actually burn a cell. Hence, organisms transfer these electrons onto intermediate electron acceptors.

Each of these transfer steps only releases a small chunk of energy that keep organisms warm but also fuel cellular processes. In bacteria, these transfer processes happen in their membranes, where the released energy is directly used.

Here, the released electrons energise flagella so that bacteria can swim. Electrons can also activate transporters so that bacteria can import or export stuff. Not needed electrons and their energies are stored in energy-saving molecules like ATP.

This whole process of electron transfer from a donor to its final acceptor is generally what researchers call cellular or – more specifically – bacterial respiration.

Which molecules do bacteria use for cellular respiration?

Cellular respiration fuels most living organisms. And glucose is a molecule with one of the highest energy levels. Hence, breaking down glucose to extract its electrons is the most common in living organisms.

Animals do it. Fungi do it. So, bacteria are no exception to it.

And as a final electron acceptor, most organisms use oxygen. This molecule has a very low energy level and is basically everywhere so most organisms transfer their electrons to it.

This is what we call aerobic respiration (which is what we generally do as well). But it comes with great risk.

The downside of aerobic bacterial respiration

As soon as an oxygen molecule is fuelled with just one electron, it becomes hyperreactive. Such a semi-activated oxygen molecule can basically react with any compound in a cell and damage it.

This is what makes aerobic respiration quite dangerous. So, every organism aims to hide these reactive oxygen molecules in the membrane.

Yet, it can happen that such a reactive oxygen molecule escapes the membrane. In this case, a special protein binds it and breaks it apart. So, every organism that does aerobic respiration has this same kind of protective protein to get rid of reactive oxygen molecules.

This means that whenever scientists find a new microbe, they first test whether this new microbe has these proteins. To test this, they add a bit of hydrogen peroxide to the bacterial colony. When bubbles come out of the bacteria, it means that they do aerobic respiration. In this case, they have the enzymes to break apart the reactive oxygen molecule and produce oxygen from it.

Which other molecules can bacteria use as energy source?

As we said, most bacteria use glucose as an energy source for cellular respiration. However, there are also many fancy exceptions. And these exceptions make the bacterial – and microbial – world so colourful and diverse.

While many bacteria can extract electrons from many different organic acids and amino acids, some use sulphur compounds. Some bacteria also break apart greenhouse gases like methane, carbon monoxide or even hydrogen gas. Since these bacteria might be helpful in tackling our climate problems, they are of particular interest to researchers!

What does bacterial respiration look like without oxygen?

We surely need our oxygen for respiration. Yet, many bacteria and fungi can live with only small amounts of it or even no oxygen at all.

In this case, they do anaerobic respiration. This basically means that they don’t transfer their electrons to oxygen as an electron acceptor.

Instead, many bacteria have enzymes to transfer their electrons to different electron acceptors. And these depend on what the bacteria have available around them. These electron acceptors can be nitrate or sulphate compounds, salts like arsenate or even metals like iron and gold.

Also, in many microbes, anaerobic respiration is closely related to microbial fermentation. In this case, the bacteria break apart glucose but produce molecules that do not require oxygen.

Just think about yeast that produces ethanol in beer and wine. Or lactic acid bacteria in your sauerkraut and yoghurt that produce lactic acid to make the food more acidic. Lastly, there are fungi like Zymomonas mobilis that produce huge amounts of ethanol from glucose.

Bacterial respiration makes the microbial world diverse

As we have seen, bacteria learned to use various sources to gain energy. They created the right enzymes to extract electrons from fancy high-energy molecules.

And then they learned to transfer these electrons onto even fancier molecules to gain the most energy. Some of these processes even involve bacteria producing shiny gold!

In my opinion, these truly amazing superpowers make the bacterial world so incredibly colourful and fascinating!

The post How bacteria gain energy from cellular respiration to fuel life appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

Also, bacteria want to grow and flourish and reproduce. But they are only single cells so that their way of reproduction is unique. They reproduce asexually meaning you only need one parent bacterium to make two daughter bacteria.

When you think about it, bacterial cell division seems very easy: Start with one bacterium, divide it in the middle and you end up with two.

However, the mechanism of cell division is pretty complex and involves at least three tasks:

• the bacterium needs to decide WHERE to divide
• get all the needed machinery to the division site
• produce new cell envelope material to separate the two new daughter cells

How a bacterium starts cell division

As you can imagine, for most bacteria it makes the most sense to divide straight in the middle. Like this, they end up with two daughter cells of the same size.

This means a bacterium needs to find its middle and mark it. While it is not completely clear yet to researchers how bacteria find the exact middle, they know it involves a so-called Z-protein.

This Z-protein can bind two things: itself and the inside of the bacterial cell envelope. But it only binds the cell envelope where it is straight and not bent. And this is only the case in the middle of the bacterial cell envelope.

Hence, the Z-proteins bind themselves in a long chain linked to the straight cell envelope. Eventually, they form a ring on the inside of a bacterial cell. And this so-called Z-ring stays in the middle of the bacterium.

Also, the Z-ring is only stable when bacteria have enough nutrients and do not encounter any stress situations. This reassures that bacteria only divide when they have all the needed supplies.

How bacteria divide and produce two daughter cells

Once this Z-ring is stable, it recruits helper machineries to this now defined division site.

The Z-ring is a sign of an upcoming cell division. Now, the bacterium knows it needs to activate machineries to produce more cell envelope material and become longer. And to increase their cell envelopes, bacteria use ferries, tunnels and bridges to transport lipids into the cell envelope.

Like this, the bacterium becomes longer and can start the actual cell division. At the same time, the Z-ring becomes tighter and the cell envelope gets its natural bend again.

Now, two processes happen at the same time: Bacteria cut open their peptidoglycan envelope to separate the two daughter cells and also produce envelope material to close both cells.

After this happened, we have two daughter cells coming from the same parent. They both share the same cell envelope and genome. This is why we consider them identical twins.

But do all bacteria produce identical twins upon cell division?

Do bacteria always divide in the middle and produce identical daughter cells?

Yes, most bacteria are symmetrical. And when they divide right in the middle, they produce two identical daughter cells.

Researchers could even watch bacteria during this process thanks to amazing microscopy techniques. You can see the single stages of bacterial cell division and how bacteria produce the cell envelope in the image below.

Yet, the bacterium Caulobacter crescentus has two different cell ends. It can stick to a surface with its sticky stalk on one end and have flagella on the other.

This bacterium also starts cell division in the middle like what we discussed above. However, the new daughter cells are now different: one is still glued to the surface and the other one has flagella and can swim away.

Also, the bacterium Helicobacter pylori with its helical shape can never really find its perfect middle. Hence, the Z-ring forms somewhere inside the bacterium and its daughter cells always have different sizes.

And then there are funny bacteria that decided they don’t even need to divide in the middle. Bacteria like Gemmatimonas aurantiaca grow “budding” daughter cells out of their own parent cells. However, researchers don’t understand yet why this bacterium chooses to divide in this asymmetric way.

Another way of asymmetric cell division happens in the bacterium Bacillus subtilis when it produces spores. During the sporulation process, the spore daughter cell grows within the mother cell. In the end, the mother cell bursts to release the spore into the environment. In this case, only one daughter cell comes out of the division process.

Why and how we want to prevent bacteria from dividing

Since cell division is an essential mechanism for bacteria, nature also found ways to inhibit it. Many antibiotics or toxins inhibit the production of cell envelope material or of the Z-ring. Like this, bacteria cannot divide anymore; they cannot grow and die.

However, we also know that some bacteria can find ways around the toxicities of antibiotics or toxins and become resistant to them. Hence, by better understanding how the whole mechanism works, researchers can hopefully find new ways to interfere with bacterial growth and find new weapons in the fight against antimicrobial resistance.

The post Why bacteria divide into two and grow with the help of a strong ring appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

For a virus to survive, it needs another living organism. Viruses infect any organism that has its own metabolism: animals, humans, fungi or even bacteria.

But none of these organisms likes being infected by a virus. It makes them sick.

Therefore, each organism developed its own way to fight off viruses. For example, you have your immune system that is trying to protect you from bad viruses.

And so do bacteria.

The bacterial immune system is not as complex and sophisticated as ours. But still, bacteria developed several mechanisms to fight off viruses and protect the community.

Here, we will look at the different ways of how bacteria become immune to viruses.

How a virus infects a bacterium

First, let’s have a look at how a virus infects a bacterium and reproduces.

Most viruses can only infect one specific bacterium. This is because each bacterium has a slightly different coat around its cell. And viruses recognise specific components on the outside of these coats.

When a virus binds to such a specific component on the bacterium, it cuts a little hole into the coat. Now, the virus can inject its genome through the hole into the bacterium.

The bacterium recognises the genome and starts producing virus particles from the viral genome.

After the bacterium produced many virus particles and they assembled into full viruses, the bacterium bursts and dies. This releases the produced viruses from the bacterium. The viruses now spread and infect other bacteria and the cycle begins again.

How bacteria fight off viruses

Each infected bacterium is a risk to the whole bacterial community. An infected bacterium produces many viruses that can infect many more bacteria in a community.

This is why, bacteria developed several ways to defend themselves against viruses. And many bacteria use different modes of defence against viral attacks.

So, what does a bacterium do to defend itself against viruses?

Preventing the virus from binding

The first line of defence against a viral intruder is to prevent a virus from binding to the coat of the bacterium.

A virus recognises and binds to a specific component on the coat of the bacterium. So, a bacterium can mutate this component and change it to prevent the virus from binding.

Another option is for the bacterium to produce biofilm. Biofilm is a slime that covers the bacterium and all its bacterial friends and protects them from harmful components like antibiotics, chemicals and viruses.

Sending out bacterial decoys

A really smart way of bacteria is to mislead viruses. Bacteria can produce bubbles from their coats that still contain the specific components that viruses bind to.

A virus can bind to these specific components and infect the bubbles. But the bubbles do not contain machines to produce viruses. Therefore, the bacterium does not get infected and will not produce any viruses.

Smart bacteria!

Destroying what is coming in

After a virus attached to a bacterium, the actual infection starts when a virus injects its genome into the bacterium. This can be DNA or RNA.

Some of our little bacterial friends developed smart devices to recognise any DNA or RNA that does not belong to the bacteria. When a bacterium “sees” viral DNA or RNA inside the cell, it activates huge destruction machineries. These work like scissors and cut viral DNA or RNA into tiny pieces to make them non-functional. Now, the bacterium will not even start producing viral components.

Many bacteria have different kinds of anti-viral scissors. And each one machinery recognises and cuts one specific piece of viral DNA or RNA.

The interesting thing is that bacteria use these scissors also to learn to fight new viruses. With the so-called CRISPR-Cas system, a bacterium learns to recognise new pieces of viral DNA or RNA when it first “sees” it. The next time the bacterium is infected with that same virus, it already knows how to fight it.

This is similar to how our body learns to fight a virus after we gave it a vaccine. We show our bodies what a certain virus looks like and it can develop the right weapons against it. The next time this virus attacks our body, we already have powerful weapons to fight the intruding virus.

Inhibiting the viral genome

If a virus was indeed successful and injected its DNA or RNA into a bacterium, some bacteria can still handle this. In this case, the bacterium produces specific molecules that bind to the viral DNA and prevent it from functioning properly.

This prevents the bacterium from producing viral components from the viral genome.

If nothing else works there is still one way out

Imagine, a virus was indeed lucky and managed to inject its DNA or RNA into a bacterium. And then imagine, the bacterium did not destroy the viral DNA or RNA and it produced viral components.

Now, the bacterium needs to prevent that these particles assemble into full viruses so that it does not kill the bacterium and spread into the surrounding.

In this case, bacteria have one last line of defence. And this defence mechanism is a truly altruistic weapon: Kill itself to protect the others.

Yes, an infected bacterium is prepared to sacrifice itself so that the whole community survives.

Just before virus particles assemble to full viruses, a bacterium can activate a suicidal mechanism. Like this, no full viruses will be released into the surrounding. No other bacteria will get infected with this virus. Everyone is safe.

Because bacterial suicide is such a drastic mechanism, bacteria only activate it after all other defence mechanisms failed.

Multiple lines of defence to protect the whole community

As you can see, bacteria developed several ways to protect themselves from viral attacks.

Don’t forget that also viruses mutate and can become resistant to any of these mechanisms. So it is a constant microscopic war between all the different microbial players.

Interestingly, not one bacterium has all the described mechanisms and is perfectly protected. But each bacterium has a few of these anti-viral weapons. Therefore, by working together, the whole bacterial community knows how to fight off most viruses. This teamwork can indeed protect the whole community.

How much we can learn from our microbial friends about how to fight off nasty viruses :)

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Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

Many of our organs have a slimy mucus which is supposed to stop bacteria from entering the human body. But some bacteria developed mechanisms to swim through this gel-like mucus faster than others.

And these bacteria are usually the ones that make us super sick.

Meet the bacterial race swimmer Campylobacter jejuni

The pathogenic bacterium Campylobacter jejuni for example causes food-poisoning and watery diarrhoea. And this pathogen can swim through gel-like slimes, like the mucus in our bodies. Other bacteria are slowed down by this slime, but not Campylobacter jejuni. It even swims faster when it hits slime!

Why is that?

Well, that is exactly what researchers were trying to find out.

Two flagella for one movement

Campylobacter jejuni looks pretty cool. It has a helical shape and one flagellum on each side of the cell. Flagella are like fine hair that grow out of the bacterium. 

Closer to the membrane of the bacterium, the flagellum becomes a so-called hook. This hook is connected to a little motor inside the bacterium. And this motor rotates, which then rotates the hook and thus the flagellum. Now, the flagellum works as helical propeller and this movement pushes the bacterium forward so that it swims.

Since Campylobacteria jejuni has two flagella of different length, researchers were curious about how this bacterium would move. Two motors would constantly push the bacterium in the opposite direction. Plus, they saw previously that this bacterium can swim faster than other bacteria in slime. But they had no idea how these two flagella would work together. 

Wrapped in flagella

To see the flagella under the microscope, they changed them slightly. Like this, they could stain the flagella and see them as yellow fluorescent tails under the microscope.

They saw that in watery liquids, half of the bacteria had both their flagella spread to both sides and they were swimming slowly. This you can see on the left side in this video. The other half had one flagellum rotating as a tail at the back and the other flagellum was wrapped around the bacterial cell.

In gels (in the video on the right) almost all the bacteria (>95%) had one of their flagella wrapped around their cells. Plus, these cells swam faster and more directed. Mind-blowing!

Two motors are better than one

So, the researchers wanted to know why Campylobacter jejuni wraps the flagellum at the front around its cell and how that helps the bacterium to swim faster. They created two mutants of this bacterium: One bacterium did not have a front-flagellum and the other did not have a tail-flagellum. 

And they looked at how these mutants swam in comparison to the bacterium that has two flagella. In the video below, you can see the bacterium with two flagella on the left, the bacterium with the tail-flagellum in the middle and the bacterium with the front-flagellum on the right.

And as you can see, the bacteria in the middle had their tail-flagellum propelling. This pushes the bacterium forward so that it swims. Bacteria with the front-flagellum still swam. And the researchers confirmed that this front-flagellum is still rotating. It works as if it drills the bacterium forward.

So, when bacteria have two flagella, it has double the power; and the pushing and drilling together makes this bacterium super fast.

Changing direction

Next, the group was interested to see how Campylobacter jejuni changes its swimming direction. Luckily, they managed to film one bacteria at the moment when it decided to swim towards the other side.

In this video, you can see that first the front-flagellum changes the direction of its rotation. Like this, it is getting unwrapped from the bacterium.

Then, the tail-flagellum also changes its direction of rotation and the bacterium halts its movement. This looks as if the bacterium tumbles trying to get to the new direction.

Next, the former tail-flagellum wraps around the bacterium and becomes the front-flagellum.

And the former front-flagellum becomes the tail-flagellum and rotates to push the bacterium towards the opposite direction.

Two flagella to get to the perfect location

Researchers already knew that other bacteria also wrap their flagella around their cells. But often this happens in trapped places so that the bacterium tries to protect its flagellum. However, Campylobacter jejuni with its two flagella developed some efficient mechanisms to infect the human body. 

• Its helical shape helps the bacterium to drill through slimy mucus

• A rotating front-flagellum pulls the bacterium actively forward helping with the drilling movement of the bacterium

• The tail-flagellum rotates to propel the bacterium forward

• By quickly changing its swimming direction, Campylobacter jejuni can escape from confined spaces or maybe even immune cells in the human body

I’m always amazed by what bacteria come up with to escape dangerous situations…

So, now that we better understand how this pathogen moves in our bodies, we better understand how it infects us. This knowledge will now help to fight this pathogen. Let’s hope that it will help us get rid of such nasty food-poisoning-causing bacteria. 

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Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

They don’t have eyes to see what is going on.

Neither do they have ears to hear a foe approaching.

And yet they seem to know exactly what is happening around them.

How is that possible?

In other articles, we already looked at different mechanisms of how bacteria sense their environment. And we learned about various ways bacteria use to know what is going on around them.

Here, we will look at another one of these mechanisms. A mechanism in which bacteria destroy proteins to understand the environment and adapt to it.

But before we can look at why bacteria destroy proteins, we first need to understand how bacteria produce proteins.

Bacteria need proteins to produce proteins

Every living cell, like a bacterial cell or a human cell, contains DNA. And the DNA contains many different sections, which are genes. These genes are the templates for ALL proteins that a cell can produce.

A cellular machine called the polymerase (bright blue in the figure below) recognizes the start of a gene (yellow), before it transcribes this gene into a string of mRNA (grey). Next, a ribosome reads the mRNA fragment and translates it into a protein (yellow).

This is how every living cell produces proteins from DNA.

Now, we will focus on the first step: when the polymerase recognizes the start of a gene.

Bacteria need proteins to regulate protein production

When you think about it, bacteria do not always need all genes and all proteins. Just as you don’t need an umbrella when it is sunny outside, but it is always good to keep it handy. Similarly, bacteria have heaps of genes on that long string of DNA and they need some of them only under certain circumstances.

For this, all living cells have regulators. These regulators make sure that the polymerase only produces mRNA from genes that are required at a specific time point.

And these regulators come in two forms: activators and repressors.

Activators activate genes

Sometimes, the polymerase cannot recognize a specific gene on its own. This is when the polymerase needs an activator (green). 

An activator is a protein that binds to a specific gene only when needed. This attracts the polymerase to this gene so that it produces mRNA from that gene. Like that, an activator ensures that bacteria only produce certain proteins when needed.

This means something else needs to activate the activator at a specific time point. And while some activators are activated by specific systems as explained in How bacteria sense their environment, sometimes protein-destroying systems are involved. More about that below.

Repressors deactivate genes

Repressors (dark blue) do exactly the opposite of activators. These proteins bind specific genes right at the start. This blocks the polymerase from binding the start of that gene and from producing mRNA.

But when the bacterium needs a specific protein, the polymerase has to recognize and bind that specific gene. At that point, the bacterium has to get rid of the repressor.

So, let’s have a look at how bacteria gain access to genes that need activators or are blocked by repressors.

Bacteria destroy proteins to understand the environment

The environment constantly changes for a bacterium. So, all the time, a bacterium needs to produce certain proteins to handle these new situations. Just as you take your umbrella when it is raining suddenly.

This is when the bacterium needs the polymerase to recognize a specific gene to make mRNA from it.

To get rid of a repressor or to activate an activator when needed, bacteria came up with a simple mechanism: protein destruction.

Yes, to produce proteins, sometimes bacteria destroy proteins.

Proteins that destroy proteins are called proteases and these work like molecular scissors. Proteases cut proteins in at least one specific location. This makes the protein fall apart and become kaput. 

When do bacteria destroy proteins?

Different bacteria developed various mechanisms when to destroy specific proteins. And researchers start to understand more and more about this way of regulation.

So, let’s have a look at a few cool examples of bacteria destroying proteins.

Radiation leads to protein destruction and survival

For example, the fascinating bacterium Deinococcus deserti has genes to cope with radiation and desiccation. However, the bacterium does not need to produce these proteins when there is no radiation or desiccation.

Under these circumstances, the repressor D (dark blue in the figure below) blocks these genes and makes sure the polymerase cannot recognize them.

But as soon as the bacterium is hit with radiation (lightning), the radiation activates the protease M (red). This protease can now bind the repressor D and destroy it. Now, that the repressor does not block the radiation genes anymore, the polymerase can recognize the genes and produce mRNA from them. Now, the ribosome produces proteins (yellow) that cope with the radiation. 

And this is how the bacterium Deinococcus deserti destroys proteins to survive. And yes, this bacterium has the superpowers to withstand radiation and desiccation like no other bacterium.

Antibiotics lead to protein destruction and resistance

In another example, Staphylococcus aureus has a similar mechanism to cope with antibiotics and become resistant. 

In the membrane of this bacterium sits the protease R (red) that is generally inactive. However, when the bacterium meets antibiotics (green molecules), the antibiotics change R. 

Now, the protease falls into the inside of the bacterium and destroys its target protein. This is the repressor I (dark blue), which sits and blocks a certain gene. After protease R destroyed repressor I, this gene is unblocked and the bacterium produces a protein (yellow) that cleaves the antibiotic. 

And this is how Staphylococcus aureus becomes resistant to antibiotics by destroying proteins.

Heat leads to protein destruction and survival

But bacteria do not only destroy repressors. They also use a similar mechanism to activate their activators. 

Generally, to keep an activator inactive, another protein is involved. This is the so-called anti-activator since it captures the activator and inhibits it from functioning. So, for the activator to become active and to bind its specific gene, the anti-activator needs to go. And this is exactly what bacteria do.

For example, in the soil bacterium Bacillus subtilis, the anti-activator Y (dark blue) captures the activator S (green). Plus, Y brings S to the cellular garbage machine (purple) to destroy this protein.

However, as soon as it is getting too hot for the bacterium, Y becomes unstable. So unstable, that it cannot hold S anymore. This means S gets freed, binds its favorite genes and leads the polymerase to them. Now, the bacterium produces proteins (yellow) that help the bacterium to cope with the damage from the heat.

And this is how Bacillus subtilis destroys proteins to cope with heat.

Destroying proteins means bacteria can survive

Here we explored three different ways of how bacteria destroy proteins for their own benefit. Interestingly, the benefit always handles the incoming signal which is often a sign of stress.

Like in Deinococcus deserti, radiation activates protein destruction that leads to protein production. And these new proteins now handle the damage after the radiation attack.

Or in Staphylococcus aureus; antibiotics activate a specific protease that destroys a repressor. Now, the produced proteins are meant to destroy the harmful antibiotics.

So by closing these circles, bacteria found efficient ways of how to read their environment and adapt to it.

Interestingly, most bacteria seem to use similar mechanisms. This means, the better we understand the way most bacteria work, the better chances we have to fight the nasty ones. So we need to keep researching the good bacteria, to understand the bad guys too!

The post Bacteria destroy proteins to understand the environment appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

What is bacterial sporulation?

When a bacterium sporulates, it transforms from a rod-shaped bacterial cell (4-10 μm long) to a round, spherical spore (1-1.5 μm long).

Bacterial spores are surrounded by thick layers of cell wall material or peptidoglycan and many layers of proteins. These make the spore highly resilient and shield it from all kinds of environmental assaults, including UV radiation, desiccation and antibiotics. Within the spore, it protects the genetic material of the parent bacterium.

Now the spore is metabolically dormant. This means that the cell has stopped all activities which require energy, like growth and development.

Spores can remain stable for extremely long periods of time. In fact, researchers found Bacillus spores dating back almost 25 million years in the abdomen of extinct bees preserved in Dominican amber. Other samples date back 250 million years from salt crystals.

Why study sporulation?

To date, most studies aim to understand sporulation in the model bacterium Bacillus subtilis. Bacillus subtilis is a Gram-positive bacterium with a thick layer of peptidoglycan outside the cellular membrane.

One of the major reasons why is it relatively easy to study sporulation in Bacillus subtilis is its natural ability to take up foreign DNA and integrate it into its genome. This provides scientists with a wide range of tools for gene editing in Bacillus subtilis. And they can study the functions of different molecules in space and time during sporulation.

Some bacterial spore-formers can also be pathogenic in a human or animal host.

Examples include Bacillus anthracis (the causative agent of anthrax), Clostridium difficile (implicated in colon disease) and Clostridiumm botulinum (implicated in food poisoning). Spores of these pathogenic bacteria can secretly survive inside the host due to their ability to withstand harsh environments. But once they get access to nutrients, they germinate again and become viable bacteria. These bacteria can then release lethal toxins to cause diseases in their respective hosts.

There is some good news for the food lovers too though! Spores of a strain of Bacillus subtilis, Bacillus subtilis (natto) are used to ferment soybeans in a traditional Japanese dish called natto. The critical process in natto preparation is the germination of spores which then use nutrients from the soybeans to ferment them. The dish with its powerful smell and flavor is definitely for the bold!

How does sporulation work?

Normally, a bacterial cell divides in the middle to produce two identical daughter cells. Researchers call this process binary fission or vegetative growth.

But when a bacterium sporulates, the cell divides closer to one end of the cell, near a pole. This leads to the formation of two daughter cells of different sizes. The smaller cell is the forespore and the larger cell is the mother cell.

The two cells are separated by a wall made by the invagination of the cell membrane and the peptidoglycan. This wall is the septum.

Cell division leads to separation between spore and mother cell

Surprisingly, the wall separating the two daughter cells is almost four times thinner during sporulation than during vegetative growth (~22 nm vs ~80 nm).

Scientists have always wondered why the cell would need a thinner septum during sporulation. One reason can be that the forespore and the mother cell need to communicate with each other and exchange certain metabolites. A thinner septum can make this a lot easier because channels don’t have to go through a thick wall.

Another reason could be that the thinner septum is likely more flexible and easier to bend and stretch. Hence, the mother cell can move forward to engulf the forespore so that it is completely inside the mother cell.

Transporting DNA into the spore

When a bacterial cell divides vegetatively, it splits the bacterial DNA equally into two daughter cells.  But an interesting phenomenon occurs during sporulation.

The DNA is trapped at the septum such that the forespore has only 1/3^rd of the DNA and the remaining 2/3^rd stays in the mother cell. A transporter then pumps the rest of the DNA from the mother cell to the forespore.

Packing the whole DNA into the small volume of the forespore probably increases the turgor pressure in the forespore. Hence, the forespore inflates like air in a balloon to give it an ovoid shape.

Bringing the spore inside the mother cell

A critical process during endospore formation is when the mother cell engulfs the forespore. This means that instead of lying side by side, the forespore is now within the mother cell.

To engulf the forespore, the mother cell has to overcome two barriers:

(1) the peptidoglycan that surrounds the bacterial cell on the outside (shown by blue circles in the figure below), and

(2) the septum (also peptidoglycan) that separates the two cells (shown by green circles in the figure below).

But the septum and the bacterial cell envelope are also connected. At this so-called leading-edge the two peptidoglycan structures meet. Here, critical activity happens.

First, enzymes within the forespore (denoted by ‘1’ in the figure) make a new bond with the cell wall ahead of the leading edge. With a new bond between the two, the old bond is no longer needed. Thus, enzymes in the mother cell break this old bond (denoted by ‘2’ in the figure).

Like this, the mother cell can slowly move around the spore until it completed warps around it.

Wrapping the spore in a thick coat

Once the mother cell engulfed the forespore completely, the spore needs to mature. For this, the mother cell builds thick and protective layers around the spore to protect it from the environment.

Ultimately, the mother cell lyses and dies and releases the mature spore into the environment. Only when the environmental conditions become favourable again, spores germinate and normal vegetative growth cycle starts again. 

Bacterial sporulation – a tightly regulated process

Although the process of sporulation sounds pretty simple, it can be extremely challenging to comprehend from the point of view of the bacterial cellular machinery. More than 500 genes are active only during sporulation. And these are not active during vegetative growth.

Also, some genes are only active in the mother cell and others only active in the forespore. And each stage of spore formation needs to be tightly regulated!

The studies of spore formation in Bacillus subtilis have undoubtedly increased our appreciation of what else bacteria are capable of.

However, there are still many unanswered questions and unknown genes during sporulation that we need to study.

Also, we need to expand these studies to understand sporulation in pathogenic spore-formers like Clostridium difficile and Bacillus anthracis so that we can develop treatments for these disease-causing organisms!

Recent sequencing analysis of the human gut microbiota also indicate that around 50-60% of bacteria in a healthy host intestine are spore-formers. But we still don’t understand the functional and physiological relevance of the majority of them.

There is definitely lots to explore and understand about this one-of-a-kind process of sporulation in bacteria!

The post Sporulation in Bacillus subtilis: A strategy for bacterial hibernation appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

What does stress mean for bacteria?

For humans, stress can come from juggling work, family, exercise, entertainment, and whatever else life throws at us (like a world-wide pandemic!). Bacteria also can get stressed; however, they experience and react to stress differently than us. Salmonella enterica is a great example of a bacterium that has many ways to deal with different stress in its life.

You’ve probably heard of Salmonella enterica because it can cause food poisoning. While there are many different strains of this bacterium, I’ll only be discussing the ones that lead to food poisoning and I’ll refer to it as Salmonella in this post. Unfortunately, there are about 1.3 million food poisoning infections a year from Salmonella.

About the pathogen Salmonella

Salmonella naturally lives in the guts of chickens, so handling chickens or eating undercooked or raw eggs could put you at risk of getting sick. That’s why you’re not supposed to eat raw cookie dough (even though it’s so good). Good hand hygiene and cooking meat and foods thoroughly reduce the risk of getting sick.

However, if by any chance a Salmonella bacterium makes its way into our bodies, it travels to the small intestine. Here, it will start to reproduce, leading to diarrhea and stomach cramps associated with food poisoning.

But if you think about it, it has to be challenging for Salmonella to live in all those different environments, from chicken guts to the inside of eggs to human stomachs and intestines. Each of these environments has a different temperature, pH, and different nutrients. And the change of just one of these conditions is “stress” for the bacterium. That’s where having the ability to deal with stress comes in handy for Salmonella.

Let’s look at each of these challenges for Salmonella bacteria and how they deal with stress.

How Salmonella handles temperature stress

Salmonella likes to grow in the warm environments of chicken and human guts.

And like humans, bacteria also react to being too cold. This can happen when Salmonella lives in a chicken egg and a chicken lays this egg. All of a sudden, Salmonella lives in outside temperatures. But instead of bundling up with some hot cocoa and a blanket, Salmonella makes proteins to protect itself.

When bacteria are too cold, the genetic information (DNA, RNA) stiffens and adopts a shape that’s hard for the cell to use. This is why the cell makes special proteins that protect the shape of DNA at colder temperatures.

Thus, the cell ‘blankets’ its genetic information to protect it and use it properly.

How Salmonella copes with acid stress

After coping with changing temperatures, Salmonella continues its journey to the human intestine. We consume Salmonella bacteria through contaminated food (like that raw cookie dough). Then they make their way down to the human stomach.

But our stomachs are very acidic. This is to help us break down food and kill pathogens. In acidic environments, proteins start to misfold and get destroyed, making them useless to the cell.

However, Salmonella and other pathogens know how to cope with this acidic attack. They produce so-called chaperones. These are special proteins that protect other proteins from misfolding. This keeps all other proteins active and thus the cell alive.

How Salmonella saves energy when food is limited

Now that Salmonella has survived the highly acidic stomach, it enters the intestines where it can find food and grow. Lots of bacteria live in our guts and all compete for the same amount of food.

For cells to grow, they need energy that comes from food. When food sources are limited, Salmonella cells will conserve energy by ‘turning off’ proteins that consume energy.

But why not just get rid of that protein if the cell does not need it anymore? The problem is, making proteins takes energy. If the cell needs the protein it just trashed in the future, the cell must invest more energy into making that protein again. By turning the protein off, the protein is not destroyed and can be used again later when conditions are better.

It is similar to changing from a green light to a red light at a traffic light. The red light halts cars from moving at specific times but does not destroy the car. Once traffic conditions favor that direction, the traffic light turns green and the cars can respond quickly and move through the intersection.

Similarly, Salmonella turns off its proteins in such a way that it can later remove the modification and restore the activity of the protein. Like this, Salmonella can respond quickly and turn on the protein when food becomes available. Once more food becomes available, Salmonella settles into the gut by eating, growing, and reproducing.

Unfortunately, as Salmonella gets comfortable in its new home, we become uncomfortable with fever, stomach aches, and diarrhoea. Now that sounds stressful!

Salmonella knows how to deal with stress

All these mechanisms of stress management allow Salmonella to thrive in a wide variety of environments. From chickens to humans, the road to pathogenesis is wrought with stressful situations. And lucky for Salmonella, it knows just how to deal with each of these situations of stress.

The ability to respond to stressful situations is common to bacteria, and each bacterium possesses its own set of proteins and pathways to handle stress and even aid in bacterial virulence.

So just like us, bacteria have to handle a lot of stress in their lives. But the more we learn about how pathogens like Salmonella deal with stress, the better we can fight them!

Take away messages from this week’s article

• Bacteria encounter many stresses in the environment
• They have various pathways to respond to different types of stress
• The ability to deal with varied environments and stress allows pathogens like Salmonella greater virulence and resilience

The post How does Salmonella deal with stress – a bacterial journey through the human body appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

Phages are basically genomic information – DNA or RNA – within a lipid-protein shell. Distributing their DNA or RNA into as many hosts as possible allows the phages to survive. They then reprogram the host to produce more phages packed with more phage DNA or RNA.

These newly produced phages then trigger the host to release themselves which can even kill the bacterium. With the release, the phages are spread further into the surrounding until they encounter another host and the cycle begins again.

Of phages and bacteria

Many different bacteriophages exist that specifically infect certain bacteria. So, just as their hosts differ, the phages differ as well. They come in different shapes, sizes and reproductive mechanisms.

Some phages have very simple shapes as in the picture below. Here, we will focus on the filamentous phages that can be even longer than the host bacterium itself.

Filamentous phages are very common in bacteria and they also have a special ability: They program the bacteria in a way that bacteria do not always produce the phage. They control the bacterium and wait until the right moment comes for them to be produced.

This means that these bacteria have DNA of the phages inside their own DNA. And only when the phage DNA is activated, the bacteria actually produce the phages. Until then, the phage is a so-called silent phage within the bacterium.

Let me be your phage

One bacterium that is infected with a silent phage is the pathogenic bacterium Pseudomonas aeruginosa. Within its genome, Pseudomonas aeruginosa contains the DNA for the filamentous Pf4 phage. However, it only produces this phage when the bacteria live in a biofilm community.

So, it seemed that the phages must somehow help the bacteria in the biofilm. As a new study found these phages actually help the bacterium become more resistant to antibiotics and chemical and toxic substances inside the biofilm.

But the way the phages achieve that is a fantastic antibiotic resistance mechanism that was not known before. To learn about the strategy, researchers took images with the microscope of the Pf4 filamentous phage. And they found these long phage filaments.

I wrap around you

While these structures were pretty impressive, they didn’t explain how the phages would actually behave within the biofilm together with Pseudomonas aeruginosa.

So, the researchers added some artificial biofilm from the bacterium to the phages. They then looked at the phages again in the microscope and they saw that the phage assembled and formed ordered filaments. These looked like highly organised nets of phages.

I protect you

The researchers then wanted to see how the bacteria could fit into these nets. So, they took images of the phages together with the bacteria. And they saw that the phages form their nets close to the bacterial cells just as in the picture below.

It seemed that the phage nets wrapped closely around the bacterial cells. Like this, the phages would form a droplet shape around the bacterial cell and separate it from the surrounding.

And these droplets are the foundation for the resistance to antibiotics of the bacteria. When researchers added different antibiotics to the phage-bacteria-droplets, the bacteria survived.

On the contrary, the bacteria on their own were dying from the antibiotic attack.

This means, that the phage net works as a wall to protect the encapsulated bacterium from toxic molecules in the surrounding. This is a completely new and remarkable mechanism of bacteria to protect themselves from environmental dangers. And they use their very own phages to do that!

It seems that another race against antimicrobial resistance just started…

And then I start again

Let’s put it all together and have a look at the life cycle of these phages:

Pseudomonas aeruginosa carries genes for the Pf4 phage in its genome and only activates them when it grows within a biofilm. At this moment, Pseudomonas produces both biofilm material and the Pf4 phage. These released phages then form nets around the bacterial cells. With this net, the phages protect bacteria from antibiotics and other toxic substances.

So, it seems that phages protect their own hosts from environmental dangers. After having hijacked the bacteria’s cell for their own production, it’s actually a pretty nice thing to do.

The post Love thy host: Phages protect bacteria from antibiotics appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

Yes, bubbles!

No, bacteria don’t just produce bubbles and try to hit another microbe with them. They are more sneaky. Bacteria fill these bubbles with antibiotics. And antibiotics are toxic and kill microbes.

So, when these toxic bubbles hit other bacteria, they will suffer.

Let’s look at where these bubbles come from and why bacteria decide to fill them with antibiotics.

Bacteria and their membrane(s)

Bacteria come in one of two kinds. They can have one or two cell membranes.

If a bacterium has one cell membrane, it is called Gram-positive. If it has two cell membranes, an inner and an outer membrane, it belongs to the Gram-negative bacteria. 

The outer and inner membranes of Gram-negative bacteria are slightly different. Interestingly, the inner membrane of Gram-negative bacteria is the same as the cell membrane of Gram-positive bacteria. But in Gram-positive bacteria, that membrane has a lot of additional stuff to make it thicker.

Because Gram-negative bacteria have two membranes, their outer membranes can form “blebs”. These blebs, also called vesicles, eventually form round spheres – or bubbles – and detach from the membrane which is how they are released into the environment.

Bacteria and their outer membrane bubbles

As you can see, these bubbles are made from the outer membrane of Gram-negative bacteria. This is why they are called outer membrane vesicles. These are basically a double layer of lipids in the form of a sphere with stuff inside. 

Within these bubbles, bacteria pack anything that they want to get rid of. This can be cell junk and can come from cell machines that don’t work anymore. Bacteria can get rid of that stuff by throwing it out.

About Chromobacterium violaceum

One bacterium that produces these outer membrane vesicles is Chromobacterium violaceum. And this one has a special reason to produce bubbles: it uses them to kill other bacteria.

Chromobacterium violaceum produces the antibiotic violacein. Violacein is a purple molecule and turns Chromobacterium colonies into purple dots. 

Since violacein is an antibiotic, it kills other bacteria. However, this antibiotic only kills Gram-positive bacteria, those with only one cell membrane.

The problem with violacein is, that it is a very hydrophobic molecule. This means that it is insoluble in water. Hence, researchers were interested to find out how Chromobacterium transports violacein through water to other bacteria. 

Chromobacterium violaceum bacteria produce toxic bubbles

So, researchers had a look at Chromobacterium cells. They saw that these bacteria produce bubbles from their outer membrane. And they do indeed look like spikey bubbles as in the picture below.

The researchers then purified the vesicles and added them to Staphylococcus aureus, a Gram-positive bacterium. The vesicles killed Staphylococcus aureus, hence the researchers thought that the violacein would be inside these vesicles.

Then they grew a Chromobacterium mutant that did not produce any violacein. But this mutant still produced outer membrane vesicles. Surprisingly, the vesicles from this mutant did not kill Staphylococcus aureus. 

From this, the researchers concluded that Chromobacterium transports the violacein within the bubbles.

This meant that the researchers found new functions for outer membrane vesicles. Hence, bacteria use them

a) to solubilise a hydrophobic molecule

b) to transport a hydrophobic and toxic molecule towards other bacteria

c) as bacterial weapons

Now, this concept gives researchers interesting possibilities to apply outer membrane vesicles.

Maybe, one day we will find a way to fill these bubbles with therapeutic molecules and send them towards tumour cells or we just found a new way to deliver antimicrobial substances in general.

For sure, scientists will come up with some cool new ideas to use outer membrane vesicles in the clinic, but as always, that requires a lot more research ?

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Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world