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

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

Yes, the bacteria in your gut have certain superpowers that we benefit from. They help us digest food, keep us mentally and physically healthy, activate our immune system and keep out harmful pathogens.

Here, we will explore some of these fascinating aspects of a healthy gut microbiome, what it is, what it does and how you can keep its superpowers. Learn more about what a healthy gut microbiome actually means and does for you.

What is the gut microbiome?

The gut microbiome consists of all microbial communities that live in your gastrointestinal tract. In there, you can find many diverse players, like bacteria, viruses, fungi and archaebacteria. Here, we will focus on the bacterial members of our gut microbiome, but don’t forget that they all work together to achieve their goals.

Every person has their own unique gut microbiome. So, everyone – depending on their socio-economic state, diet, age, geography, drugs, sleep and other environmental substances – has their own special microbial friends. And studies showed that each person’s gut microbiome is stable over time, even after antibiotic treatment, acute intestinal infections and modified diets.

When you think about it, your gut is a very welcoming environment for most bacteria. It is always about 37 C, a lot of food from your meals and many other microbial friends to party with.

Surprisingly, many bacteria are unable to grow in the lab, so researchers still don’t know much about them. That’s because we don’t know what these gut bacteria need to grow outside of the gut. Yet, researchers found their bacterial DNA in human guts, so they must be living there, somewhere…

Our gut microbiome plays many roles in our wellbeing

In comparison to other microbial niches within our bodies, the gut microbiome is probably best characterized. However, many studies also try to characterise the microbiomes of other parts of our body, as different skin areas. Imagine different organisms living on your feet than on your hand or under your armpits, ears or even eyes.

The reason why researchers mainly study the gut microbiome is due to the accessibility of samples. The sample comes out of your body, so you can directly use it without swapping a person.

Second, the gut microbiome plays important roles in many diseases. So, a lot of research focuses on understanding the interplays between these diseases and the gut microbiome. The aim here would be to find cures or intervention therapies.

How do gut bacteria support our health?

While researchers are still trying to unravel the full impact of our gut microbiome on our health, we are understanding it better and better now. By now we know that a few important players in our gut microbiome are a sign of good health. These are Faecalibacterium, Roseburia, Lachnospiraceae, Eubacterium and Akkermansia muciniphila.

For example, our friendly gut bacteria help us in food digestion. Some of the foods that we eat, we can’t fully digest ourselves, like many complex sugars. In this case, the bacteria in our gut break down these indigestible molecules and produce compounds that we otherwise would not have.

For example, they produce gasses and certain molecules called short-chained fatty acids. While the gasses eventually make their way out of our gut, the short-chain fatty acids play important roles in our overall well being.

These molecules have a positive impact on our mental health, while they also strengthen the gut wall to keep our gut intact. Short-chain fatty acids also strengthen our immune system and help our friendly gut bacteria to grow better. On the other hand, pathogenic bacteria do not like short-chain fatty acids and have thus a harder time settling down in our guts.

Yet, our friendly gut bacteria protect us actively from harmful pathogens that can cause diseases. For example, they fight pathogenic bacteria with harmful killer weapons or produce compounds that are toxic to them.

Also, don’t forget that after a single pathogenic bacterial cell somehow made its way to our gut, it encounters billions and trillions of bacteria that already live there. So, altogether, our microbiota developed many strategies to ensure that any invading pathogenic bacterium feels unwelcome in this environment.

What does an unhealthy gut microbiome look like?

However, once in a while, our gut microbiome seems to be “out of balance”. This can often lead to disease or irritation.

While researchers still don’t know exactly, what the “normal” gut microbiome actually looks like, they are analysing the microbiomes of people with specific diseases. For this, they compare the gut bacteria from people with a disease with the gut bacteria from people that do not have that disease.

And very often, they find that healthy people have a broader variety of bacteria living in their guts. So, somehow all these different bacteria grow together and work as a team to keep us healthy.

This means, one or two bacterial species are often more present in the microbiomes of people with diseases. For example, the bacterium Faecalibacterium prausnatzi likely has beneficial effects on our gut health. However, unhealthy people often have less of this bacterium.

This shift in our microbial gut flora is what researchers call gut dysbiosis. However, whether this shift is the cause or the result of the disease is still not always clear.

Generally, people with gut dysbiosis have fewer bacteria that produce short-chain fatty acids. At the same time, they have more bacteria that degrade the mucus layer of the gut. And the mucus layer is what keeps our gut healthy and intact, so its degradation is usually not a good sign.

Many chronic diseases seem to be associated with gut dysbiosis. For example, type 2 diabetes, obesity, inflammatory diseases or Crohn’s disease, but also mental disorders like depression. However, the exact links are not clear yet.

How can I keep a healthy gut microbiome?

Researchers agree here: You are what you eat!

Diversity is key when it comes to our gut microbiome. This means that you want to make sure ALL of your bacteria stay happy within your gut. So, to keep your diverse bacteria with you, it is vital to eat everything.

Your aim should be to grow those bacteria within you that produce short-chain fatty acids from your food. And for that to happen, you should feed them foods that are high in complex sugars, like fibres.

Also, some studies suggest that certain food additives impact your gut bacteria negatively. These include for example emulsifiers, which work like soaps and kill certain bacteria. Also, stabilisers were shown to induce colitis in animals and artificial sweeteners led to changes in the microbial composition and glucose intolerance in mice.

Most importantly, antibiotics have drastic effects on our gut microbiota. Researchers actually think this is one of the main causes of our modern chronic diseases.

What are probiotics and prebiotics?

The FAO/WHO considers “live microorganisms which when administered in adequate amounts confer a health benefit on the host” as probiotics. These are mainly bacteria that usually live in our guts and that have been well characterised by researchers before.

Interestingly, probiotics do not stay in your gut for a long time. This means to have a long-lasting effect, you should keep eating them regularly.

For example, a probiotic strain of Escherichia coli can slow down the growth of a pathogenic Salmonella strain. Escherichia coli has transporters that specifically bind iron and uptake iron into the cell. With this mechanism, the Escherichia strain uses the iron of the environment, so that there is none left for Salmonella. Because Salmonella and all other bacteria need iron for growth, Salmonella has trouble growing and colonising the gut environment.

Foods with probiotics are for example fermented foods, like yoghurt, kefir, kimchi, kombucha or fermented vegetables. But beware here, as not all of this food actually contains approved probiotic strains.

And to feed your gut bacteria the right food, make sure to eat enough prebiotics as well. They are basically the food for your gut microbiome party.

These include foods that your body cannot digest, which is why your gut bacteria take care of them. Like this, prebiotics promote the growth of probiotic bacteria in your gut. You can mostly find prebiotics in fibres as complex sugars in many vegetables, especially in asparagus, onions or garlic.

Lastly, synbiotics are combinations of probiotic bacterial strains and prebiotics. This basically means that the right bacteria come and bring their own food to your gut party.

Help your gut microbiome help you

So, by eating the right food, you can make sure the right, helpful bacteria grow and live in your gastrointestinal tract. And as a thank you for feeding them, they make sure to protect you and keep you healthy. Great bacteria and their superpowers.

The post How a healthy gut microbiome protects you and how to keep its superpower appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world