Those bacteria that call your gut their home are the so-called commensal bacteria. Luckily, they have a special superpower: They can protect us from bacteria that cause infections and make us sick. For this, our commensal gut bacteria developed some extraordinary strategies to defend these pathogens.

So, by nurturing our friendly gut bacteria, you are also strengthening your protection against diseases. Here, we will look at what kind of bacterial wars are going on in your gut and how your gut bacteria defend pathogens and keep you healthy.

Your gut bacteria defend pathogens with toxic molecules

Bacteria have many different means to kill other microbes, competitors or even their own siblings. Often, these bacteria produce molecules that are toxic to their prey, which means they inhibit cellular proteins or machineries. Without these machineries, the prey is then lacking an essential cell function to grow or survive, so that it eventually dies.

Interestingly, gut bacteria produce and deliver many different toxic molecules of various shapes and sizes, functions and even origins.

Gut bacteria produce bacteriocins

Many bacteria produce molecules that are like antibiotics specifically to kill bacteria. These are called bacteriocins.

Some bacteriocins are simple and small molecules, while others can be big and fancy. However, they all have a similar goal: they bind to a specific target in the prey bacterium and prevent that target from working properly.

So, no wonder that many bacteria in our gut microbiome produce bacteriocins that are toxic to pathogenic intruders. Also, we carry a lot of different bacteria in our guts and they all produce different bacteriocins. Hence, incoming pathogens face this huge load of toxic molecules making it really difficult to establish themselves in our intestines.

For example, one bacterium that loves the warmth and lack of oxygen in our gut is the bacterium Ruminococcus gnavus. And this one produces at least two bacteriocins, Ruminococcin A and C, that are toxic against human gut pathogens like Clostridium perfringens.

Other friendly gut bacteria, like Escherichia coli or Blautia producta, also produce bacteriocins that are toxic to pathogens, like Enterococcus faecalis. And some of their bacteriocins can even impact our gut cells by activating and strengthening our immune response.

Gut bacteria produce short chain fatty acids from fibres

Another way to protect against pathogenic gut bacteria is directly related to your diet. When we eat a lot of fibres, which are non-digestible carbohydrates, our friendly gut bacteria break these up. From these fibres, they produce small molecules that are called short-chain fatty acids, which have many positive health benefits for our overall wellbeing.

Interestingly, when we have a lot of these short-chain fatty acids in our intestine, the pH drops. This is already pretty difficult for most pathogenic bacteria, as not many can handle this acidic environment.

Plus, short-chain fatty acids diffuse into pathogenic gut bacteria where the pH drops as well. This can disturb many cellular machineries from functioning properly and not many bacteria have the right tools to defend against this attack, so they’ll die.

Gut bacteria convert bile acids into toxic compounds

To better digest the fats in food, our liver produces bile acids. These molecules bind fatty acids and lipids so that we can take them up better into our bodies.

But some of our friendly gut bacteria can convert these primary bile acids from our liver. For example, one of these bacteria, Clostridium scindens, transforms them into secondary bile acids that can bind the lipids of bacterial membranes.

Like this, secondary bile acids open the membranes of some pathogenic gut bacteria, like Staphylococcus aureus, Bacteroides thetaiotaomicron or Clostridoides difficile. This eventually kills the intruders and keeps our guts pathogen-free.

Killing pathogens with bow and arrow

Yes, also direct bacterial wars are happening in our guts! And they are nasty!

Some bacteria use tiny little bows to shoot deadly arrows into other bacteria. And these arrows can be incredibly toxic so the shot bacterium has barely any chance to survive the attack.

Luckily, our gut bacteria use their bows and arrows to defend against gut pathogens. For example, commensal bacterium Bacteroides fragilis has three different bows and can shoot various arrows. And research showed that this bacterial friend can protect us from bacteria that otherwise cause intestinal diseases.

Interestingly, Bacteroides fragilis is not opposed to hit’n’kill its own toxic bacterial siblings since some members of his family can indeed make us sick. But our friendly Bacteroides fragilis collected many different immunity proteins against its evil siblings so that their toxic arrows cannot harm it. Instead, Bacteroides fragilis keeps shooting and killing until we are safe from the pathogenic sibling.

Keeping nutrients from pathogenic gut bacteria

Another important way how gut bacteria defend pathogens is by keeping nutrients away from them. In all mixed microbial communities, bacteria fight for nutrients, especially for metals like iron, zinc but also sulphur sources.

Luckily, our gut bacteria developed some sneaky ways to steal these metals from gut pathogenic bacteria. By sending out special proteins that bind these metals very tightly, the commensals make sure to keep these metals from the pathogens. And if the pathogenic bacteria don’t have enough of these essential metals, they won’t survive and will eventually die.

Strengthening the mucus layer to block pathogenic gut bacteria

When you think about it, your gut is not part of your body – even though it is inside of you. All the food that we eat, stays within this digestion tube (mouth, oesophagus, stomach, intestines) until it comes out on the other side.

And to protect us from harmful microbes and molecules, we need to have a clear physical barrier from the content of the tube. This barrier is the so-called epithelial layer, which is covered by a slimy mucus on the outside. And this sticky slime helps keep off intruding microbes so that they cannot breach through the epithelial wall and get into our bodies.

Luckily, our helpful gut bacteria help us maintain this slimy defence wall. As bacteria produce SCFAs close to the mucus layer, the epithelial wall produces more slime. And if the slime gets thicker, gut pathogenic bacteria have more difficulties getting into our bodies.

To help the slime grow, some bacteria adapted very well to the conditions within the gut. For example, the friendly gut bacteria Akkermansia muciniphila and Ruminococcus gnavus cut off the very end of the mucus layer and feed themselves with them. This does not harm the mucus itself, but it keeps these bacteria close by. And this in turn triggers the epithelial wall to produce more mucus. So, everyone wins.

How to help your gut bacteria defend pathogens

Now, that you better understand how your gut microbiome defends pathogenic gut bacteria, make sure you support them keeping you healthy. By feeding your gut bacteria the right foods, you will help them be comfortable and happy in your gut. And when the right bacteria grow within you, they will gratefully protect you from nasty intruders!

Another idea for researchers is to use what they have learned to keep you healthy. The idea is to develop probiotics or prebiotics that help us defend against nasty pathogens. For example, you might take pills containing toxins against pathogenic gut bacteria or probiotics with bacteria that can fight off pathogens.

Whatever it may be, you can always help your gut bacteria be happy in your intestines by eating the right things. That means lots of fibre and veggies! ?

The post How bacteria in your gut microbiome defend pathogens appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

So, they talked of cocci and bacilli based on the spheres and rods that they saw under the microscope.

And they classified microbes and bacteria based on these shapes.

It came only with later, modern technologies that scientists learned that there was more to bacteria than their shapes. Even though bacteria looked similar, they had different superpowers.

Yet, some of these bacterial superpowers are indeed influenced by their cell shapes.

So, what is it about bacterial shapes? Why do bacteria look differently? And how do the different shapes of bacteria help them survive and thrive?

What gives bacteria their shapes?

To protect themselves from the environment, bacteria as well as all other organisms have cell envelopes. These keep the cellular machines and internal parts together so that a bacterium can function within this envelope.

And this envelope also gives bacteria their shape.

Both Gram-positive and Gram-negative bacteria have a layer of so-called peptidoglycan within their envelope. This peptidoglycan layer is made of sugars that are linked together by very strong bonds. This is why the peptidoglycan layer is pretty rigid and stiff and has a specific shape in each bacterium.

Either on the inside or on the outside, the peptidoglycan layer is linked to the cellular membranes. Together, these make up the bacterial envelope with a specific cell shape.

What different shapes do bacteria have?

Microbiologists have different ways to classify known bacterial shapes. Here, I will introduce you to the bacterial shapes according to what makes the most sense to me.

Rod-shaped bacteria

As the name suggests, these bacteria have a rod or cylindrical shape. Examples of rod-shaped bacteria are Escherichia coli and Bacillus subtilis.

Scientists are also convinced that rod-shaped bacteria are the evolutionary ancestors of all other bacterial shapes.

The shape comes from proteins that form long cables within the bacterial cell. These span out the whole bacterium from one end to the other.

Rod-shaped bacteria grow by two modes that we talk about in Why bacteria divide into two and grow with the help of a strong ring: First, they extend their cell size by growing the peptidoglycan, the cable proteins and the membrane.

Second, the cable proteins determine the middle of the cell, where the bacterium produces a special ring. Eventually, this ring narrows so that the bacterium divides and two bacterial cells form.

Spherical bacteria

The spherical bacteria – or so-called cocci – include many pathogenic bacteria like Staphylococcus aureus, Streptococcus pneumoniae and Neisseria gonorrhoeae.

Microbiologists think that spherical bacteria were once rod-shaped as well. However, spherical bacteria do not have these long cable proteins that extend their cell bodies. Thus, they stay spherical and grow by dividing their spherical cells right in the middle.

However, sometimes the two daughter cells do not completely divide and they stay attached to each other. This is why some spherical bacteria live as so-called diplococci.

Curved bacteria

Curved bacteria have the shape of a comma or banana and are sometimes also slightly twisted. Examples of curved or banana-shaped bacteria are Caulobacter crescentus and Vibrio cholerae.

These curved bacteria usually live in watery environments where there are flows. Here, the curved shape helps the bacteria to align with the flow while staying attached to a surface.

In the case of Caulobacter crescentus, one end of the bacterium is glued to a surface with a strong super glue. When this bacterium divides in the middle, one daughter cell remains attached to the surface, while the other one can swim away and find a new location to settle down.

Spiral bacteria

Spiral bacteria are a mix of rods and curves which give them a helical twist. Hence, these bacteria have a corkscrew shape.

Many pathogenic bacteria use their corkscrew shape to swim through gel-like solutions. This includes Helicobacter pylori and Campylobacter jejuni.

Since spiral – or helical – bacteria are also thinner, they can reach locations that are too narrow for other bacteria to reach. They also use their flagella to push themselves forward and “wriggle” through narrow pores.

Star-shaped bacteria

Some bacteria look even fancier than others: They are real stars – yes, bacteria with a star shape.

While we don’t know much yet about star-shaped bacteria, they belong to the so-called Stella species or are Methylomirabilis oxyfera. These usually grow in freshwater, soil and sewage.

The star shape comes from six little arms that extend out of the bacterial cell. These push and grow to the outside giving these bacteria a shiny star shape.

Why do bacteria have different shapes?

Now that we have seen the different shapes of bacteria, you might ask yourself, why do bacteria have these different shapes? How do they help them?

As always in biology, it comes down to how a property helps a bacterium survive in a certain location. Often, the cell shape gives a bacterium advantages over other bacteria and it is easier for them to settle down and face harsh environments.

For example, spherical cells have the lowest surface-to-volume ratio. This means they have a large envelope surface through which they can take up a lot of nutrients. All this while their cell volume is relatively small. So they don’t actually need that many nutrients. This helps cocci to grow in locations where there are little amounts of nutrients.

On the other hand, rod-shaped bacteria often have flagella. And thanks to their shapes, they are efficient swimmers. This allows them to swim to new places in cases of danger or the lack of nutrients.

Bacterial cell shapes help face harsh environments

Also, straight rod cells can pack into biofilms more efficiently and build organised structures. This helps them colonise different locations and resist dangerous environments.

Many rod-shaped bacteria also form longer filamentous organisms. These stronger and larger structures protect bacteria from being eaten by other organisms. Another advantage of these multicellular organisms is that they allow more cells to attach to surfaces and colonise hosts.

Lastly, both curved and helical bacteria use their shapes to get better around their environments. Curved bacteria grow in watery environments but also in our guts. Here, their shapes help them align with the flow of water or our gut content while they stay attached to a surface or the gut wall. This keeps them at their preferred location and protects them from being flushed away.

Spiral bacteria use a fascinating helical movement to screw through gel-like or viscous fluids. This for example helps pathogens swim through the mucus of our stomach and guts and colonise us and make us sick.

Bacteria and their shapes

Here, we looked at the different shapes that bacteria have and how these help them survive. Bacteria always face harsh and new environments and conditions and only survive if they have the right tools or means.

So, by adapting their shapes, bacteria often have advantages over other bacteria. Plus, they look cool and fabulous!

The post Looking fabulous: Why bacteria need to stay in shape too appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

Even though about 70% of the Earth’s surface is covered by water, a majority of that water we cannot drink.

The water that is available to drink can also be contaminated with toxic chemicals or certain microorganisms that would sicken us.

But not all microbes are bad. In fact, many microbes are helping us save our planet. One way of doing this is by cleaning up our drinking water.

We don’t have enough clean freshwater

Everyone needs water to drink.

Humans can only drink freshwater, which makes up less than 3% of the world’s water supply. Freshwater is found in lakes, rivers, and streams. It is also locked away in the icecaps as glaciers, up in the atmosphere as water vapor, and deep in the soil as groundwater.

Of the small amount of freshwater easily accessible to us, we have used or contaminated much of that freshwater. Agricultural practices have diverted many sources of freshwater for animals and crops. Climate change and warmer temperatures cause farmers to use more freshwater resources as well. And global industrial practices can lead to toxic chemicals entering the environment and water.

This means that now we have less freshwater available to drink than ever.

We have learned ways to clean our drinking water, but this requires a lot of chemicals, energy, and money. Good thing microbes can help us decontaminate our drinking water in faster, easier, and cheaper ways.

Microbes clean water by filtering out bad bacteria

Drinking certain types of bacteria can make us sick. You have probably heard of outbreaks of E. coli or Salmonella leading to people being ill.

These microbes normally live in animals’ digestive tracks and are excreted in their wastes. They can enter the water system from runoff from farms, and ingesting them can make us really unwell. Luckily, microbes can help remove pathogenic bacteria from our water.

A simple method of water filtration includes having water flow over a bed of microbes and sand to remove any contaminates, called ‘slow sand filtration.’ At the top of the sand is a gelatinous layer of microbes, known as a biofilm. In such a biofilm live various bacteria, fungi, protozoa, archaea, and other aquatic microorganisms.

This layer is the so-called Schmutzdecke, which is German for “dirty layer.” As water flows over this biofilm, microbes in the Schmutzdecke trap and consume particles and pathogenic microbes. Every Schmutzdecke layer has a unique community of microbes based on the contaminants in the water. In this way, beneficial microbes remove harmful ones and decontaminate our drinking water.

Slow sand filters can purify away 90-99% of contaminating bacteria! The Schmutzdecke removes most of the fecal contaminating bacteria like E. coli. This system does not involve the use of chemical disinfectants, which can select possibly pathogenic bacteria that become resistant to decontamination efforts.

Also, the Schmutzdecke feeds on the microbes and organic matter found in the contaminated water. Hence, slow sand filters are a cheap and low-maintenance way to filter water in resource-limited areas throughout the world.

Microbes clean our drinking water by preventing bacterial build-up

The Schmutzdecke is an example of a community of microbes filtering water to remove pathogenic microbes and make the water safe to drink. But decontaminating water does not always need a whole community of microbes. Sometimes just one part of a microbe is enough to clean the water. In fact, researchers have found a protein from bacteria that can help stop bacterial contamination.

Pathogenic bacteria like Pseudomonas aeruginosa can contaminate water lines that carry water to homes and businesses. To let other P. aeruginosa know they have found a place to stay, bacterial cells send messages to each other in the form of chemical molecules. This communication system, called quorum sensing, allows bacteria to ‘sense’ the number of other bacteria, (a ‘quorum’) around them.

If enough P. aeruginosa cells grow in the same area and send the same message, they will start to form a biofilm. Just like the Schmutzdecke, biofilms act as a gelatinous layer and are difficult to break up. That’s where that special bacterial protein comes in to help stop biofilm formation.

This protein is called AiiA_DH82 and comes from the deep-sea bacterium Bacillus velezensis (DH82 strain). AiiADH82 binds and degrades the chemical messages that bacteria use to communicate with each other.

Without those chemical signals, bacteria do not know they should start forming a biofilm. Adding AiiA_DH82 to P. aeruginosa cultures decreased bacterial growth and significantly inhibited biofilm formation in P. aeruginosa-contaminated water. Scientists hope one day to apply the AiiA_DH82 protein to water lines and drinking fountains. In these, bacteria could group to reduce bacterial contamination and keep our drinking water safe.

Microbes clean our drinking water

People everywhere need clean water for cooking, cleaning, and drinking. However, clean drinking water is a limited resource. Toxic chemicals or pathogenic microbes can pollute our water. Current methods to purify water cost a lot of energy and money.

We are fortunate that microbes are here to help us clean up our water and our environment. As the global population increases, using microbes to clean drinking water is a cheaper, sustainable and more environmentally friendly way to produce the needed levels of clean water. A great example of how microbes are making our world better.

Along with microbes, we can save the planet!

Take away messages from this week’s article:

• Clean drinking water is a limited and necessary resource for everyone on the planet
• Microbes can clean polluted drinking water by reducing the growth of pathogenic bacteria
• Microbial decontamination of drinking water is a sustainable and inexpensive way to provide clean drinking water to our increasing global population

The post How Microbes Clean our Drinking Water appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

They have killer weapons to deliver lethal toxins into other microbes.

And by killing their surrounding competitors, they make space for themselves.

Like this, they conquer new places and environments wherever they go.

But some bacteria are even more sneaky than that. They don’t kill bacteria directly. Rather, they destroy the houses that bacteria live in.

This leaves the prey exposed to the harsh environment. And the attacker can claim the now available space.

Where do these kinds of battles happen? According to researchers, they might even happen in or on our bodies.

Let’s have a look at how bacteria fight by destroying each other’s houses.

Bacteria build biofilm houses

Just like us, when bacteria feel comfortable in a place, they start building houses to settle down. They grow within these houses, multiply, invite their neighbours and become social.

A happy life.

One bacterium that is a master in biofilm house building is the Escherichia coli UPEC. This pathogenic bacterium can grow in the urinary tracts of people and cause nasty bladder infections.

In bladders or on catheters, UPEC can also build biofilms. Here, it wraps itself into a thick layer of slime to protect itself from the surrounding. In this biofilm house, no molecules, like antibiotics, or other bacteria can harm UPEC.

It seems to be protected from almost any attack.

Almost.

Bacteria fight microscopic battles

Now, researchers found that even UPEC has bacterial competitors. These live in similar places like UPEC, so they already know each other.

That’s why UPEC’s opponents came up with a special strategy to make UPEC miserable. They learned to destroy UPEC’s biofilm houses. This is meant to weaken UPEC so that other antibacterial factors now have an effect.

What does that mean?

The UPEC bacterium is pretty nasty for us since we need high doses of antibiotics to get rid of it. And we know that taking antibiotics is not a good thing. So, researchers are looking for new weapons to fight this bacterium.

The idea is that if we understand how other bacteria fight UPEC, we could learn from them. Maybe we could work out similar ways to fight UPEC.

Bacteria fight by destroying biofilms

Researchers found that some bacteria produce compounds that stop UPEC from producing biofilm. One of these attackers is Salmonella enterica Typhimurium. This bacterium even developed a strategy to exclude UPEC from its own biofilm house.

Researchers showed that Salmonella produces a toxic sugar that inhibits UPEC from forming a biofilm. Like this, Salmonella directly stops UPEC from colonising new spaces.

Another bacterium, Lactobacillus acidophilus, produces a similar sugar. Researchers showed that this toxin also stops UPEC from building a biofilm.

However, it is still not clear how these sugars exactly work to inhibit biofilm production.

Bacteria fight by producing biofilm

The researchers also found that Salmonella and UPEC did not grow well together. Separated from each other, they were happy. Together, they were just fighting.

But something else was interesting: In a mixed biofilm, Salmonella managed to outgrow UPEC. It was growing faster and produced a lot more biofilm than UPEC.

This could mean that Salmonella tries to suffocate UPEC with biofilm. The researchers thought that the Salmonella bacteria grow on top of the biofilm, where they have more oxygen. Like this, the UPEC bacteria would be buried by all this biofilm slime and get less oxygen and eventually die.

Surely not a nice way to go!

What can we learn from these bacterial battles?

This study told us a lot about how bacteria live together and fight each other. Researchers are constantly looking for new ways to kill those bacteria that we cannot fight with antibiotics anymore. Based on this, we can even use bacteria as biocontrol agents to fight other pathogenic bacteria.

For example, Salmonella produces a compound that stops UPEC from forming biofilms. If we better understand how this toxin works, we might have a new method to inhibit bacteria from colonising surfaces in hospitals.

Also, UPEC and Salmonella are pathogenic bacteria and they can survive in wastewater even after cleaning. This is a major health issue. Hence, finding new ways to fight these bacteria will help us live healthier and safer.

This study was a small step in the grand fight against superbug bacteria. But those small steps are often the most important ones.

The post Bacteria fight by destroying each other’s biofilm houses appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

Vaccines helped eradicate deadly diseases like smallpox.

And for over a century, researchers developed vaccines according to Pasteur’s principle. They isolated the microorganism and inactivated it. Then they injected the now harmless microorganism into people. 

Now these people were vaccinated.

Their immune systems would detect this foreign microorganism and develop antibodies against it. The next time this person gets infected with the real microorganism, the antibodies would be ready to fight the intruder.

New challenges for researchers

But unfortunately, developing vaccines is not always that easy.

Especially, when researchers have trouble growing an organism in the lab. As it is the case with the hepatitis C virus. And then there are nasty pathogens like Neisseria meningitidis. These know too well how to hide from the immune system and cause deadly meningitis. Or to fight a clever virus like HIV, we need help from extra skilled parts of our immune system. Let alone a virus as SARS-CoV-2 that emerged from nowhere and for which we need a vaccine real quick.

To develop vaccines against these microorganisms, researchers needed a new strategy. They try to find new vaccines that activate the immune system and trigger it to produce antibodies. These antibodies have to detect a specific piece of foreign microorganism. Often, this is a protein from the surface of the virus or the bacterium: the so-called antigen. 

But not every antigen is a good antigen that activates the immune system.

Hence, researchers need to produce and test different antigens. And for this, they rely on fancy technologies and super-efficient helpers: bacteria. Here, we will look at how researchers use bacteria in the hunt for vaccines. 

Bacterial pets in the lab

For some researchers, the bacterium Escherichia coli is a dear lab pet. They know exactly how to grow, change, regulate, mutate, shock and kill this bacterium. And they appreciate that their favourite lab bacterium can carry big chunks of DNA and produce almost any protein.

So, to produce and test antigens, researchers need to make DNA with a gene for an antigen.

Bacterial machines to produce DNA

To produce any piece of DNA, researchers use a special DNA production machine from the bacterium Thermus aquaticus. This bacterium lives in hot regions, so its enzymes only work at hot temperatures. 

Hence, researchers can control this DNA production machine by regulating the temperature. And like this, they can produce any gene they need.

Bacterial machines to cut and paste DNA

The problem is that the gene alone is not stable. This is why researchers need to put this gene (in blue in the picture below) into a plasmid. Plasmids are stable DNA circles (in yellow), that bacteria recognise and produce. 

To link these two pieces of DNA together, researchers use special scissors. These scissors cut the gene and the plasmid so that they now work like puzzle pieces. They can only fit together. 

These scissors also come from bacteria and, interestingly, every bacterium has its own type of scissors. This means researchers can produce many different puzzle pieces that always work in pairs.

Next, the plasmid and the gene need to be glued together. And for this, researchers use a glue stick from a virus. And yes, it works like the plaster in the picture.

Finally, we have a big chunk of DNA with a gene for an antigen.

Now, researchers need to produce this antigen.

Guess what, they use bacteria for that too!

Bacteria are protein production machines

First, the plasmid with the gene for the antigen needs to go inside the bacterial cell. For that, researchers electrocute the bacteria together with the plasmid. Yes, electrocute them! Poor bacteria!

But this brings the plasmids into the bacteria.

Next, researchers grow these bacteria with the plasmid. The bacteria now produce a lot of that plasmid and a lot of that antigen (blue).

Next, researchers need to kill the bacteria and clean the antigens from them.

With all the antigens produced now, the fun experiments can get started. 

Finding the best antigen for a vaccine

Generally, researchers produce many different antigens to find the best one as a vaccine. The best antigen is the one that binds to an antibody the tightest.

To test all the antigens, researchers do an experiment that is funnily called ELISA. And they can do this ELISA experiment only thanks to bacteria.

Some bacteria from the Streptomyces family produce the protein streptavidin. This protein binds very, very tightly to the vitamin biotin. Obviously, researchers make use of these two proteins in the lab.

In the simplest version of an ELISA experiment, researchers glue antigens to a surface (yellow, blue and green). Then, they add liquids with different antibodies (grey) to these antigens to test which one binds most tightly. 

These antibodies are linked to a biotin molecule (grey circle). Next, the researchers add streptavidin (green) that is linked to an enzyme. Now, only if the antibody bound the antigen, the streptavidin can bind the biotin. And if that happens, the enzyme can change the colour of the liquid. 

Like this, researchers can test many different antigens and “see” for which the colour changes. These are the ones that bound to an antibody.

Researchers need to repeat all these steps many times; each time changing the antigen a bit to make it more efficient.

But eventually, this antigen becomes a vaccine.

And just as bacteria produced the antigen in the lab, they might have to do that in large amounts to produce the masses of vaccines needed.

About vaccines produced by bacteria

Bacteria can produce different proteins and therefore different vaccines.

For example, the vaccine against the hepatitis E virus is completely made by bacteria. Bacteria produce the envelope proteins of the virus. These then assemble and build the virus structure. This vaccine now has the same structure as the virus, but it is inactive and harmless since no viral DNA is inside the envelope. 

Some vaccines also have components from different organisms. 

Our immune system can very well detect the sugars on the surface of bacteria. Hence, researchers attach some of these sugars to vaccines. Like this, they attract the big players of the immune system to the vaccine. This activates the immune system so that it develops antibodies against the vaccine.

Researchers also linked bacterial proteins to vaccines. Here, researchers found that bacterial toxins or proteins from the bacterial surface attract and activate the immune system. But not to worry, researchers worked out how to inactivate the toxin so that the vaccine is not harmful.

Not all vaccines are produced by bacteria

Lastly, researchers developed new strategies to produce vaccines without bacteria. And they even use this strategy for some vaccine candidates against SARS-CoV-2 that causes the COVID-19 disease.

These vaccines only contain a piece of RNA enveloped in a lipid membrane. And, yes, this concept looks a lot like bacterial outer membrane vesicles that transport DNA or drugs. 

In this case, our body produces the protein – the antigen – from the RNA. This again activates the immune system and triggers it to make antibodies against the antigen.

So while the delivery mode of the vaccine is pretty different, the way to activate the immune system is still the same.

Bacteria are important in the hunt for vaccines

Some microorganisms are real burdens to the world population. Hence, researchers had to come up with new strategies to tackle them. There is no vaccine against the nasty SARS-CoV-2 yet, and maybe the final vaccine will be produced completely independent of bacteria. But still, bacteria are massively helping researchers in the lab. 

They are amazing little machines to produce proteins or transport DNA or drugs. And they evolved helpful enzymes that every lab researcher uses daily. No biology-related research would work without the amazing mechanisms of bacteria.

Ever since the pandemic started, a lot of people ask me whether we can have bacteria kill the nasty SARS-CoV-2. I doubt it will be a direct fight between bacteria and viruses. But I am convinced that in the end bacteria and their superpowers will save this planet.

Researching and writing this post was possible due to the Journalism Research Grant from the Berlin Science Week.

it’s been a great first adventure as a proper science journalist at the #BerlinScienceWeek https://t.co/ZlJFOb9e18

— Sarah Wettstadt (@DrBommel) November 6, 2020

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

Bacteria become resistant to antibiotics. 

Cancer spreads like never before. 

And a virus determines how we live our lives. 

Why do we need to transport drugs within our bodies?

These three major problems need researchers to develop new drugs, like new antibiotics, efficient chemotherapeutics, or long-lasting vaccines.

But we also need to transport these drugs into our bodies and to a specific location. This could be the site of a bacterial infection or the tumor that we’re trying to kill. 

For this, researchers have been working on new delivery methods to transport drugs to a specific site. And, interestingly, many of these methods are based on bacterial mechanisms. So, we felt it was more than worth discussing some of these mechanisms here with you. This will show you another way of how bacteria can save this planet by transporting drugs within our bodies.

Let’s dig in.

Outer membrane vesicles

In Bacteria firing toxic bubbles, we learned that Gram-negative bacteria can form bubbles of their outer membranes. These bubbles are called outer membrane vesicles and they can be filled with stuff.

And researchers also tried to use these bubbles to deliver drugs.

Luckily, our immune system can recognise and respond to outer membrane vesicles. This means our bodies can produce antibodies against the surface of these outer membrane vesicles. 

Outer membrane vesicles carrying stuff on their surface

For example, researchers made the bacterium Escherichia coli produce outer membrane vesicles. Only the lipids of the vesicles – nothing else. They then gave these outer membrane vesicles to mice. These outer membrane vesicles were not dangerous and the mice did not produce antibodies against them.

Then the researchers engineered the vesicles. Between the lipids, the vesicles now carried proteins from the pathogenic bacterium Acinetobacter baumanni. Hence, the protein becomes a so-called antigen. This means, that the mice produced antibodies against the antigen. This made them immune against an Acinetobacter baumanni infection. 

This is an option of how to transport antigens into our body to make us immune against different pathogens.

Outer membrane vesicle bubbles filled with stuff

Another way of using bubbles from bacteria to transport drugs is by filling them with stuff. 

For this, the outer membrane vesicle carries a specific protein. This protein fits like a key to a lock of a certain cell type. Like this, the outer membrane vesicle can dock onto a specific human cell and interact with it. 

Just as you can see in the picture above how outer membrane vesicles are formed, this mechanism can also work the other way around. An outer membrane vesicle can “melt” into a human cell. Then, the content of the outer membrane vesicle flows into the human cell. 

For example, researchers engineered outer membrane vesicles and filled them with a chemotherapeutic. This outer membrane vesicle then specifically melted with cancer cells and shed their content into these. This did not completely kill the tumour but inhibited its growth.

Researchers also developed new vaccines that have DNA or RNA inside these lipid membranes. Read more about vaccines made by bacteria.

As exciting as this mechanism sounds at the moment, it still requires more research to fully understand how we could use outer membrane vesicles as drug-delivering vehicles.

Magnetosomes – bubbles following a magnetic force

Magnetosomes are similar to outer membrane vesicles, as they are bubbles made of a lipid membrane. But in How bacteria read and follow the Earth’s magnetic field, we learned that magnetosomes also have iron-clusters that make them magnetic.

Researchers have the idea to guide magnetosomes with a magnet to a specific location in our bodies. Like this, magnetosomes can go deep into tumour tissue and work their magic there.

Now, similarly to outer membrane vesicles, magnetosomes can be filled with drugs like antibiotics or chemotherapeutics. These drugs are then shed into tumour cells or into the surrounding of tumour cells. 

So far, researchers showed this method in mice. They filled magnetosomes with a vaccine against a tumour, gave them to the mice and held a magnet right next to the tumour. This treatment protected the mice from the tumour and could be used at some point in the clinic. 

Bacterial ghosts – a shell of a dead bacterium

Ghosts of bacteria in your body? That is certainly a science fiction idea.

For this, researchers grow bacteria in the lab and engineer them to produce a protein of interest. This could be for example an antigen that will trigger an immune response in the human body. 

When the bacteria are fully grown, researchers trigger them to produce massive tunnels in their outer membrane. All the content of the bacterial cell will flow out into the surrounding. This means, the bacterium itself is dead and cannot grow anymore. But the bacterial envelope with the antigen is still stable. 

Studies showed that bacterial ghosts with antigens triggered antibody production in rabbits.

In another study, researchers filled the bacterial ghosts with anti-cancer drugs. Fortunately, the bacterial ghosts release the drugs very slowly. Like this, the drug is administered over a long time and is thus more efficient. However, researchers did these basic experiments only on cell lines so far. Hence, a lot more research is required to better understand this mechanism of drug delivery.

Living bacteria to transport drugs

Transporting drugs in the body using living bacteria sounds pretty challenging. But researchers know how to engineer strains that have no damaging effects on our bodies and our immune system. 

Using living bacteria to transport drugs in the body even has many advantages.

Bacteria are attracted by certain chemicals

Bacteria do chemotaxis which means they are attracted by certain chemicals or molecules. 

For example, some bacteria are attracted by areas with low or no oxygen at all. Cancer tissue generally lacks oxygen and the surrounding tissue has very low oxygen concentrations.

Hence, some bacteria are already directly attracted by tumours or cancer tissue.

Also, researchers are trying to engineer bacteria that are attracted to other chemicals. For example, they improve chemotaxis in some bacterial strains. And now these bacteria are more efficient in recognising certain molecules within tumour tissue.

Bacteria move with their flagella

After being attracted by a certain molecule, bacteria actively swim towards this molecule. For this, they use their flagella and pili. 

Hence, this swimming behaviour brings them efficiently to the site of infection.

Bacteria produce drugs on the spot

Bacteria are drug production machines. 

Generally, researchers engineer bacteria in a way that they start producing drugs only when they reach a specific location.

Like this, bacteria produce the right drug at the right time and the right location. 

And they can even produce multiple different drugs. How efficient!

Bacterial hybrid delivery systems – Microbots as the future?

Using a hybrid system between an engineered bacterium and a non-living unit sounds a lot like science fiction. These systems are even called microbots or bactobots. But also here, they have only been tested in the lab, and no studies on humans were done yet (at least to my knowledge!).

A microbot consists of a bacterium that does chemotaxis. So, they could be attracted to tumours or cancer tissue.

And this bacterium carries a nanoparticle that is filled with a drug. Like this, the bacterium steers the particle, and thus the drug, to the place of infection. Here, it can release the nanoparticle, which can now work its magic.

So far, researchers showed in a preliminary study in mice, that bacteria can successfully deliver nanoparticles covered with DNA into specific organs.

However, there are still so many obstacles to consider. But it certainly sounds like a promising and very efficient science-fiction idea.

Bacteria and their organelles can transport drugs within our bodies

Here, I showed you some ideas of how researchers are trying to use bacteria or their organelles to transport drugs within our bodies.

We looked at “bacterial organs” like outer membrane vesicles or magnetosomes. These could carry drugs and deliver them to certain body tissue.

We then discussed how researchers are trying to better understand bacterial ghosts to use them as drug vehicles.

And we explored living bacteria and why researchers think they can use them to transport drugs within our bodies.

Microbots, however, sound like science fiction so far. But, who knows, maybe at some point, we will eat a bacterium that carries a nanoparticle filled with drugs.

I hope we could yet again show you a fantastic way of how bacteria can save our medical problems and thus our planet. So, now is the time to lose the fear of bacteria and believe in them. 

Together with bacteria, we can save this planet.

The post Of microbots and bacterial ghosts – How bacteria could transport drugs within our bodies appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

But as we know all this plastic is seriously hurting our planet, the animals on it, the plants and also ourselves. Not only plastic is incredibly stable and its breakdown products can be found almost everywhere, but producing plastics takes a massive toll.

Producing plastics hurts our planet

Making plastic materials is an energy-rich process that requires extracting and burning fossil fuels and petroleum. Chemicals from petroleum are extracted and combined into long chains called polymers.

However, petroleum and fossil fuels are resources that are limited. Plus, burning fossil fuels releases a lot of carbon dioxide, which leads to climate change and air pollution.

Currently, it is still easier and cheaper to make new plastics than recycling and reusing the already plastic items. Plastics are very durable, so it takes a lot of energy to break them down and melt them into a reusable form.

The idea is to find a greener and more sustainable way to make plastics.

Gladly, there is—bacterial-generated plastics!

Bio-plastics from bacteria

Many bacteria produce products that we use in our daily lives, from fermented foods like yoghurt, kombucha and beer to biofertilizers and ethanol that we use for biofuels. For example, the bacterium Escherichia coli, commonly known as E. coli, produces many medicines, like antibiotics and insulin used for diabetic treatment.

So, asking bacteria to make plastic isn’t that hard to believe.

How do bacteria make bio-plastics? 

Plastics are long chains of smaller units called plastic monomers. These monomers can look different, which finally make the different kinds of plastics.

When bacteria have too much energy inside their cells, they produce a lot of these monomers. They then link these monomers into polymers to store energy.

Interestingly, different bacteria can produce different kinds of monomers. And different combinations of these monomers make different plastic polymers.

When living organisms like bacteria or fungi produce plastics, these plastics are called bio-plastics.

For example, several microorganisms, such as Burkholderia xenovorans and Pseudomonas strains produce the polymer polyhydroxyalkanoate (PHA). In these cases, PHA serves to store carbon and energy during times of hunger.

You can understand PHA as fat in our bodies; the bacteria store energy and carbon for when they need the extra energy. But instead of viewing PHAs as fat, researchers are learning ways to use these polymers to create sustainable, biodegradable bio-plastics!

Engineering bacteria to produce bio-plastics

By learning how to use building blocks already made in nature, we can create plastics that are a lot healthier for the planet. But first, scientists need to make sure bacteria can produce enough bioplastic polymers to meet the worldwide demand.

To achieve this, even bacteria need some engineering help from scientists to produce more of the bio-plastics. Maybe engineering bacteria sounds scary, but it just means adding genetic material to a bacterial cell so that the cell knows how to produce the wanted product.

Genetic engineering is how E. coli makes insulin. And that same E. coli can also be engineered to make bio-based polymers.

One group even engineered E. coli to produce common plastic building blocks from the simple sugar glucose. Glucose is an abundant and renewable starting material, making bacterially produced plastics more sustainable than processes that rely on fossil fuels. Plus, this one-step process using E. coli is much simpler than the current way to make plastics.

But it is not just E. coli that scientists are trying to use to make bio-plastics. Researchers engineered both the bacteria Novosphingobium aromaticivorans and Ralstonia eutropha to produce biopolymer building blocks. However, we still need more research to optimize the process.

Benefits of bacterial bio-plastics

The plastics made by bacteria require less burning of fossil fuels, while many precursors used by bacteria are also sustainable. Both reducing non-renewable resources and instead using renewable resources makes bio-plastics a healthier and ‘greener’ option for the planet.

Additionally, some of the bio-plastics are more biodegradable than conventional plastics. Because these polymers are already natural products, other microorganisms and natural processes already know how to break them down and release natural products back into the environment.

Synthetic polymers found in traditional plastics are meant to last forever and can take decades to break down! This means that all the plastic trash fills up our landfills and oceans.

One study found that a bio-plastic item had a lower environmental impact as compared to a traditional plastic item over the item’s lifetime. That’s because the production of bio-plastics emits fewer greenhouse gases, uses fewer fossil fuels, and produces fewer toxins as compared to traditional plastic production.

In all these ways, bacterial bio-plastics are making the Earth greener.

A greener future with bacterial bio-plastics

Plastic pollution is a threat to our planet. These items overflow our landfills and oceans, where they sicken us and wildlife. In 2010 alone, it was estimated that up to 12.7 million metric tons of plastic ended up in the oceans! All this plastic hurts aquatic life and our planet’s marine ecosystems.

Luckily, scientists and engineers are exploring ways for bacteria to reduce our plastic pollution, both by creating bioplastics and degrading already produced plastics.

Using bacteria and bacterial enzymes, we can soon produce biodegradable plastics with less energy. From food to medicine to plastics, microbes are important for producing items we need to live.

However, even with microbes’ help, we can all play a part by reducing our plastic consumption, buying reusable over disposable products and recycling our plastics appropriately.

Along with microbes, we can save the planet!

Takeaway messages from this week’s article

• Plastic production is a major burden on the planet
• Bacteria can produce the building blocks for bio-plastics
• Bio-plastics start with sustainable precursors and are more environmentally friendly as compared to fossil fuel-derived plastics

The post Bacteria produce green bio-plastics appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

We are completely surrounded by them and we surely would not be the same if it was not for our microbial friends.

Unfortunately, every once in a while, we read and hear negative news articles about certain players of the microbial world. And then we forget that many other microbes and bacteria are actually very helpful to us, our health, the environment and food production.

But the goal of the BacterialWorld blog is to remind you how colorful and interesting the microbial world is.

20 interesting microbes everyone should have heard about

The microbial world consists of many interesting players: bacteria, viruses, phages, fungi, protozoa, unicellular eukaryotes and microscopic animals. And together, they all make the microbial world such a diverse and fascinating environment.

So, here, we assembled a list of common and interesting microbes. Some of them you might find delightful, others you rather want to avoid and that is okay.

We want you to be aware that there are many more cool microbes and bacteria out there than what you hear in the news.

And that thanks so research, we know a lot about how to use these microbes or how to avoid them if they are dangerous.

For this list, I got help from microbe lover Rachel and her GIANTmicrobes which she introduced during the #MicrobesinMay challenge on Twitter.

Ready to learn about the microbial world and interesting bacteria and microbes?

1. The bacterium Escherichia coli

Escherichia coli is rod-shaped and can have flagella all around its cell. 

Most people have heard of Escherichia coli because of contaminated food or lakes. However, most strains are harmless and this bacterium is actually super important for your digestive health.

This is also why Escherichia coli is by far the most intensively studied and best-understood organism on the planet.

Escherichia coli serves as a model organism for microbiology and biotechnology. It is helping scientists to learn about everything DNA-related, as well as protein production and cell growth. In most research labs of biological or life sciences, scientists use this organism every day to produce proteins, produce gene fragments or use it as a vehicle for plasmids and vectors.

2. The Influenza virus

The influenza virus is an RNA orthomyxovirus that causes respiratory infections, which you may know as the ‘seasonal flu’. Luckily, there is a vaccine against the flu that you should get every year if you are able to.

Influenza is an RNA virus that contains 8 genetic segments. Generally, RNA viruses are prone to mutate a lot; this happens during so-called antigenic drift and antigenic shift events. These “shifts and drifts” can change the structure of the virus’s surface proteins. Unfortunately, this change makes it harder for our immune system to recognize and respond to the virus.

Because the flu virus is ever-changing, you should help your immune system to recognize the new antigens. You can do this best by getting the new FluShot every season. But be aware that each virus is different and a FluShot will not protect you against other viruses.

3. The fungus Saccharomyces cerevisiae

You may encounter this fungus – almost on a daily basis. Saccharomyces cerevisiae is also known as the common yeast.

We use this yeast to make beer and bread. Like many other microorganisms, Saccharomyces cerevisiae performs microbial fermentation. This means it eats sugar and turns it into alcohol in beer and CO2 for bubbles in beer and bread.

We cannot state enough that the yeast Saccharomyces cerevisiae is a fungus and not a bacterium. It produces rounded cells and researchers use it as a model organism for eukaryotes. This means its DNA is enclosed in a membrane and not swimming around freely as in bacteria. Humans are also eukaryotes, so lots of knowledge of human cellular and molecular biology comes from yeast research.

Saccharomyces cerevisiae also plays a role in biotechnology. Some strains produce biofuels while others produce recombinant proteins that we use as therapeutics.

4. The bacterium Lactobacillus acidophilus

Lactobacillus acidophilus gets its name because it produces lactic acids from sugars, which usually makes its surrounding very acidic.

Lactobacillus acidophilus cells are rod-shaped and usually grow in pairs or chains. This bacterium lives in our mouths and guts where it prevents the growth of other bacteria by maintaining a healthy microbiota.

This bacterium also helps make yogurt, since it breaks apart milk sugars to make acids and other healthy molecules. This is why Lactobacillus acidophilus is also a probiotic, meaning a microbe that promotes health. There are many claims out there promoting its use to increase health, but more research is needed.

5. The Rhinovirus

The Rhinovirus may look cute but it is one of those nasty viruses that you may not like. It causes the common cold and we all know how we feel not cute with a cold. There are more than 100 different varieties of rhinoviruses and together they cause almost half of all colds.

Rhinovirus is an RNA virus in a 20-sided capsid. They are some of the smallest viruses and can spread by aerosol or direct contact. The virus replicates best in temperatures slightly cooler than body temperature, like in the nose. In fact, “rhino” means nose in Greek.

Currently, there is no vaccine against Rhinovirus. And since it’s a virus, antibiotics won’t work against it.

The best way to protect yourself is good hand hygiene and physical distance from people with a cold.

6. The microscopic water bear

One of the most interesting and cutest microbes is definitely the water bear.

But what exactly are water bears?

Hypsibius dujardini are microscopic creatures, classified as the Tardigrada phylum.

As the name suggests water bears resemble bears and walk on eight tiny legs. Tardigrade means “slow walker”. So if you imagine a slow-walking bear through water, this is kind of what water bears are!

Besides being adorable, water bears can survive extreme conditions and they are found worldwide in diverse environments. Many species live in water or around moss. To survive in any habitat, water bears enter a state of cryptobiosis where it dries out and stops its metabolism. In this state, they can last several decades.

Water bears can live in hot springs, polar ice, mountains and deep in the ocean. In fact, researchers found that water bears can even survive the vacuum of space! That’s good since a capsule containing some crashed on the moon in 2019.

Learn more about what tardigrades look like under the microscope.

7. The microscopic rotifers

To us, Rotifers are certainly one of the most interesting and cutest microbes. These microscopic animals are almost all female and can reproduce without the involvement of males.

Rotifers are tiny free-living creatures found mostly in freshwater. Rotifers have a cylindrical body and a ring of cilia around their heads. When the cilia move, it appears as a wheel (rotifer means “wheel bearer”). This movement pushes food into the animal and helps them move through the water.

Rotifers are sexually dimorphic and the males are much smaller and usually do not live long.

Reproduction of this microbe is rather interesting: Unfertilized eggs grow as clones within their mother. But studies have found genetic differences without sexual reproduction. It is now just a question of how?

8. The bacterium Porphyromonas gingivalis

The bacterium Porphyromonas gingivalis causes bad breath and gum disease, so make sure to brush and floss regularly to keep it in check.

Porphyromonas gingivalis cells are rod-shaped and live in our mouths. They are anaerobic, so they don’t need oxygen to grow. This may seem odd since we should have oxygen in our mouths all the time. However, many different microbes grow in our mouths where they form biofilms. These are layers of almost no oxygen, in which the bacteria settle.

In the oral biofilm, the dental plaque, Porphyromonas gingivalis lives close to the gum line where oxygen is depleted. Here, the bacteria can infect the gum and cause erosion called periodontitis.

9. The Rubellavirus

The “little red” Rubellavirus is known to produce red rashes on children’s arms and faces. Luckily, there is a vaccine to prevent infection.

Rubella is an RNA virus in a 20-sided capsid wrapped by a lipid membrane. Also called German measles because it was first identified in Germany, rubella was once a common childhood disease causing rash, fever and sore throat. While it posed minor risks to children, rubella could be deadly for the unborn in the womb.

Today rubella is very rare because of the MMR vaccine, which protects against mumps, measles, and rubella. Thanks to scientific research and vaccination, many countries could be declared “free of endemic transmission of rubella”.

10. The morbillivirus

Separately, the virus that causes the measles. This virus leads to red spots all over the body and can be deadly. Fortunately, the MMR vaccine prevents infection.

Morbillivirus is a spherical RNA virus. Measles is very contagious and spreads by personal contact and contaminated surfaces. It infects the respiratory system and causes rash, fever, cough, running nose and red eyes. Measles can cause serious complications and be deadly for kids.

Today, morbillivirus is still responsible for more than 100 000 deaths yearly, down from more than 2 million deaths annually. This is due to the introduction and widespread use of the MMR vaccine.

11. The bacterium Shigella dysenteriae

If you’ve ever experienced Shigella dysenteriae, you would remember! This bacterium infects the intestines and causes shigellosis, which is incredibly painful and uncomfortable. Antibiotics treat this disease, but hygiene is the best prevention.

Shigella dysenteriae are rod-shaped bacteria. They have a biological needle with which they fire the so-called ‘Shiga toxin’ into our gut cells. This leads to stomach pain and watery diarrhea.

This bacterium travels through the fecal-oral route, from contaminated food or hands. It is very contagious because it needs only a few cells to make someone sick.

What’s the best way to protect yourself? Always cook food thoroughly to kill all bacteria. And wash your hands to prevent spread!

12. The human papillomavirus

This virus may look cute, but human papillomavirus has been linked to certain cancers! The human papillomavirus is a common virus that infects many. Thankfully, there is a new vaccine to prevent high-risk infections.

The human papillomavirus is a DNA virus surrounded by a circular capsid. This virus is very common and in most cases, one may not have any symptoms while the body clears the virus.

Sometimes, the virus causes small tumors called papillomas that appear as warts. If left untreated, those tumors can become cancerous.

The human papillomavirus spreads by direct contact and is one of the most common sexually transmitted diseases worldwide. A vaccine is available to prevent infection from the major cancer-associated human papillomavirus types.

13. The bacterium Anabaena

Anabaena, known as cyanobacteria, are photosynthetic bacteria, even though they resemble eukaryotic algae. These helpful bacteria contain pigments that give Anabaena the blue-green colour.

Commonly found in aquatic environments, cyanobacteria use their pigments to convert light into energy. Using that light along with CO2 and water, they convert it to sugar and oxygen. In fact, cyanobacteria are a major source of oxygen in our atmosphere today!

The bacteria are even more interesting since some of their cells have special superpowers. These so-called heterocysts can “fix” nitrogen.

Heterocysts have extra thick- cell walls to exclude oxygen that otherwise harms nitrogen-fixing enzymes. The heterocysts then share the fixed nitrogen with surrounding cells.

14. The bacterium Clostridium botulinum

Clostridium botulinum produces a neurotoxin known for causing botulism. But that same toxin is also a component of Botox. Just another way we use microbes for good.

Clostridium botulinum is a rod-shaped, spore-forming, anaerobic bacterium. Found in soils, it can enter the food supply as spores. Under correct conditions, like in canning, spores germinate and produce the toxin. Thus, food should be processed with high heat and pressure to kill spores.

The botulinum toxin is the most toxic substance known and causes paralysis. While botulism is serious and can be deadly, scientists found ways to use the muscle-paralyzing function of this toxin. In small doses, the toxin treats muscle disorders such as spasms. Also found in Botox, the toxin paralyzes muscles that lead to wrinkles.

15. The varicella-zoster virus

Remember those itchy spots caused by chickenpox? I do! But now many children don’t have to experience the results of the varicella-zoster virus because of the chickenpox vaccine (lucky them!).

The varicella-zoster virus is a highly contagious DNA herpesvirus. As a primary infection, the virus causes so-called varicella. You might remember this as body rash and itchy blisters that last a few days.

Yet, the varicella-zoster virus actually can remain dormant in our nervous system (called latency) and reactivate later in life. This secondary infection can then lead to herpes zoster, also called shingles.

While chickenpox is usually a non-serious childhood disease, shingles affect adults and can have serious complications and pain. That’s why there is a separate shingles vaccine, too. No one wants to be itchy or in pain, so make sure to get the vaccine!

16. The bacterium Borrelia burgdorferi

Borrelia burgdorferi is a spirochete bacterium shaped like a corkscrew with flagella at both ends. These bacteria live in ticks and can infect humans when bitten by an infected tick.

These bacteria cause Lyme disease, a zoonotic disease where the pathogen jumps from an animal to a human.

Lyme disease is best known for causing a bull’s eye rash. But it also causes fever, headaches and fatigue. Some cases of Lyme disease are asymptomatic and if left untreated can lead to serious neurological or heart issues. Make sure to protect yourself when going hiking and camping.

17. The bacterium Listeria monocytogenes

This bacterium has made headlines, but not for anything fun. Listeria monocytogenes has led to many food recalls because of contamination concerns. It can grow at 0°C, so even refrigerated food can be infected.

Listeria monocytogenes cells are rod-shaped and covered with flagella. This food-borne pathogen causes listeriosis that may result in sepsis, meningitis, or death. It’s especially dangerous for immunocompromised and unborn, which is why pregnant women shouldn’t eat soft cheese or uncooked meat.

Listeria monocytogenes is found in environments where food grows. Contamination can occur during food harvesting and processing. Once inside a human cell, they manipulate it so that the cell propels the bacteria into the next cell.

18. The Epstein-Barr virus

Did you know that the Epstein-Barr virus is one of the most common human viruses? It causes the commonly called kissing disease because we transfer the virus by saliva and bodily fluids.

The Epstein-Barr virus is a DNA herpesvirus with a lipid envelope. Most infections occur in childhood and are asymptomatic or with only mild symptoms. Roughly 90% of adults have antibodies against Epstein-Barr, which means they were once infected with this virus.

When infecting adults for the first time, the Epstein-Barr virus can cause mononucleosis. Symptoms include fever, sore throat and extreme fatigue, lasting weeks to months. You can prevent the spread by not sharing utensils or drinking cups.

19. The bacterium Staphylococcus aureus

One of the best-known bacterial warriors is Staphylococcus aureus and its methicillin-resistant super brother MRSA. These two can infect almost all parts of the human body with their arsenal of virulence factors.

Staphylococcus aureus cells are round-shaped and form grape-like clusters. Most people have this Gram-positive bacterium in their nose or on their skin.

Unfortunately, with certain triggers, this harmless bacterium can become a pathogen. Then, Staphylococcus aureus produces virulence factors, such as toxins, enzymes, and antibody-inactivating proteins. These bacteria can also form biofilms on medical implants.

What about MRSA? Those are strains of Staphylococcus aureus that are resistant to the antibiotic methicillin (Methicillin-resistant Staphylococcus aureus). Antibiotic resistance occurs when bacteria acquire ways to inactive antibiotics and has become a worldwide health crisis.

20. The protozoan Toxoplasma gondii

Love cats? Well, those cats might have a ‘friend’: Toxoplasma gondii. This parasite can be carried by cats and is one of the most common parasites in the world. The infection causes toxoplasmosis which is an important zoonosis.

Toxoplasma gondii is an obligate intracellular parasite. It can reproduce sexually only in cats (called the definitive host) or asexually in any warm-blooded host (such as mice or humans). A cat can become infected by eating an infected mouse, then pass the infection to humans via litter.

Toxoplasmosis infections can occur from eating contaminated food or from infected cat droppings. In most cases, the infection is asymptomatic. However, immunocompromised and pregnant people are at risk for complications.

Which one is your favorite among the interesting microbes?

We hope we could give you a broad overview of interesting microbes and bacteria common in the environment and on the human body. This list of common microbes is meant to raise awareness of how multifaceted the microbial world is.

Yes, some of these microbes cause diseases. But thanks to research, we now have ways to boost our immune systems to clear diseases caused by pathogens or to prevent microbial diseases in the first place with vaccines.

And don’t forget that so many microbes are actually super helpful and fun to look at! Just look at this cute water bear dancing around!

If you have questions about any of these microbes or want to learn more about any player in the microbial world, comment below or send us an email.

And if you want to know more about Rachel and interesting bacteria, follow her on Twitter, or connect with her on LinkedIn.

The post 20 interesting microbes everyone should have heard about 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

Gladly, we learned to use some of these bacterial superpowers to improve our own lives. This means that bacteria and their superpowers are pretty much everywhere you look. You can find their impact in the food you eat, the medicine you take or the bioplastics you use.

So, yes, you probably use microbes and their superpowers daily without even realising. In this article, we listed 20 of the most fascinating bacterial superpowers and how they help not only bacteria but also us.

Bacteria know exactly where they are going

Bacteria have a so-called flagellum with which they can swim in liquids. This flagellum works together with the super responsive chemotaxis system.

This fascinating mechanism helps bacteria understand where beneficial nutrients or harmful compounds are. The bacterium then decides to swim towards or away from that compound. Chemotaxis is thus essential for the survival of bacteria.

Read Chemotaxis helps bacteria move towards goodies

Bacteria are high-speed swimmers

With the above-mentioned flagella, bacteria can move in liquids. When they rotate their flagella, they can swim in one direction which helps them find nutrients or escape harmful situations.

Interestingly, the Olympic recordist for 50 metres freestyle swims 1.17 body lengths per second. However, the bacterium Escherichia coli swims 15 body lengths per second and the tiny Bdellovibrio bacteriovorus swims even 10x faster, moving 160 body lengths in one second.

Read Bacteria wrap themselves in their swimming flagella

Floating veils for large bacteria to attach to and fetch nutrients

Bacteria produce oxygen and give superpowers to everyone

This may sound a little trivial because we take oxygen for granted. But bacteria known as cyanobacteria first produced oxygen on this planet. A large part of the atmosphere’s oxygen today is produced in oceans by these bacteria and other single-celled organisms.

You can also find more on cyanobacteria in this article.

Bacteria can produce electricity

Some bacteria can align into long filaments – so-called cable bacteria. This alignment allows bacteria to produce electrons on one side by oxidizing metals. They can then transport the electrons along the filament. Bacteria on the other side of the filament use these electrons for oxygen reduction.

Thus, bacteria produce an electric current within certain water sediments, which researchers measured. Maybe one day they can use these filaments in some kind of seawater-based batteries.

Read Cable bacteria – unusual bacteria conduct electricity

Bacteria use superpowers to align to the magnetic fields

Some bacteria, like the Magnetospirillum, that live in water, have so-called magnetosomes. These are storage units for iron crystal-like structures. The iron inside can align with a magnetic field and even along the magnetic Earth field.

These aligned magnetosomes then give magnetic momentum to the bacterium. Based on that, the bacterium aligns itself with the magnetic field and can find an optimal location in its environment.

Read How bacteria read and follow the Earth’s magnetic field

Bacteria can reduce and produce gold – highly valuable bacterial superpowers

In gold mines in Australia, researchers found bacteria that form biofilms on gold particles. For example, the bacteria Delftia acidovorans and Cupriavidus metallidurans can reduce toxic gold-ions to elementary gold.

This means that these bacteria are directly involved in the biogeochemical cycling of this precious metal.

Bacteria kill their competitors

To survive and grow, bacteria have learned to outcompete other bacteria and microbes. For this, they developed fascinating nanoweapons that kill their competitors and leave them as the sole survivor.

Interestingly, there are several different of these bacterial nanoweapons, all working slightly differently. Read more about this bacterial superpower:

Bacterial killer weapons as biocontrol to protect plants

Nanoweapons make the killer differences in bacterial siblings

Understanding the type 6 secretion system spike of a bacterial killer machine

Bacteria and contact-dependent growth inhibition: Death on a stick

Bacteria have various superpowers to protect their hosts

Microbes and bacteria live in and around bigger organisms like the human body, plants or animals. They developed fascinating mechanisms to protect their hosts and support them in different ways.

Bacteria might help them digest food, help them grow or fight off harmful intruders. For example, our bodies would not work without the microbiome – all those microbes and bacteria in and on us. Read more about the human microbiome:

How bacteria in your gut microbiome defend pathogens

Bacteria on your hands strengthen your unique skin microbiome

“Follow your gut instinct” – how your gut microbiome influences your mental health

How a healthy gut microbiome protects you and how to keep its superpower

Bacteria and their superpowers light the way

Some bacteria have the superpower to produce light in a process called bioluminescence.

Interestingly, bioluminescent bacteria often live with other organisms in symbiosis. For example, some bioluminescent bacteria occupy the lure of the female anglerfish. This fish also uses them as a fishing rod for hunting.

Bacteria withstand heat and cold

Whether too cold or too hot. Some bacteria really don’t care.

Certain bacteria can survive at temperatures as low as -20°C, which is why they are called hypothermophiles. On the contrary, other bacteria live in hot water steams up to 122°C. Similarly, these bacteria are hyperthermophiles.

These extremophiles have special repair enzymes to keep their DNA and cell envelope intact even at such extreme temperatures. Consequently, some of these enzymes are being used in research and are daily tools in each research lab. Learn more about extremophiles:

Even at the dark and cold bottom of the sea, microbes flourish

Bacteria tolerate harmful radiation

Another extreme-loving bacterium: the radiotolerant Deinococcus radiodurans. This bacterium has very efficient proteins to protect its DNA. Plus, it produces special DNA repair machines. They super quickly recognize and repair any damage in the DNA after exposure to radiation.

With these mechanisms, these extremophiles can survive exposure to ionizing radiation. Some bacteria even survive in the cooling systems of nuclear reactors.

Bacteria go to sleep by forming spores

Some bacteria can form so-called spores which are bacteria “on hold”.

Bacteria go into this state in times of greatest starvation or drought. Their aim is to keep its genetic material safe while turning down all non-essential functions. In this state, bacteria do not have an active metabolism nor do they interact with the environment. They solely wait for better times to come until nutrients become available again.

Bacteria produce some of our favourite foods

Did you know that bacteria produce many of the foods you are consuming? By fermenting sugars to alcohols or acids, lactic bacteria and some yeasts give a delicious taste to common foods like cheese, yoghurt and kefir, kombucha, kimchi and sauerkraut, beer and wine, as well as chocolate.

Reason enough to be grateful for bacterial superpowers to produce amazing foods.

Bacteria can endure high pressure in the deep sea

Researchers found bacteria that can live up to 10 km deep inside the ocean. Yes!

This means these bacteria can endure pressures of up to 100 MPa. But, researchers don’t know yet how these bacterial cells function at such high pressure. However, they think that the proteins inside these bacteria form some kind of super glue-like complexes. This would then make the bacterial content more viscous to endure the pressure.

Read Even at the dark and cold bottom of the sea, microbes flourish

Bacteria produce oil

Many microorganisms, amongst them bacteria, produce natural oils which is why they are called oleaginous microorganisms. Mainly algae, bacteria and yeasts can produce biodiesel, while fungi, and some algae can produce healthy omega-3 fatty acids.

Now, researchers focus on engineering these organisms to enhance the accumulation of produced lipids, biodiesel and omega-3 fatty acids.

Bacteria repair their DNA super efficiently

Bacteria have to endure all sorts of environmental stresses, for example, temperature changes, antibiotics or challenges by competitors. To ensure that under all circumstances, their DNA remains undamaged after an attack, bacteria developed incredibly efficient DNA repair and fixing machines. These machines recognise any small damage in the DNA.

Read

How does Salmonella deal with stress – a journey through the human body

Bacteria destroy proteins to understand the environment

Bacteria nucleate ice and let it rain

Some bacteria can trigger water to form ice crystals at temperatures close to the melting point. One of these bacteria is Pseudomonas syringae.

This bacterium has special proteins on its outer surface that interact with water and triggers ice formation. These bacteria are even used to produce artificial snow in winter sports areas around the world.

Bacteria keep our environment clean

Some bacteria surely love their heavy metals! Many bacteria have special enzymes to reduce toxic metal ions. These bacteria are even used to clean waste in industrial waters or mines and are the basis for green chemistry.

Read Microbial bioremediation: microbes cleaning-up our toxic messes

Bacteria can change our blood types for a short amount of time

Some bacteria live in our blood and when they get hungry, they start cleaving off sugar molecules from our red blood cells. While this is not harmful to us at all, in clinical tests, this may look like a different blood type than our original one.

However, as soon as the body produces new blood cells, they will have our original sugars and therefore our normal blood type.

Read Bacteria changing blood types

Some bacteria are super small

Super small but super powerful!

While bacteria have all these superpowers, I am most amazed by the fact that they are so tiny and yet SO powerful. All these superpowers in such a small box!

To actually see bacteria, we need microscopes. And to have really good photographs of them, we then need EXTREMELY good microscopes. Look at the bacterial cells in the pictures here! They are just about 2 micrometres long…

Thank bacteria and their superpowers

After having read this list of bacterial superpowers, are you even more amazed by our bacterial friends now? Which of these bacterial superpowers is your favourite? Which of them would you like to learn more about? Let us know in the comment section below or send us an email with your question. We’re looking forward to hearing from you!

The post The incredible superpowers of bacteria: unveiling nature’s tiny heroes appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world