The term “sustainability” was introduced. This concept focuses on a world in which we live well within the resources of our planet, today and tomorrow. Based on environmental, social and economic sustainability, the United Nations launched the 17 Sustainable Development Goals in 2015.

The idea was to combine science, society and technology to reach these goals and create a healthier planet and society. Fortunately, among the many contributors to this mission, we also have our tiny friends—microbes.

About the role of microbes in sustainability development

Microbes have existed for billions of years, making up 99% of our ecosystem. They have been breaking down waste, recycling matter and helping maintain balance on Earth long before humans arrived.

Considering that microbes and bacteria influence most of the 17 Sustainable Development Goals, scientists aim to use their superpowers for the sustainable development of our planet. So, let’s look in more detail at how microbes impact planetary sustainability:

Goal 2: Zero Hunger

Microbes are directly and indirectly involved in food production and agriculture.

• Microbes ferment food, increasing its shelf life and nutritional value. Tasty and staple foods like bread, yoghurt, cheese, sourdough, chocolate, sauerkraut, kombucha, cider, idli, beer and wine are indeed products of fermentation
• They fix nitrogen in the soil, naturally improving soil fertility and crop growth
• They help restore carbon in the soil, supporting good farming practices

Some microbes are even food themselves! Many bacteria and fungi are protein sources for both humans and animals. They are grown from agricultural and industrial waste and purified to meet food quality standards. This so-called ‘Single-cell protein‘ or microbial protein is now being explored as an eco-friendly and nutritious alternative to animal-derived protein.

Goal 3: Good Health and Well-being

While some bacteria do cause disease, many others do the exact opposite:

• Bacteria are used as factories to produce life-saving antibiotics, cholesterol-lowering and anti-cancer drugs
• Bacteria can be engineered to produce vaccines and therapeutic agents or transport drugs within the human body
• Probiotic bacteria, those that, when taken in appropriate amounts, are beneficial to human health, improve digestion, boost immunity and enhance our overall well-being

Goal 6: Clean Water and Sanitation

Yes, some bacteria can contaminate water and you surely want to keep these out of your water. Yet, other microbes do the opposite:

• They break down organic waste in water treatment plants
• They can clean up oil spills and even neutralise toxic chemicals, helping recycle water for reuse

Goal 7: Affordable and Clean Energy

One of our global challenges is to reduce our dependence on non-renewable fossil fuels for electricity and energy.

• Bacteria come to the rescue as they produce bioelectricity from organic material, the so-called cable bacteria, conducting electrons across a few centimetres
• Bacteria can convert renewable materials like agricultural and industrial by-products into clean liquid biofuels, offering eco-friendly alternatives to fossil-derived fuels

Goals 9 and 12: Industry, Innovation and Infrastructure & Responsible Production and Consumption

One way to protect our environment is to produce essential materials from renewable sources and recycle waste in industries – an approach called circular economy. Some microbes can degrade organic material, while others produce various chemicals and necessary materials. That is why microbes play a key role in this sustainability area.

• Bacteria can produce the building blocks required to make plastics from renewable materials
• Bio-based plastics are broken down more quickly than conventionally produced plastics, saving our lands and oceans from plastic pollution

Goal 13: Climate Action

Despite ongoing efforts, greenhouse gas emissions remain high due to human activity, leading to adverse climate change. It is expected that the global temperature will rise by 2.5°C by 2050.

• Microbes can capture and convert greenhouse gases like carbon dioxide into low-carbon fuels and useful value-added chemicals
• Some microbes transform carbon dioxide into organic material, which other species use

Since microbes have been maintaining the carbon balance in the ecosystem for ages, they are essential players in curbing climate change. Yet microbes are adapting and changing their behaviour according to climate change. Understanding the relationship between the production and consumption of greenhouse gases by microbes and climate change can help us restore balance sooner rather than later!

Goal 14: Life Below Water

Pollution from human activities is impacting our oceans. We see that the residuals of medicines, caffeine from the coffee we consume, harmful waste from industries, plastics and heavy metals go right into the ocean.

All of this often has a negative effect on marine ecosystems. Gladly, microbes can help break down these harmful pollutants. They use toxic substances as food and convert them into less toxic by-products, water and carbon dioxide. This is called bioremediation, a process that keeps our waters and marine ecosystems clean and healthy.

Goal 15: Life on Land

All life on land needs food. We depend directly and indirectly (through animals) on plants for our everyday nutrition. Plants get their essential nutrients from soil, with microbes having a huge impact on the amount and availability of soil nutrients.

• Microbes help in converting atmospheric nitrogen into a usable form in the soil for plants to use. They also help in making insoluble phosphorous, potassium and sulphur in soil accessible for plants to take up. In doing so, microbes act as biofertilisers as an alternative to chemical fertilisers.
• They are also key players in our food system by preventing the growth of harmful microorganisms that can cause crop diseases, becoming an alternative to chemical pesticides.

Microbes in the ecosystem work in groups to transport chemicals between the atmosphere and land, maintaining a natural balance. However, with human activity, the microbial communities are affected and disturbed. While we still don’t fully understand the extent of their role in ecosystem functioning, it is possible that supporting co-living microbial communities in the environment can help restore the ecosystem.

Goal 16: Peace, Justice and Strong Institutions

Throughout history, the growing demand for better food, resources, health and living conditions has often led human societies to compete—and sometimes even to go to war. But as we’ve seen, microbes offer solutions and services across various spheres of our needs. So microbes can even help us promote harmony and peace – one of the foundations of social sustainability.

How microbes can support achieving sustainability

We’re now beginning to understand the power of microbes in moving towards a greener planet. So next time you want to make an impact on the health of our planet, you can also include microbes in your decision-making.

You could, for example, choose products responsibly produced using bio-based processes, encouraging industries to shift to circular bioeconomy. Composting waste from your kitchen to be used as biofertiliser is a great way to use microbial superpowers on a small-scale level.

There’s still a long way to go in terms of large-scale production and applications, but progress is underway. By recognising and harnessing the potential of microbes, we can make a difference and move a step closer towards the UN Sustainable Development Goals. The future of sustainability might just depend on microbes, their superpowers and the innovative ways we choose to work with them.

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

Consider the scent of a ripe cheese or a glass of wine—these aromas come from bacteria and other microbes. Even less pleasant odours, like old sweat, smelly feet or a mouldy apple, are thanks to molecules produced by microbes.

Let’s explore the fascinating world of bacterial smells, their origins and what we can learn from them.

Microbial smells come from volatile organic compounds

All microbes produce volatile organic compounds as part of their metabolism. These molecules are generally gaseous and vaporous, allowing us, animals and even plants to smell and react to them.

Depending on their environment, the substrate they use, pH, salt concentration and temperature, microbes produce various volatile organic compounds. These can range from simple gases like carbon dioxide or ammonia to organic acids such as isovaleric acid or large and complex steroid derivatives.

For both microbes and us, volatile organic compounds serve as a means of communication and information. As we’ll see, these small compounds play crucial roles in microbial communities and their survival. On the other hand, for us, certain volatile organic compounds signal to our brains that bacteria are present, indicating that something may not be safe to eat or drink.

Some bacterial odorous molecules have a dual nature: indole, produced by gut bacteria from food, gives faeces its characteristic odour. Yet, at low concentrations, indole has a flowery scent and is even used in perfumes.

Bacteria attract animals with earthy smells

Do you recall the scent of fresh rain? That earthy, musty smell comes from a molecule called geosmin, produced by bacteria of the Streptomyces family.

Streptomyces live in the soil, where they produce soil material and form long thread-like filaments. To survive and spread, they use the volatile organic compound geosmin.

When these bacteria release their spores into the soil, they cover them with both antibiotics and geosmin. While the antibiotics protect the spores from other microbes, geosmin attracts small insect-like animals. These creatures eat the spores and distribute them in the environment.

In this case, geosmin signals a food source to the animals as the spores nourish the animals. At the same time, the spores use the animals for transport to new areas. Once conditions improve, the spores develop into bacteria and start forming their filaments in the soil.

Also mosquitoes are attracted to the smell of geosmin in ponds and waters. Here, cyanobacteria produce the molecule, so the mosquitoes decide to lay their eggs here as the bacteria are food sources for the larvae.

Bacteria produce characteristic food smells

Other pleasant and unique bacterial smells come from the fermentation of fruit, vegetables or milk. During this process, bacteria produce compounds that give food not only their characteristic tastes but also aromas.

As an ancient fermentation product, vinegar has a very characteristic sour smell due to volatile organic compounds produced by microbes. Mainly bacteria from the Lactobacillus and Leuconostoc families and some yeasts degrade the sugars of cereals or fruits to produce acids and alcohols.

Also, the fine aromas of wine and cheese come from the many volatile organic compounds bacteria and yeasts produce during fermentation. They include alcohols, aldehydes, ketones, lactones, esters as well as many other classes of chemicals. As you probably know, depending on the origin of the grapes or milk, the ripening temperature and the microbes added, the resulting product can taste and smell entirely different.

However, the unpleasant smell of rotten foods is also due to bacterial metabolic activity. Meat, fish and eggs contain molecules like choline and trimethylamine oxide. Over time, bacteria break these down into trimethylamine. Your brain likely recognises this off-flavour as a sign of food decay, triggering you to reject rotten foods to protect your health.

Bacteria create your unique body odour

Interestingly, your body odour changes based on what you eat and which microbes and bacteria you introduce into and onto your body. Depending on your diet and health, your body secretes different mixes of sweat—generally a watery mixture of minerals, amino acids, fats, urea and antimicrobial substances.

Although your skin produces odourless sweat all over the body, some areas are more hospitable for bacteria and microbes than others. Consider your armpits, where your main body odour originates: They contain more sweat glands and slightly different hair follicles, making them moister and more enclosed. With more water and nutrients available, your armpits are very microbe-friendly.

Consequently, the microbial communities in your armpits can differ completely from the rest of your body. Here, three bacteria—Corynebacterium striatum, Corynebacterium jeikeium and Staphylococcus haemolyticus—have special strategies to survive the high salt content of sweat and even use the urea in sweat as food.

They break down the molecules in sweat into volatile organic compounds that together give each person their unique body odour. For example, sulphur-containing compounds, often with strong onion-like smells, are produced by Corynebacteria.

Our sweat also contains lactic acid and glycerol, from which Staphylococcus and Propionibacteria produce acetic and propionic acid. These molecules directly impact your body odour as they evaporate leaving a pungent smell or supporting the growth of other bacteria. But our smelly sweat has advantages too: After eating citrus fruits, people’s sweat contains limonene, a mosquito-repellent possibly generated by skin bacteria.

Bacteria are responsible for smelly feet

Another significant area of your body directly impacted by bacteria and their smell-creating superpowers is your feet.

Our feet actually contain the highest variety of microbial communities, with Staphylococcus, Corynebacterium and Brevibacterium being the most common. These bacteria feed on skin particles, urea and the amino acids in sweat.

For example, Staphylococcus epidermidis, a normal resident of human skin, degrades the amino acid leucine into isovaleric acid. Unfortunately, this molecule has a powerful, rancid cheese-like odour—the reason for smelly feet.

Fortunately, other bacteria, like Brevibacterium, Micrococcus and Kytococcus, can completely degrade both leucine and isovaleric acid, thus preventing the unpleasant smell. As usual, it comes down to having the friendly bacteria around.

Bacterial smells in your life

As we’ve seen, the world of bacterial smells is fascinating and complex. From the earthy smell of rain to the rancid odour of sweaty feet, bacteria play crucial roles in creating the smells that surround us.

These microbial odours are not just curiosities; they have important functions in nature and human biology. They can act as communication signals between microbes, influence animal behaviour, make our food smell delicious and even impact our unique body odour. So, embrace the microbial world with all its facets, colours and smells!

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

Whatever it was, chances are high that part of your food was fermented by microbes. As exceptionally healthy and tasty as fermented foods are, these would not exist if it weren’t for microbes and their fermentation superpowers.

Yet, microbial fermentation is a lot more than processing food and giving it a new taste or aroma. Indeed, depending on who you ask, microbial fermentation means slightly different concepts.

For once, fermentation is a metabolic pathway in some microbes and organisms. It is an energy-saving way to degrade and metabolise substrates and produce complex and energy-rich fermentation products.

Secondly, microbial fermentation describes the process of preserving food based on the fermentation pathway. For this, we let microbes break apart and ferment food in a controlled manner, eventually producing well-known fermented foods, like yoghurt, beer and chocolate.

Lastly, the industrial process of growing microbes in big cultures is often called microbial fermentation. The goal of this process is for microbes to produce a specific product – and often they do so through the fermentation pathway.

As you can see, the different definitions for microbial fermentation are grounded on the same principle: microbes degrading substrates and making fermentation products from them. Here, we will look closer at the biochemistry of microbial fermentation and explore some examples of where this microbial superpower naturally occurs and how we make use of it.

The biochemistry of microbial fermentation

From the view of a biochemist, fermentation is first of all a metabolic pathway to conserve energy. Most organisms gain energy from opening chemical bonds of molecules. This releases the energy-rich electrons that are bound within the bond. They then save these electrons in other molecules or fuel cellular machineries.

Most microbes have one preferred substrate for their metabolism. For many, this is glucose, the same sugar that our cells preferably burn and degrade. By degrading glucose, they (and us) produce several intermediary products, the most important one being pyruvate. This degradation process sets free several electrons, which microbes save in a molecule called ATP. ATP is the main fuel for microbial growth machines, swimming motors or transporters.

Sometimes microbes find themselves in environments with an excess of their preferred substrate. In this case, setting free all the energy would produce a lot of heat, damaging or even burning the cell. Hence, as an alternative, energy-conserving pathway, they switch to fermentation metabolism.

During this pathway, they degrade the substrate only partly, thus not extracting all available electrons from it. Instead, they use one of the intermediary products and bind it to another molecule in an energy-neutral reaction. This conserves the electrons and energy within the fermentation product.

What makes fermentation so fascinating: Many species have unique fermentation pathways. Depending on their genes, they branch off the fermentation pathway at any intermediate and produce different molecules.

For example, from pyruvate, some microbes produce ethanol, which we use for beer or wine production, and others produce lactic acid, like for yoghurt production. Other microbes ferment substrates like citrate or succinate and produce complex molecules like caffeine or colourful biopigments.

By conserving the high-energy electrons in the fermentation products, microbes produce fewer ATP molecules. Hence, they have less energy available at that moment. But if they need energy later, they can break down the fermentation product to extract the electrons. Often though, their energy levels are so high, that they even export the product to get rid of it.

Fermentation is thus a way for microbes to process molecules and conserve energy. Gladly, we learned to make use of this pathway as microbes help us convert energy-rich substrates into beneficial products.

Microbial fermentation for food preservation

One source of energy-rich substrates are carbohydrate and fibre-rich foods, which is why these are some preferred environments for microbes. By fermenting fruits, vegetables, milk and grains, microbes can grow and spread on seemingly any plant-based substrate.

Gladly, we learned to grow microbes and ferment food in controlled environments, making food fermentation one of the oldest human technologies. Throughout history, many cultures have optimised different fermentation processes and created all kinds of products.

Food fermentation can include adding so-called starter microbes to the food or using those microbes that naturally live in the foodstuff. These microbes break apart the carbohydrate component of the foodstuff to fuel their fermentation pathways.

The resulting fermentation products can be beneficial vitamins, antioxidants or molecules that change the aroma, taste, texture or stability of the foodstuff. The degradation and modification of the food itself and the accumulation of fermentation products, over time, make our well-loved cheeses, coffee, bread, chocolate, beer, wine, kombucha, yoghurt or kimchi.

For example, thanks to microbes, cheese and yoghurt taste and smell differently than the original milk. Coffee and chocolate get their complex and unique aromas only thanks to the microbial fermentation of coffee and cocoa beans.

During fermentation, many bacteria produce strong acids from the original substrate. Thus, the resulting food becomes acidic and sour, which prevents other microbes from growing and spoiling the food. That’s why food fermentation became an efficient way to conserve food. Many vegetables, like cabbages, pickles or olives, are thus preserved into sauerkraut or kimchi, sour pickles and olives, and the like. Also making kombucha, kefir or cheese are ways to preserve the original tea or milk.

When fermenting cereals, yeasts mainly produce carbon dioxide or ethanol. Carbon dioxide, for example, in sourdough bread makes the bread rise. In the beer-brewing and wine-making processes, yeast produces ethanol as well as several beneficial and aromatic molecules that give beers and wines their tasteful and diverse aromas.

About the microbes involved in food processing

Each fermented food has a unique community of microbes that changes with the fermentation process over time. With the rise of one microbial species, the pH of the food might change or a certain substrate becomes available, which might kill one species or feed and thus help another one grow.

In many vegetable-based fermentation products, lactic acid bacteria, such as Leuconostoc, Lactobacillus and Weissella, are the primary microbes. They produce acids which prevent food-spoiling microbes from growing. The acids also give the resulting kimchi and sauerkraut their sour and acidic tastes. On the contrary, in alkaline-fermented foods of Asia and Africa and in bean-fermented foods, such as tempeh, miso or natto, Bacillus bacteria are usually responsible for the fermentation process.

In milk fermentation, bacterial cultures are of two types: Lactococcus, Lactobacillus, Leuconostoc and Streptococcus bacteria that acidify the milk. This denatures the milk and produces yoghurt-type products, such as yoghurt, buttermilk and kefir.

As a second step during the cheese-making process, Brevibacterium, Propionibacterium, Debaryomyces, Geotrichum and Penicillium are added. These bacteria and fungi produce more complex molecules and give the ripening cheese its unique flavour, texture and aroma.

For cereal fermentation, yeasts are the most widely used microorganisms, producing beer, sourdough bread, sake and whiskey. For bread-making, the principal yeast is Saccharomyces cerevisiae. Other Saccharomyces species, as well as Torulaspora, Hanseniaspora and Pichia are responsible for fermenting most cereal-based drinks.

How the human body benefits from fermentation

As we’ve learned above, many fermented foods are full of microbes – as long as the food was not heated or pasteurized. Hence, when eating fermented foods, you also take in the microbes in and on the food. And these are ready to settle in your body, feed off your food and do some more fermentation.

After arriving in your gastrointestinal tract, the microbes start digesting part of your food too. They degrade the plant cell structures of vegetables, fruits, cereals, seeds and nuts as well as non-digestible fibres. This releases sugars which gut microbes ferment to short-chain fatty acids and gases, like methane. These fermentation products have beneficial effects on your digestion, mental and gut health as well as your immune system.

Hence, by eating fermented foods you gain beneficial microbes – some of them are the so-called probiotics. And by eating plant-based foods you give your gut microbes the appropriate food to ferment, which is what makes some of them prebiotics.

But this is not the only place where microbial fermentation takes place in your body. For example, Lactobacillus bacteria are the key players within the vaginal microbiome and their fermentation activities influence the health of women.

Within the vaginal tract, host cells provide Lactobacillus with glycogen. From this, the bacterium sets free glucose and ferments it to produce lactic acid and hydrogen peroxide. These molecules decrease the pH creating an acidic environment within the vagina. This acidity kills some pathogenic microorganisms directly and prevents others from growing. Hence, by feeding residential Lactobacillus bacteria, the body helps them grow and in return they protect it.

Microbial fermentation as a pillar of industrial production

The more we learn about microbes, bacteria and their fermentation pathways, the better we can use their metabolic superpowers for our own good. Especially the biotechnology and food industry are making great use of microbial fermentation.

We now grow microbes in big batches and harvest fermentation products, like bioethanol, lactic acid or vitamin B12. In many cases, microbes grow on plant-based products or even ferment waste into usable and, thus, green products. As you can guess, food fermentation based on appropriate starter cultures is taking place on large scales to produce many of our beloved foods.

As such, microbial fermentation is an essential part of our lives. Not only as a fundamental process in cellular metabolism and thus human health, microbial fermentation has become a key pillar in food production and preservation as well as industrial production.

As a sustainable tool to produce plant-based foodstuffs, pharmaceuticals and fuels, microbial fermentation may even play a crucial role in our journey towards a greener and more resilient future. Just another reason to be grateful to microbes and their fascinating superpowers.

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

Below are a few ways how bacterial research is and continues to make advancements in modern science.

Treatment Courses

Microbiologists working in diagnostic laboratories perform tests on samples which come from either humans or animals.  Doctors or veterinarians analyse these samples to detect the susceptibility or resistance of bacteria to antimicrobial drugs. This kind of research is incredibly important when it comes to discussing the right courses of treatment and future preventative measures that can be taken.

Similarly, biochemists and microbiologists analyse body fluids to identify if and which disease-causing organisms are present. With this bacterial research, doctors can adequately diagnose patients to ensure that they get the right treatment plan in the shortest time possible. Also, the research done by biochemists helps nurses and doctors alike to understand what will and won’t work for certain patients.

Food Health

With microbiological techniques, food preservation is possible. Thanks to modern science and continual research, microbiologists can identify pathogens in food products. These pathogens, if left alone, can end up spoiling the goods and make us sick.

By examining multiple food samples, researchers can determine if contaminants are present and what kind they are. For instance, the type of bacteria that may be found. The results of such examinations help scientists assess the products that are dangerous to human health and those that are not.

Manufacturing Foods

Microbial fermentation helps break down larger food components into simple ones. It is one of the most natural ways for improving vitamin, protein and anti-nutrient content as well as enhancing the flavour and appearance of food.

Fermentation processes are based on microbes like yeast and bacteria that change the food matrix of fruits, vegetables or beverages. Fermented foods include sourdough bread, beers, wine, yoghurt, sauerkraut, kimchi and even cheese.

Medicine

Studying how the human immune system works is incredibly important. To shed light on this question, microbiologists and immunologists work closely together to unravel how pathogens overcome the immune shield of the body. Based on this knowledge, they can then aim to find strategies to fend pathogens off.

Microbiologists are further investigating how “good microbes” help our body function. By better understanding how the human microbiota works and supports us, researchers are aiming to find new strategies to use the microbiota to keep us healthy and fit.

Since the human microbiota also impacts disease and treatment progresses, researchers are currently looking into ways to support the microbiota. This would eventually improve treatments and support the health of people.

The Future of Microbiology

There’s something positive on the horizon regarding the future of microbiology. All of the scientific shifts have brought about new opportunities in different areas of study: food manufacturing, fermentation, medicine and treatment. Such developments will only be beneficial to human life and the environment around us.

Proper, up-to-date Microbiology Laboratory Equipment is an essential part of any microbiology lab no matter the type of research. Advancements in the technology used by microbiologists help accelerate their research and progress in discovering new pathogens and treatments.

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

But have you ever asked yourself where yogurt comes from and how it is made from milk? Do you know why yogurt tastes so sour and yet delicious?

What if I told you that yogurt only tastes like this thanks to bacteria and their superpowers?

Yes, bacteria not only produce delicious chocolate, wine, beer or bread. But it is also bacteria that make yogurt from milk.

Here, we will look at which bacteria produce yogurt and what makes it so creamy, sour but also healthy.

What’s in your yogurt?

Yogurt would not exist if it wasn’t for our bacterial friends. Interestingly, it only takes two bacterial species to create this white creamy dream that we call yogurt. These two bacteria are Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus.

Within milk, these two bacteria live in a symbiotic relationship. This means they help each other grow and survive. And together, they produce delicious yogurt.

These two bacteria make many molecules that give yogurt its characteristic flavor. These include lactic acid and other acids like acetoin, acetate, acetaldehyde. Because of all these acids, yogurt tastes quite sour.

Also, our two bacteria produce exopolysaccharides. Generally, bacteria use these to make biofilms. But in this case, the exopolysaccharides with their long sugar chains make the yogurt creamy and viscous.

Thanks to bacteria and the milk content, there are also a lot of healthy molecules in yogurt: proteins that are rich in energy, calcium, and vitamins B2, B6 and B12.

How is yogurt made?

It seems that all we need to make delicious yogurt are milk, our two bacterial species Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus and the right temperature. We call these two bacterial species the yogurt starter cultures.

But before their superpowers produce yogurt from milk, the milk needs to be prepared. This is basically to get rid of all the other stuff that we don’t need.

So, to kill all other microbes that might spoil our yogurt, the milk is heated to 95 °C. You might know this process as pasteurization.

After the milk cooled down to about 40 °C, our two starter bacteria are added. Next, the mix is filled into cups and sealed. The cups are then stored in a warm room – something researchers call incubation. During this incubation time, the bacteria can get to work and use their superpowers.

This means that our two bacteria start a process called microbial fermentation. They break down the milk sugar lactose and produce lactic acid and other acids.

Due to all the acids, the pH of the milk drops and it becomes sour. Now, the acids denature the milk proteins – this is the same process that you see when you heat an egg: it becomes harder and loses its fluidity. The milk becomes more viscous and gets a gel-like texture and creaminess.

Why is yogurt good for you?

We already saw that yogurt has a lot of good stuff and some studies showed that it is healthy for us because of all these molecules. But how do these vitamins, proteins and short-chain fatty acids impact our health?

For example, yogurt stimulates the immune cells that are in our guts. This improves our immune system so that it can better fight bad intruders.

Our two starter bacteria also break down some of the milk proteins and produce so-called bioactive peptides. Our guts like these peptides a lot. Hence, it transports them into our bodies where they have health benefits.

Also, the sugars in yogurt are prebiotics. This means they are the right food for other bacteria that live in our guts and that keep us healthy.

Plus, yogurt is full of protein that our bodies need to grow muscles and stay strong. Interestingly, yogurt protein has two important fractions: whey and casein protein.

The whey protein is considered a “fast protein”. This means, our body digests this type of protein faster which gives us energy immediately after eating yogurt.

The other fraction is casein or the “slow protein”. This type of protein clots in our stomach because of the acids. But our body can digest this protein clot only slowly. Hence, the casein protein gives us energy even up to 7h after eating yogurt. Like this, yogurt helps with satiety so that in general we need to eat less.

Lastly, the short-chain fatty acids in yogurt have lots of health benefits for us. They regulate the blood glucose level, insulin resistance and inhibit our appetite.

Now you have a lot of reasons to include yogurt in your daily diet plan!

What is probiotic yogurt?

Researchers found that the two starter bacteria Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus do not survive the acidity in our stomachs. Hence, they do not arrive in our guts and have no impact on our gut microbiota.

However, yogurt is a great vehicle to transport other probiotic microorganisms into our bodies. Probiotics are organisms that “when administered in adequate amounts, confer a health benefit on the host”. Also, probiotics need to be safe, well-characterized and stable while the yogurt is waiting on the shelf to be eaten.

Hence, many yogurt companies now add beneficial probiotics to yogurt. These are bacteria like Lactobacillus casei, Lactobacillus acidophilus or Bifidobacterium.

These bacteria have beneficial effects on our digestion and immune system. They help the right bacteria in our guts to grow, meaning they keep our gut microbiota healthy.

For example, in one study, researchers added a Lactobacillus casei species to yogurt and gave it to children with acute diarrhea. After a few days, these children had fewer symptoms and less abdominal pain thanks to the yogurt mix.

Is (probiotic) yogurt on your diet plan yet?

Here, we looked at two new superhero bacteria that produce the fermented creamy white dream. Even though they might not survive the passage into our bodies, they produce a lot of healthy molecules for us. Hence, they have an indirect health benefit on our bodies.

Plus, yogurt is a great vehicle to transport other probiotic bacteria into our bodies. And it seems that by eating yogurt regularly you can indeed change your gut microbiome and bring in some helpful bacteria.

So, thank bacteria for their superpowers and for providing us with this delicious food!

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

And with an increasing global population, it will be important to find ways to increase the world’s food supply in sustainable ways.

Adding microbial communities, called biofertilizers, to soil can increase crop yield and plant health all without adding any toxic chemicals.

Lucky for us that microbes once again can help save our planet by addressing our global food crisis.

A global challenge

While the global population grows to almost 8 billion people, the land for agriculture remains limited. One way to meet this growing challenge is to increase the quantity of food produced on the same amount of land.

In the past, farmers added expensive chemical fertilizers to their crops. These meant to increase important soil nutrients – specifically nitrogen and phosphorus – and help the plants produce more food.

Unfortunately, these chemicals enter and pollute nearby water systems, harming our health as well as the health of our planet. Plus, producing these chemical fertilizers releases greenhouse gases that add to climate change.

One sustainable method to increase crop production is to add microbial communities to agricultural plants; so-called microbial biofertilizers.

Microbes as biofertilizers

These biofertilizers are soil microorganisms that provide nutrients, stimulate growth, and improve plant health. Also, biofertilizers are more sustainable, less toxic, and cheaper than traditional fertilizers.

Here, we will look at what biofertilizers actually do and how these microbes work for the plants.

Helping plants get nutrients

All living organisms need nitrogen, but not all nitrogen found in the soil is in a useable form. In fact, nitrogen is a major limiting nutrient for plants because most nitrogen in the soil is in a form that plants cannot use.

Hence, microorganisms first need to “fix” the nitrogen and then convert it into a usable form. For this, bacteria make an enzyme called nitrogenase that converts nitrogen from atmospheric nitrogen (N₂) to ammonia (NH₃). Now, plants can absorb this nitrogen form and use it for energy and growth.

Some plants have evolved to work with bacteria to make it easier for them to absorb the fixed nitrogen. For example, the roots of certain legume plants include special root nodules. In these live nitrogen-fixing bacteria called Rhizobia. When chickpea seeds were grown together with these bacteria, their yield increased 250%. Also, adding Bradyrhizobium species to mung bean plants promoted plant growth and yield and plants had a higher tolerance to insecticides.

Cyanobacteria also help plants fix nitrogen. When wheat plants grew together with cyanobacteria species Calothrix ghosei, Hapalosiphon intricatus, and Nostoc species, they grew higher and had more grain. Additionally, co-cultivation with Nostoc or Anabaena species resulted in increased root length and wheat plant nitrogen levels. Cyanobacteria are important nitrogen-fixing bacteria in aquatic environments too, especially for rice production.

Helping plants grow

Besides nitrogen, soil bacteria can provide plants with many nutrients, vitamins, and plant hormones. These are called phytohormones. Phytohormones promote plant growth by acting as signaling molecules to regulate plant metabolism and stress response.

When Rhizobia bacteria grew together with the mustard plant Brassica juncea and produced phytohormones, the plants grew better. Also, in corn (maize), inoculation with Azospirillum brasilense resulted in increased plant growth correlated with elevated phytohormone levels.

Over 80% of Rhizobia bacteria produce the major phytohormone indole-3-acetic acid (IAA). This phytohormone regulates plant growth, cell differentiation, and stress response. Thus, when bacteria secrete indole-3-acetic acid, it promotes root growth. This helps plants take up nutrients better.

In addition to a single bacterial species, communities of microbes help plants stay healthy and grow. Archaea, bacteria and fungi all associate with the roots of plants and synergistically provide nutrients to the plant. Researchers are studying these communities to understand important microbial interactions. The aim is to design microbial communities specific to each crop that promote higher crop production in the future. Just think, one day you could order a biofertilizer optimized for your unique climate, soil, and plant!

Fighting plant enemies

Not only do microbes provide their hosts with nutrients to promote growth, they also protect their hosts from deadly pathogens. Especially fungal pathogens are known enemies that threaten plants.

For example, Pseudomonas and Bacillus strains release toxic chemicals such as hydrogen cyanide to inhibit fungi that infect coffee plants. Other Bacillus strains produce antifungal molecules and simultaneously increase corn (maize) seedling growth. The bacterium Ochrobactrum anthropi TRS‐2 can fight fungi, and application of this bacterium on tea plants decreased brown root rot caused by the fungi Phellinus noxius.

Some bacteria even produce biofilms on the roots of plants as a barrier against invading fungal pathogens!

Agricultural crops are also prone to infection by nematodes, commonly called roundworms. Nematophagous bacteria can deter nematode growth by sending out toxins, and competing for nutrients. For example, Pasteuria penetransbacteria infects nematodes, while Pseudomonas strains can produce antibiotics against nematodes that infect potato plants. No matter the pathogen, soil bacteria have evolved ways to promote and protect their host plant.

Microbial biofertilizers assist our global challenge

As the world’s population increases, we will need sustainable and inexpensive ways to increase agricultural production. Just as microbes add nutrients and flavors to our meals, bacteria can nourish our crops as well. Plus, biofertilizers are a greener, healthier, and less expensive alternative to traditional chemical fertilizers.

So, next time you go out into your garden, think about adding some biofertilizers like compost or manure instead of chemicals to help your fruits and vegetables grow.

Along with bacteria, we can help save the planet!

Take away messages from this week’s article:

• The increasing human population is creating a global food crisis 
• Microbes can act as biofertilizers by providing important nutrients and helping promote plant growth
• Microbial biofertilizers are a sustainable and inexpensive way to increase global food production

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

Many organisms learned to produce bioethanol: plants, fungi and yes, also bacteria. And they can use many different substrates to do so: plants and wood or food waste. You probably know the alcoholic smell of over-ripe fruits or juices.

So, why not use this bacterial superpower to help us with our energy crisis? Let’s look at another possibility of how bacteria could save the health of our planet by producing alternative energy sources.

Where does bioethanol come from?

Microbes can produce ethanol in a process called microbial fermentation. This means that they break down sugars to produce ethanol and energy for the cell.

This process also takes place when producing wine and beer or rising bread dough.

But to produce biofuels, it gets a bit messier because the substrates often come from food or plant waste. And often, uncharacterised microbial communities cover them.

In these cases, the microbial communities work together to make use of all the components of the waste.

For example, the walls of plant cells contain very rigid and long sugar molecules – so-called polymers. Certain bacteria can break down these long polymers into single sugar molecules.

Then, other organisms – often yeast strains – produce ethanol from the sugar molecules in the fermentation process. And when producing beer or wine or rising bread, it is usually our good old friend the baker’s yeast that produces the ethanol for us.

But when it comes to producing bioethanol, we need a lot of it and we need it fast. How lucky are we that one bacterium produces bioethanol a lot more efficiently than yeast strains?

Meet Zymomonas mobilis – the fastest bacterial bioethanol producer.

Why does Zymomonas mobilis not get drunk?

From every single sugar molecule, Zymomonas mobilis produces two ethanol molecules. As you can imagine, Zymomonas mobilis produces a lot of ethanol during its lifetime. So much, it would get you and me super drunk and would damage our bodies irreversibly. But ethanol is not just toxic for us – it also is for bacteria.

Ethanol is a so-called chaotropic compound. This means it disturbs the organisation of biological macromolecules. Hence, proteins and DNA can get disrupted and lose their function. Like this, the bacterial outer envelope gets completely disorganised and bacterial cells lose their stability.

Because of that, most bacteria cannot stand the tiniest bit of ethanol as they get drunk and become intoxicated.

But not Zymomonas mobilis.

This bacterium can live on ethanol without losing it. It knows very well how to protect itself from the toxic effects of ethanol.

Zymomonas mobilis carries a special sugar in its outer envelope. Because of these sugar molecules, a water layer surrounds the membrane. And this water layer blocks the ethanol from coming into contact with the membrane. Hence, the sugar-water shield protects the membrane and the bacterium.

Also, Zymomonas mobilis produces a biofilm that blocks ethanol from entering the bacterial community. And researchers also found that when Zymomonas mobilis lives in biofilms, it produces even more ethanol.

This sounds like something to create communities of Zymomonas mobilis biofilms that efficiently produce ethanol on an industrial scale.

Zymomonas mobilis as an efficient biofuel-producer

Researchers are already on it to use this superhero bacterium to tackle our energy crisis. They are looking into feeding Zymomonas mobilis different substrates from food leftovers or plant waste.

Unfortunately, our superhero bacterium cannot break down the long sugar polymers from plant cells. This means that for industrial processes, the food or plant waste needs to be pre-treated to break down the polymers. But this step also increases costs and processing time.

An alternative is to use other bacteria or microbes that can break down the polymers into single sugar molecules.

Zymomonas mobilis then uses its very efficient sugar transporters to import the sugar molecules into the bacterium. Now, the bacterium can ferment the sugars and produce bioethanol.

Can you see how this is yet another example of how microbes feed each other?

So far, this process is not optimised for huge-scale industrial applications. But it seems clear that it might be bacteria that help us with yet another crisis.

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

Microbes are necessary for many of our favorite foods, such as bread, cheese, and chocolate, and the beverages we wash them down with, like beer and wine!

With the holidays fast approaching, let’s look at how microbes play a central role in the holiday menu.

Microbes Help Make What You Eat

Microbes are everywhere, including your food. Not only known for food spoilage, but some microbes also help preserve and add flavor to foods. In a process called microbial fermentation, microbes convert sugars in foods into different compounds, such as alcohols or acids.

Bread

Microbes are also necessary to produce our foods. Many holiday meals include special bread that depends on the microorganism yeast. Bread making usually uses the yeast Saccharomyces cerevisiae to eat the sugar in bread dough to make carbon dioxide (CO₂) bubbles that expand and rise the bread.

Microbes can also give bread some of its flavors. Sourdough bread gained popularity during the COVID-19 pandemic because of the ease of culturing the sourdough yeast, called a starter. Sourdough’s unique flavor comes from the starter’s mixture of yeast and lactic acid bacteria. These Lactobacillus bacteria ferment and produce lactic acid, which gives sourdough that ‘sour’ taste and helps to prevent the bread from going stale.

Cheese

After making your holiday loaf, you will need to put something on those slices. Cheese is one of my favorite bread sidekicks and appears on many holiday menus.

Like bread, cheese requires a starter culture of bacteria to convert the sugars in the milk into acids such as lactic acid. Next, during cheese ‘ripening,’ added secondary microbial cultures give each cheese its unique flavor and texture. These secondary cultures can include bacteria, yeast, or even mold, like in the case of blue cheese, and all help produce those much-loved flavors.

Microbes Help Make What You Drink

Bread and cheese are delicious, but they are even better when paired with a nice beverage. Luckily, microbes help make some delicious drinks as well.

Beer

One of the oldest microbially-made drinks is beer. Beer dates back over 5,000 years, though recent evidence suggests people first fermented beer over 13,000 years ago! Like today’s beer, ancient cultures ground grains in large vats and exposed them to yeast that would eat the sugars and ferment it into alcohol and CO₂.

This process adds flavor to the drink as well as many nutrients and essential B vitamins. Most importantly, the alcohol kills possible contaminates and makes the water safe to consume. Adding hops aids its antimicrobial activity by inhibiting Gram-positive bacteria.

While the first beers relied on wild yeast strains naturally found in the air and dust, today’s brewers add specific strains of yeast for desired alcohol and flavor profiles. Or they might add bacteria. Many Belgian ales have Brettanomyces yeasts to produce their notable sour flavor, while German Berliner Weisse beers are fermented by Saccharomyces cerevisiae and Lactobacillus bacteria.

Wine

If beer is not your thing, possibly you will want a nice glass of wine this holiday season. You can thank microbes for that too.

Wine is produced when yeast ferment grapes, yielding both alcohol and CO₂ like for beer. Microbes are important not only for fermenting grapes, but specific yeast, fungi, and bacteria are important for keeping grapes healthy.

Additionally, some fungi are critical to produce specific wines. Botrytis cinerea is a fungus that helps to dry out and concentrate the sugars of a grape through a so-called ‘noble rot’. These grapes produce a sweet dessert wine called a botrytized wine. However, if Botrytis cinerea infects grapes during moist conditions, this ‘gray rot’ destroys the grape crop. Thus, having the right microbiome is important for agriculture just as it is for humans.

Kombucha

If you don’t like beer or wine, you can always try kombucha. This non-alcoholic beverage is produced from acetic acid bacteria and yeasts called a “tea fungus” that ferment tea. The bacteria and yeasts live symbiotically in a biofilm clump called a scoby (“symbiotic culture of bacteria and yeast”). Here, microbes work together to convert the sugars into acids that give the tea a nice tart flavor.

And don’t forget dessert!

Cakes, candies, and cookies are all staples of the holidays. These sweet treats would not be the same without microbes to add flavor and rise.

My favorite sweet, chocolate, comes from cacao beans that are initially fermented for many days by wild yeasts and bacteria. This process breaks down the beans and leads to the production of those oh so yummy chocolate flavors. Just another reason to love microbes!

Welcome Microbes to Your Next Meal

Microbes are vital for giving us so many of the foods and flavors we love. From foods like bread, cheese, and chocolate or drinks like beer, wine or kombucha, microbial fermentation plays an important role in many of our favorite dishes. Fermented foods give us flavors, vitamins, and additional food preservation.

These foods can also help maintain healthy digestive systems. Yoghurt, which is another fermented milk product, contains beneficial bacteria that can help maintain a balanced microbiome.

Not only do microbes help save the planet, but they also save our meals and our health too. So this holiday season, remember to incorporate microbial dishes into your menu.

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

No, but this is pretty much what happens there.

Okay, they might not sit at a table with napkins in their laps and fork and knife in hand. But bacteria do share food with each other and even feed each other with their leftovers. 

Not sure, how that might work? 

Read on to find out!

What’s in your plant food?

If you are like most people and eat a healthy balanced diet, you will probably eat a lot of plant products, including vegetables and fruits.

But think about what plants are actually made of: Their cell walls are extremely rigid and sturdy because plants need to be stable to withstand different weather conditions. So, to stabilise a vegetable or fruit, they have complex walls that we can barely digest.

And yet, they are some of the best foods you can eat…

While our own digestive system is struggling to break down plant material, we can always rely on the microbial friends in our guts. They have the necessary tools and superpowers to break up plant material, digest plant food and help us get the best from it.

But none of them can do it on their own. Also, bacteria work together and share their food to achieve that.

Let’s look at how food-sharing works between bacteria and which plant components they are digesting for us.

Arabinogalactan – a complex glycan from plants

To stabilise plant cells and make them sturdy, long and complex molecules are part of most plant cells. These are often glycans that are complex polymers with one main chain and many different side-chain branches. 

And one of these complex plant glycans is arabinogalactan – or short AG.

AG consists of very long main chains made of the same sugar molecules. And each sugar molecule consists of a ring of 5 carbon atoms. Now, these carbon atoms link to carbon atoms within the same sugar but also to carbon atoms in the next sugar.

So, within the main chain, the sugars are all linked to each other via the so-called 1,3-bond. This means, that the carbon atom at position 1 links to the next sugar molecule via the carbon atom at position 3. And between these two carbon atoms sits an oxygen atom. 

Okay, so far for the main chain.

The side chains consist of different sugar molecules. Hence, the bonds between them are different. 

Plus, the side chain is connected to the main chain via a different bond – the 1,6 bond. This means, that the carbon at position 1 from the sugar molecule of the side chain binds to the carbon at position 6 of the sugar molecule of the main chain.

Since these side chains have different lengths and lots of branches, the structure of the AG gets so complex. This is what ultimately makes it so difficult for our digestive system to break them down. We just don’t have the tools for that.

Enter our microbial friends in our guts.

Bacteria degrade complex plant polymers

Since this complex AG polymer is basically in every plant cell, we are eating a lot of it. And somehow we seem to be able to digest it. So, researchers were curious about what happens to this glycan in our guts.

And they knew already, that bacteria in our guts have really cool tools and scissors to break up complex plant sugars and glycans.

This scissor sits on the outside of a bacterium. Here, it directly chops off a piece of sugar when it comes into contact with a plant polymer.

And directly next to the scissor sits a transporter. This immediately takes the chopped off sugar molecule and imports it into the bacterium. Now, the bacterium uses this piece of sugar for energy and growth. 

One of the bacteria that break down AG in our guts is Bacteroides cellulosilyticus. Let’s call this one the Bacell-bacterium. 

These Bacell-bacteria have special scissors that cleave off the side chain of AG from the main chain. Plus, they have another set of scissors to chop off the last sugar molecule from the side chains.

However, they cannot break up the rest of the side chain. Hence, this leaves some valuable sugar chains lost in the deepest corners of our guts. 

But gladly, other bacteria pick up these yummy sugar sources and are grateful for that share of food.

Bacteria get their share of food

Researchers found that the bacterium Bifidobacterium breve uses these released sugar chains. Let’s call this bacterium the Bif-bacterium. 

Generally, the Bif-bacterium does not have these advanced scissors to break down complex glycans. But it can pick up and degrade released sugar chains from other bacteria. 

Researchers found that when they fed the Bif-bacterium with AG, it did not grow alone. However, they then added the Bacell-bacterium and fed them with AG. Now, the Bif-bacterium was growing.

This meant that the Bacell-bacteria break down certain pieces of the AG and share the leftover food with the Bif-bacteria. Since Bif-bacteria have the right scissors to break down smaller sugar molecules, they can use these now and grow.

Next, the researchers looked at what both bacteria produced from the AG.

Bacteria share food with each other and keep us healthy

They found that the Bacell-bacteria alone produce some short-chain fatty acids from the AG. These short-chain fatty acids are very helpful for our body and keep us healthy.

Yet, when the Bif and the Bacell-bacteria grew together with AG, they produced even more diverse short-chain fatty acids. This meant that the interaction between the Bif- and the Bacell-bacteria itself can be understood as a probiotic – they are healthy for us. And it also means that AGs are prebiotics – they feed healthy bacteria.

Interestingly, also other bacteria get their piece from this interaction: The probiotic bacterium Lactobacillus reuteri (Lacto-bacterium) also plays a role in sugar degradation in our guts.

The Bif-bacterium produces a molecule called 1,2-propanediol from AG. Now, the Lacto-bacterium can pick up 1,2-propanediol and make more short-chain fatty acids from it. And this also helps the Lacto-bacterium grow and keeps our gut healthy. 

So, when bacteria share food with each other, everyone wins!

Help your bacteria share food and you keep yourself healthy

From this little story, I hope it became clear again, that you are what you eat. By giving your bacteria the right food, they can feed each other so that they grow. And when the right bacteria grow in your gut, they will defend you against harmful pathogens and keep you healthy. 

So, yes, keep being nice to your bacteria! ?

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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.

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