When you hear the word bacteria, you automatically think of feverish illnesses, suppurated wounds or nasty gastrointestinal infections. But not all bacteria are dangerous to us – on the contrary, many types of bacteria protect us from their nasty relatives, help us with our immune defenses or produce important vitamins. Bacteria are small organisms that consist of only one cell and whose genetic material, unlike that of humans, is not located in a cell nucleus but floats freely around in the cell. Bacteria reproduce by simply dividing the cell, and some of them can change shape and survive as spores for many years despite unfavorable conditions.
Bacterial species
It is believed that more than 90 percent of all bacterial species are still unexplored, although more than 10,000 bacteria have been accurately described and studied in the last three hundred years. Bacteria are classified into highly scientific categories according to certain characteristics – but in addition there is a simple classification according to their external shape: Spherical bacteria are called cocci, and rod-shaped ones are called rods.
The relationship between bacteria and humans
A bacterium, depending on whether it is a “friend” or “foe” of humans, can be classified as a
- Symbiont
- Commensal
- Parasite
denote.
A symbiotic relationship exists when both the human and the bacterium derive a benefit from the presence of the other. This benefit can be, for example, that one organism provides nutrients for the other and is defended from enemies in return.
When an organism such as a human being has neither benefit nor disadvantage from the presence of a bacterium, but the bacterium feeds at its expense, e.g., on food that cannot be used or waste produced during digestion, the bacterium is called a commensal. Many bacteria that live on or in us are symbionts or commensals and form the normal bacterial flora of the skin, oral mucosa, intestine or vagina.
Parasites are living organisms that require another organism to survive – its presence triggers disease. In addition to bacteria, worms, fungi and many other life forms are parasites of humans and are responsible for diseases.
Where do bacteria make themselves useful?
Bacteria play an important role in many areas. In the oceans, together with algae, they form the plankton, and in the soil they are involved in the production of plant nutrients.
Bacteria are used by humans in the purification of wastewater and the decomposition of waste. Biotechnical methods are used to produce antibiotics and enzymes with the help of some species, 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, perform important functions in immune defense and in nutrient supply.
Certain bacteria are added to foods or medicines to improve intestinal flora, treat certain intestinal diseases, and prevent allergies or neurodermatitis.
