What is a microorganism?

A microorganism, also called a microbe, is a living organism that is microscopic in size and invisible to the naked eye. Bacteria, fungi, yeast, protozoa, algae and viruses are all examples of microorganisms.


Bacteria, a prerequisite for life

Bacteria are one kind of microorganisms that are exceptionally important for human health. They were the first form of life to “populate” the Earth some four billion years ago, and still today they dictate the conditions for our existence. Throughout evolution bacteria and humans have co-existed. Lactobacillus reuteri is one important bacteria that has developed in symbiosis with us.

Bacteria can be found everywhere, for example in soil, water, snow and even in volcanos. Some bacteria live in and on other organisms like animals and humans. Directly after birth the newborn baby is almost sterile but very soon bacteria start colonizing every part of the body – the skin, the mouth and most importantly the gastrointestinal tract. The number and diversity of bacteria continue to increase until the age of three, when it resembles the composition in an adult and then, more or less, remains the same throughout life.

Research has shown that Lactobacillus reuteri is a species of bacteria that has developed a mutualistic relationship with its specific host over millions of years. In other words, throughout evolution certain strains of Lactobacillus reuteri have made their home in the specific environment that is found in the human gut. Read more



Bacteria in the human body

Earlier it has been widely cited in literature that humans carry ten times as many bacteria cells as body cells. However, new findings suggest that the number of bacterial cells are actually more or less the same as the number of human cells. These bacteria are called the human microbiota and they are extremely essential for human health.

Researchers are eager to understand the importance of the human microbiota, but the available information is not consistent. However, updated information claims that our microbiota is built up by some 40 trillion bacteria. The microbiota consists of 400-4000 different species, it weighs probably one kilogram and most of them are located in our gastrointestinal tract. The microbiota is often referred to as an organ in its own right.


We can’t live without our bacteria 

Historically, all we knew about bacteria was that they were causing infections and disease, that they were pathogens. Today we know that bacteria are generally beneficial and together with other microorganisms vital for our health. Just as we cannot live without air and water, we cannot live without our bacteria. One key function is to support the immune system and protect us from disease.

Our bacteria

  • Are our first line of defense against bad bacteria, pathogens
  • Support and educate our immune system
  • Help with digestion and absorption of nutrients
  • Produce certain vitamins, like vitamin B and K
  • May even affect our brain and thereby our mood


Good bacteria

Good bacteria can be found in food. Long before refrigerators and freezers, people used bacteria in fermentation to prolong the shelf-life of food. Examples of fermented foods are yoghurt, sauerkraut, and pickled vegetables. Common lactic acid bacteria used for fermentation are Lactobacillus acidophilus, Lactobacillus bulgaricus and Streptococcus thermophiles.

Truly healthy bacteria are known as probiotics. Probiotics are live bacteria that are proven to benefit our health by restoring the bacteria balance in the body and thereby have a positive effect on several health conditions. They are usually consumed as food supplements. Examples of common probiotic strains are Lactobacillus reuteri Protectis, Lactobacillus rhamnosus GG and Bifidobacterium animalis ssp. lactis BB-12.


Bad bacteria

A small percentage of all bacteria on earth are pathogenic, meaning they may cause health problems and disease. Food poisoning may be caused by E. coli and Salmonella, sepsis by S. aureus and S. pneumoniae can give pneumonia.

It is important to remember that bacteria of the same species but of different strains can behave completely different. Some species, like E. coli, harbor strains that are extremely pathogenic, like EHEC and ETEC, causing severe diarrhea. On the other hand, some strains ofƒ E. coli are commensals and they are one of the most common bacteria we carry in our gastrointestinal tract.