In which environments do bacteria live


Origin of Life

The earth around four billion years ago: violent volcanic eruptions, meteorite impacts and lightning strike the scenery. The enormous heat and radioactive radiation drive chemical reactions. It thunders and crashes.

The first chemical compounds emerge from sulfur and hydrogen. Larger molecules are also formed. Amino acids and fats are added later.

The original soup simmers as if in a saucepan. The first long-chain molecules enclose free amino acids - prototypes of a cell.

It will take a while before the work in these inclusions is coordinated like in a factory. Simple bacteria emerged 3.5 billion years ago. They live between fire and ashes.

During the next three billion years the earth cools down, water vapor is created and oxygen is released. The scene calms down. A variety of cells has emerged.

The first higher cell structures must have formed from these original forms of life around 500 million years ago. Hard to imagine that the tiny ones create the breeding ground for everything else such as plants, animals and humans.

This is how scientists imagine the origin of life on this planet. But they have not yet understood all the processes.

Probably some of them will never be fully clarified because hardly all conditions of the primordial earth can be simulated in the laboratory.

It is assumed, however, that cells with a real nucleus (eukaryotes) and bacteria (prokaryotes) developed from common ancestors. How exactly, at what time and in what relationship to each other this should have happened, is not known.

Archaea and Bacteria

It was towards the end of the 1970s when some researchers came out with a sensation: They had found new life on our planet - in boiling sulfur springs.

What nobody could have imagined was actually possible: Tiny bacteria cook in acrid sulfur vapor that only feel at home at 100 degrees Celsius.

Because of their preference for archaic locations that resemble the living conditions of the primordial earth, science today calls these artists of life archaebacteria (also archaea).

The "riding primeval dwarf" Nanoarchaeum equitans is such an archaebacterium. It probably comes from the prehistoric times of life and, with its 400 nanometers (0.4 thousandths of a millimeter), is considered the smallest living creature on earth.

It was discovered off Iceland by the German researcher Professor Karl Stetter.

The "dwarf" only grows in boiling water and likes to be misted by volcanic fumes - and he always "rides" on another archaebacterium called "fireball" (Ignicoccus).

Little by little, the scientists unearthed more and more such strange organisms.

In the course of research it has been found that archaea differ significantly from conventional bacteria. Therefore, a distinction is made between archaea and the classic bacteria, which are also known as eubacteria.

In the family tree of life, both lines of development probably branch off from one another very early on.

Even if both groups are summarized under the term "prokaryotes" - their metabolism and life forms differ greatly from one another. Most archaea operate their metabolism with sulfur and / or hydrogen. For many people, oxygen is a cell poison.

Research with obstacles

The difficulty in researching these bon vivants lies in their preference for extreme locations. The heat-loving ones among them threaten to freeze to death at 80 degrees Celsius.

Others prefer high salt concentrations or extremely acidic environments. Only when the laboratory resembles a seething witch's kitchen does it become cozy for these little ones.

With the progress of evolution, archaea have also opened up less hot locations. One of them is our body - from a bacterial point of view, a wonderful playground with many macro and micro biotopes: the finest cracks in the skin, a huge, oxygen-poor intestine with countless invaginations and villi or the mouth with numerous depressions and bulges.

On our teeth, under the protective film of larger eubacteria, archaea hide from deadly oxygen and happily produce the biogas that is responsible for the unpleasant phenomenon that some fellow citizens struggle with: bad breath - caused by methane.

Archaea can even be found far down in the sea, at so-called black smokers; where the mineral-rich water almost reaches the boiling point.

They grow under the ice in Alaska 4000 meters deep in the earth - where it gets hotter again towards the earth's core.

It is precisely this finding that leads some researchers to suspect that bacteria can also exist on Mars. Its surface is icy cold while the core of the planet gets scorching hot.

Peaceful archaea

There are no known representatives of the archaea that could cause disease. Infections originate exclusively from the classic bacteria; these include plague, gonorrhea, cholera, syphilis, diphtheria, typhus, tuberculosis and borreliosis.

While most of the bacterial pathogens are currently known and, for the most part, also unmasked, the determination beyond medicine is progressing very slowly: Researchers estimate that not even five percent of all bacteria on our planet have been discovered so far.

Ecological importance

The ecological benefits of the archaea have become more and more important since their discovery. They had first been isolated from volcanic areas, then from the ocean floor, and finally from habitats with high salinity such as the Dead Sea.

In the meantime their existence has also been proven in humans. Today it is assumed that archaea are the engine of the earth's material cycle. They probably play a crucial role in the sulfur and nitrogen cycle.

The classic eubacteria are both a blessing and a curse. They take on the degradation and recycling of materials and feed organic substances such as carbohydrates and inorganic compounds back into the natural cycle.

Some bacteria bind free nitrogen and thus enrich the soil for plant growth. They are mainly found on the roots of pea family plants such as clover, beans, peas and lentils.

All bacteria together break down tons of recyclable material and thus create the breeding ground for our existence.

Without them, the earth would be ten meters high littered with corpses - that's how drastically many scientists today formulate their ecological significance.