Bacteria - not every germ makes you ill

When one hears the word bacteria, one automatically thinks of feverish diseases, ulcerated wounds or nasty gastrointestinal infections. But not all bacteria are dangerous for us - on the contrary: Many types of bacteria protect us from their evil relatives, help us with the immune system or produce important vitamins. Bacteria are small creatures that consist of only one cell and whose genetic material, unlike humans, is not located in a cell nucleus, but floats freely in the cell. Bacteria multiply by simply dividing the cell, some of them can change their shape and survive many years as spores despite unfavorable conditions.

bacterial species

It is estimated that over 90 percent of all bacterial species are still unexplored, even though over 10, 000 bacteria have been accurately described and researched in the last three hundred years. Bacteria are classified according to specific characteristics into highly scientific categories - but besides there is a simple classification according to their external form: spherical bacteria are called cocci, rod-shaped ones are called rods.

The relationship between bacteria and humans

A bacterium can be thought of as a "friend" or "enemy" of humans

  • symbiont
  • commensal
  • parasite


A symbiotic relationship exists when both, humans and bacteria, benefit from the presence of the other. This benefit can be, for example, that one organism provides nutrients for the other and is defended against enemies.

If an organism such as humans has neither the advantages nor the disadvantages of the existence of a bacterium but feeds at its own expense, for example, from unprofitable food or waste arising from digestion, the bacterium is called commensal. Many bacteria that live on or within us are symbionts or commensals and form the normal bacterial flora of the skin, oral mucosa, intestine or vagina.

Parasites are living things that need another organism to survive - its presence triggers disease. In addition to bacteria, worms, fungi and many other life forms are parasites of humans and responsible for diseases.

Where do bacteria make themselves useful?

Bacteria play an important role in many areas. In the oceans they form the plankton together with the algae, in the soil they are involved in the production of plant nutrients.

Man uses bacteria to clean wastewater and decompose waste. Biotechnical methods are used to produce antibiotics and enzymes with the help of a few types, so bacteria also have a firm place in biotechnology and genetic engineering.

Bacteria live as symbionts and commensals on and in humans and as bacterial flora take over important functions of the immune defense and in the nutrient supply.

In foods or medicines certain bacteria are added to improve the intestinal flora, to treat certain intestinal diseases and to prevent allergies or atopic dermatitis.

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