And while both viruses and bacteria can live within the same plant, animal or the human body – the so-called host – they can have completely different impacts on them.

A virus infection always has negative effects on the host.

In comparison, the interactions between bacteria and their hosts can be harmful or beneficial for both sides. While pathogenic bacteria harm their hosts, the host usually has a defence system to fight off these harmful bacteria.

However, often both bacteria and host gain from this interaction and form a type of symbiosis. For example, our gut bacteria are getting fed by what we eat. And as a thank you, they produce molecules or hormones that improve our health, immune system and even mood.

In special cases, these symbiotic bacteria even protect their hosts from other harmful microbes like viruses. For example, bacteria in and on our bodies fight off pathogenic microbes.

And the same happens in insects: The bacterium Wolbachia pipientis usually lives within insects and forms a symbiosis with its host. This protects the host from nasty virus infections.

Here we will look at how the bacterium does that and how we could use this symbiosis to fight off viruses ourselves.

Wolbachia pipientis protects insects from viruses

For a virus to grow and spread, it always needs a host and their cells to produce the virus. But when cells produce viruses, they lose energy, nutrients and get sick from the virus or even die. Hence, a virus infection is always harmful to the producing cell and thus the host.

And some viruses can only infect and grow in insects. Gladly, the bacterium Wolbachia can protect insects from some nasty viruses.

One way to do this is that the Wolbachia bacteria stop the virus from entering the insect cells. For this, the bacteria live on the inside of the cell close to the cell membrane. Here, they eat part of the lipids of the membrane and change what the membrane looks like on the outside.

From the outside, the virus cannot recognise the changed membrane and will not bind to it. Like this, the virus will not even enter the cell and the cell is protected from the virus.

Also, Wolbachia strengthens the immune system of insects. This helps the insects fight off the virus to keep them healthy and virus-free.

And some Wolbachia bacteria even eliminate viruses from host cells. However, it is not completely clear yet, how the bacteria achieve this.

Interestingly, different Wolbachia strains are differently effective against different viruses. This is really helpful for us since we could use these bacteria and their superpowers to keep us virus-free as well.

Using Wolbachia to protect us from Dengue fever

We all know how annoying mosquito bites are. But now imagine, when an infected mosquito bites us. The mosquito transfers those annoying toxins into our bodies that give us that terrible itch.

But when that mosquito is infected with a virus, it will also transfer that virus into our body. And unfortunately, many viruses from mosquitos cause dangerous diseases like Dengue fever, West Nile fever, Yellow Fever or Zika. Often, the infected person suffers very badly from this disease or even dies.

This is why researchers want to use the Wolbachia bacteria to protect us from these diseases. For this, they grow mosquitos in the lab and infect them with the Wolbachia bacteria. They then release these mosquitos into the environment – and here we’re talking around 30.000 mosquitos in one go. Can you feel the mosquito itches already on your skin?

These mosquitos then mix with the mosquitos in the environment so that the Wolbachia bacteria spread throughout the whole mosquito population. Now, Wolbachia protects the mosquitos from viruses like the Dengue virus.

And this also means keeping the Dengue virus away from us. And yes, researchers found that fewer people got infected with the Dengue virus after they release their lab-grown mosquitos. What an amazing way to protect us from these nasty viruses and their diseases!

Researchers also try to use these bacteria and their superpowers to protect us from other pathogenic microbes, for example, the Malaria-causing microorganism. I just hope that at the same time, they are looking for ways to make these annoying mosquito bites less itchy…

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

I am fascinated by the impact that these tiny organisms have on our bodies and health, the environment, climate and even food. And I am always amazed by how everything is interconnected; how microbes in the soil can shape the weather and the climate and how microbes in our guts from the food we eat shape both our mental and physical health. Mind-blowing!

With such a huge impact on our lives, microbes even shaped human history, politics, culture and advancement. Due to their integral influence on everything we do, I am convinced that we should all learn more about the fascinating microbes and bacteria all around us.

Sure, this is the main motivation that we write this blog, but there are also great books about microbes that are both educating and entertaining. Here, I want to share my favourite books about microbes and bacteria, written not only to inform but also to make you giggle about what microbes do. I recommend reading any of these microbial books if you’re slightly interested in the microcosmic world or are looking for a present for someone who is.

Disclaimer: some of these links are affiliates and I might make a small profit from your final purchase with no extra costs to you.

I Contain Multitudes: The Microbes Within Us and a Grander View of Life by Ed Yong

This book is already a classic in the microbiology literature. In an easy and funny way, Ed tells the reader how microbes affect our daily lives. After a quick introduction into evolution, Ed talks about how microbes impact our bodies, metabolism or defend us from diseases.

Ed further tells us in a light way that you should not consider your body just as it is, but rather as this multi-organism interacting, communicating and exchanging with the microbes in and on it. After reading this book, you might not see your body the same way as before.

This book about the microbial life is great for:

Everyone who wants to read light stories about microbial life and get a first overview of how microbes have always impacted us and keep impacting everything we do.

Deadly Companions: How Microbes Shaped our History by Dorothy H. Crawford

I started reading this book when the Covid19-pandemic started and felt reassured and scared at the same time. In this book, Dorothy talks about several global pandemics in human history, how these shaped our culture and politics and what we could learn from each one of them.

This book makes it clear that by advancing our communities and cultures, we gave microbes the opportunities to spread amongst us. Like this, infectious disease pandemics have always been part of our history and should be no surprise to anybody.

This book about microbial history is great for:

Everyone who is interested in human history and wants to learn more about how microbes have always impacted human life, especially our politics and culture.

Coloured Bacteria from A to Z from BacterialWorld

We, Noémie and Sarah, wrote and illustrated this book to introduce you to 26 different bacteria, one for each letter. You will get to know bacteria from different environments, their colours, superpowers and how they impact your daily life. In the descriptions for each bacterium, the reader will gain a basic understanding of bacterial cells and growth, microbial fermentation and food production, microbes’ impact on sustainability, antibiotics and health.

With hand-drawn illustrations and a final quiz section, both young children and adults can engage in a relaxing activity while learning about the colourful bacterial world. You can choose among different languages and get the book from Amazon or print the sheets yourself as often as you want.

This microbiology colouring book is great for:

Anyone who has a young child and wants them to learn while colouring. We also found lots of adults who enjoy the meditative activity of colouring and for whom this microbiology colouring book might be a thoughtful present.

Joyful Microbiology Activities Ebook by Justine Dees

Even though microbes are all around us, it is often difficult for students to grasp their omnipresence. The Joyful Microbiology Activities book brings microbiology to your home and shows you with well-explained and hands-on experiments where you can find microbes and bacteria.

A bucket list of the different locations to check out and look for microbes as well as a colourful photo atlas with images of lichens, molds and fungi helps students and curious kids get interested in the world of microbes. Justine also prepared follow-up questions and more ideas for projects and exercises, so parents and teachers can take their microbiology activities one step further.

This book about microbiology activities is great for:

Teachers with science classes as these activities are suitable for class experiments and students of multiple ages. Parents who want to awaken microbiology curiosity in their kids.

The Mind-Gut Connection: How the Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choices, and Our Overall Health by Emeran Mayer

Emeran wrote this book for people who are interested in the little details of how microbes impact our bodies. He talks about the molecular communication between gut microbes and the rest of our body and tells the reader what they can do to positively influence this interaction.

From this book, you will also learn what that gut feeling actually is and why sometimes things just feel right or why you have butterflies in your belly when you’re excited or meet a new love. Emeran also explains why a plant-based diet is the right food for your gut microbes and which food additives you should avoid to stay strong, happy and healthy.

This book about gut bacteria is great for:

Everyone who wants to dig deeper into how microbes impact our health, mood and behaviour and wants to learn in detail about how the human body and brain work.

Invisible Friends: How Microbes Shape our Lives and the World around us by Jake Robinson

This book surprised me a little about its content. Expecting another book introducing the world of microbes, this book instead talks from a social science perspective about how microbes touch our lives. I still haven’t understood the storyline and the key message of the book, but hope it will reveal itself as I get to finishing the book.

Books about microbes and what to learn from them

Here you have six books about how microbes shape your health, the environment and even human history. These are written in languages as jargon-free as possible. And when the authors use technical words, they explain exactly what they mean.

Like this, your background doesn’t matter. As long as you’re interested in the microbial world, you will easily follow these books.

Do you have a favourite book about bacteria or microbes? Make sure to share them in the comments below, so that others can learn more about the fascinating microbial world as well!

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

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

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

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

And so do bacteria.

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

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

How a virus infects a bacterium

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

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

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

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

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

How bacteria fight off viruses

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

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

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

Preventing the virus from binding

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

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

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

Sending out bacterial decoys

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

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

Smart bacteria!

Destroying what is coming in

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

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

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

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

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

Inhibiting the viral genome

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

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

If nothing else works there is still one way out

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

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

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

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

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

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

Multiple lines of defence to protect the whole community

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

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

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

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

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

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

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

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

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

Of phages and bacteria

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

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

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

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

Let me be your phage

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

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

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

I wrap around you

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

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

I protect you

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

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

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

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

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

It seems that another race against antimicrobial resistance just started…

And then I start again

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

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

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

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

Are both of them microbes or germs?

Can we get sick from both?

Do antibiotics work against both? (Spoiler: no they don’t!)

And which ones are smaller again?

I hope I can answer most of these questions in the following overview.

If you want to refresh your memory on what bacteria are and how they function, you should head to the page “What are bacteria“. But here, let’s learn about the differences between bacteria and viruses.

What are the differences between bacteria and viruses?

Bacteria are considered living organisms – viruses not.

Researchers are constantly arguing about this point of view. And I don’t really think there is a right or wrong.

I, however, think that viruses should not count as living organisms. This is mainly due to the following differences between bacteria and viruses:

1. Bacteria can reproduce on their own

Bacteria grow on their own by cell division. Viruses need host cells for their production.

2. Bacteria can produce energy

Bacteria can produce their own energy by metabolising nutrients, meaning digesting food. However, viruses are unable to metabolise anything to make energy.

This also means that bacteria produce cell components that they need so they can grow themselves. Viruses take all that energy from their host.

3. Bacteria can interact with their environment

Bacteria are extremely complex! They can talk to each other and adapt to the environment, importing and exporting molecules. Viruses are not able to adapt to their environment on a metabolic level.

4. Bacteria have a complex cell structure

Bacteria have a cell wall or a double cell membrane. This protects the inner content of the cell from the environment.

The viral envelope is a coat made of proteins and lipids. These lipids come from the host cell that originally produced the virus particle.

5. A bacteria cell is full

The bacterial cell is filled with proteins, ribosomes and all the “stuff” the cell needs to grow, divide and produce anything.

A virus is only filled with the genome, which can be DNA or RNA. Often, proteins inside the virus particle help condense the genome to make it smaller.

6. The host produces the viruses

When a bacterium infects a cell, it still works as an organism. The bacterium can interact with the host cell, metabolise, grow and reproduce.

When a virus infects a host cell, it breaks into its single components: the proteins and the genome. Thus, the virus particle itself does not exist anymore.

The virus then releases its genetic material into the host cell. The virus DNA or RNA then tricks the host cell into reading the virus DNA/RNA instead of the host DNA.

Now, the host thinks it is reading its own DNA/RNA and produces lots of virus complexes. The virus complexes then assemble into full virus particles and leave the cell.

In any case, a virus requires the host to produce the virus.

Without a host, no virus can replicate.

This is why throughout evolution, viruses evolved that are highly infectious. Thus, the virus easily spreads and more and more virus particles can be produced.

As I keep saying, every organism wants to survive.

7. Bacteria can actively move

Most bacteria can actively move or swim with their flagellum. They use this movement to actively look for nutrients or evade dangers.

On the contrary, viruses do not have such a mechanism and require spread by host acceleration. This spread is generally triggered by the virus itself.

For example, one such mechanism is sneezing, which we only do thanks to viruses. When we sneeze, we accelerate the virus out of our bodies. Thus, by sneezing the virus out, it can spread to another host and infect it.

This is why you should cover your mouth when sneezing!

8. There are no “good” viruses

Another important difference between bacteria and viruses is that bacteria actually help our organisms. We can consider these as “good” bacteria.

No virus is actually advantageous for a host, as it always hijacks the host machinery to produce the virus particles. And in most cases, this is deadly for the host cell.

However, a novel study just found a way for how viruses protect their hosts. You can read the article “Love thy host” about this new concept.

9. Antibiotics inhibit bacteria – NO VIRUSES!

Antibiotics only work against bacteria!

This is because antibiotics inhibit cell functions that are only present in the bacterial cell. You can read more about this in the article about antimicrobial resistance.

Because viral and bacterial cells are different, antibiotics do not have the same targets in viruses.

Viral infections can be treated with antiviral drugs, which work differently than antibiotics. Generally, antiviral drugs inhibit certain steps within the virus replication cycle. But this also affects the host replication cycle, which can be quite bad for the host. This is why developing antiviral drugs is so difficult.

10. Preventing infections with vaccines

Virus infection can only be prevented by vaccines. These vaccines recognise surface proteins within the coat of the virus.

Because the surface of bacteria is different, a vaccine against a virus will not work against a bacterium and the other way around.

11. Bacteria are (often) bigger than viruses

Generally, viruses are a lot smaller than bacteria. But as always, there are exceptions. Giant viruses have been found and so were tiny bacteria about the same size as the common virus.

The real difference between viruses and bacteria: which one is alive?

Okay, now it is up to you to decide whether viruses are living organisms or not. What do you think? Are they just parasites hijacking their hosts? Or is that approach so smart that we should count them as living organisms?

I am looking forward to your thoughts in the comments!

The post About the differences between bacteria and viruses appeared first on Bacterialworld.
Bacterialworld - A blog about bacteria: from scientific studies to vivid stories about the fascinating bacterial world

How does this bacterium make sure it won’t be disturbed in its new quiet environment? Easy – it builds a house to protect itself and its siblings.

But a bacterial house is a special one – we call it a bacterial biofilm. And bacteria form a biofilm when they want to protect themselves from their surrounding, form communities and grow and reproduce.

Let’s read on to find out what these bacterial houses are and how they build them.

Why do bacteria form a biofilm?

Just like you need a roof over your head to protect yourself from the outside weather, bacteria form a biofilm that works like a house. And they build these houses from scratch.

A bacterial biofilm has protecting walls and a roof around it. These barriers defend them from all sorts of stresses of chemical or mechanical nature.

And there are so many advantages for bacteria to live in such a house:

• Most antibiotics cannot penetrate biofilm so that bacteria are safe inside.
• Bacteria keep their own nutrients and water and oxygen within the biofilm.
• In the case of desiccation or starvation, they can survive inside.
• Immune cells cannot break through a biofilm, hence bacteria inside are protected from the host immune system. 

So, basically, a biofilm is the master accommodation for bacteria. 

Where do bacteria form a biofilm?

Biofilm is the stuff that you can feel on your teeth in the morning after you woke up. But don’t worry, you easily brush it off your teeth. 

Biofilm is the gloomy stuff that grows on your kitchen sponge and it is the crust in your kitchen sink if you haven’t cleaned it for a while.

Some bacteria can form a biofilm on contact lenses, which can lead to eye infections.

Unfortunately, bacterial biofilms are also one of the major burdens in hospital settings. Here, bacteria form biofilms on medical devices like catheters, joint replacements, implants or pacemakers.

Researchers even found microbial biofilms in 3.2 million-year-old fossils from volcanoes.  

So, generally, bacteria can form a biofilm on any surface.

What does a microbial biofilm consist of?

Many microbes and especially bacteria can form a biofilm. And dependent on the microbial and bacterial species, the biofilm can have a different colour, thickness and texture. 

Generally, biofilms consist of bacterial cells (either only one species or many different ones), as well as other microbes as for example viruses or phages. All these microbes inside the biofilm talk to each other and communicate.

Inside the biofilm, bacteria glue themselves together with so-called extra-polymeric substances. These are big molecules that bacteria produce and excrete.

These extra-polymeric substances are proteins, lipids, sugar molecules or polysaccharides and DNA. And these substances give the biofilm its gloomy or slimy texture.

Interestingly, each microbe and bacterium produces a slightly different kind of polysaccharide. And each of these polysaccharides has slightly different chemical properties. This makes the texture of biofilms from different bacteria also slightly different.

Within the biofilm, bacteria can store everything, for example, metal ions bound to DNA, nutrients like sugar, bacteriophages, oxygen… And bacteriophages even protect the bacteria inside the biofilm.

How do bacteria decide to form a biofilm?

This is an important question scientists are currently trying to understand. As soon as we understand how bacteria regulate biofilm formation, we might be able to develop drugs that prevent bacteria from biofilm formation. 

There is a general model of how bacteria form biofilm.

The general idea is that a few bacteria attach to a surface. For this, they use special adhesion proteins that help stick to the surface.

Now, bacteria want to settle down so that they do not need to move anymore. This is why they stop all movement mechanisms like swimming.

As mentioned already, inside the biofilm, bacteria talk to each other. Like this, they know when they are many together and they can start producing these extra-polymeric substances. By excreting them, bacteria get glued to each other. This helps them completely encapsulate themselves with this hydrogel. 

Interestingly, once in a while, a bacterium spontaneously explodes. Then, the other bacteria use the cellular content (so all the DNA and proteins and lipids) of the dead bacterium to form more biofilm.

Inside such a so-called mature biofilm, bacteria happily grow and divide inside.

However, as soon as nutrients become scarce inside the biofilm, the bacteria need to find a new place to live. Then they will start producing scissors to break the biofilm. And when they activate their swimming and motility motors they can detach from the biofilm towards a new place where they start all over again.

How do we research bacterial biofilms?

This is actually pretty easy, as there are many different stains that specifically bind to bacterial biofilm and make them visible. In the picture below you can see two examples.

These are two different stains that visualise bacterial biofilms. With the stain crystal violet, we can see a purple ring of biofilm on plastic and with congo red, we can visualise the structure of a biofilm.

In the above picture, in the left column (PAK) is a biofilm of the bacterium Pseudomonas aeruginosa. This one does not make much biofilm because you can barely see any violet or red stain. The other two columns are different mutants that produce more biofilm. These biofilms you can recognise by the strong violet or red colours.

With these experiments, researchers can understand under which conditions bacteria form more or less biofilm or whether their texture changes. This will eventually help us get a clearer picture of the fascinating life of bacteria and how to counteract them.

We still don’t understand biofilms very well. And so far we know that some enzymes exist that break a biofilm apart. However, the big goal would be to prevent bacteria from forming biofilms in the first place.

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