The bacteria they are living beings unicellular and they are prokaryotic organisms. This means that its genetic material, a double-stranded circular DNA molecule, is free in the cytoplasm, not enclosed within a nucleus. For example: Escherichia coli, Bacillus thuringiensis, Clostridium botulinum.
Since microfossils and stromatolites (fossil colonies of bacteria mixed with minerals) have been found in sediments from various geological eras, and even in sedimentary rocks older than 3.5 billion years, it is claimed that bacteria have existed since very ancient times.
So much so that they have existed for a long period of Earth’s history in which there were not even other forms of life. In fact, bacteria introduced very significant evolutionary events.
Types of bacteria
It is usually distinguished today into two large groups:
- The bacteria. They are represented by those that predominate in today’s natural environment, with the presence of different levels of oxygen and varied metabolisms.
- The Archaea. Evolutionarily they represent a previous category, with metabolisms specially adapted to extreme environmental situations, such as the lack of oxygen (remember that, according to rigorous studies, there was no oxygen on the planet until vegetables, the great oxygen liberators, appeared), or environments very saline or very acidic and with high temperatures.
The great evolutionary success of bacteria is largely attributed to their surprising metabolic versatility. It can be affirmed that all the possible mechanisms for obtaining matter and energy exist distributed in the various classes of bacteria.
Examples of bacteria
| Escherichia coli | Bacillus thuringiensis |
| Bacillus subtilis | Clostridium botulinum |
| Mycobacterium tuberculosis | Clostridium tetani |
| Nitrobacter winogradsky | Pseudomonas aeruginosa |
| Thiobacillus ferooxidans | Falvobacterium aquatile |
| Rodospirillum rubrum | Azotobacter chroococcum |
| Chloroflexus aurantiacus | Neisseria gonorrhaea |
| Enterobacter aerogenes | Haemophilus influenza |
| Serratia marcescens | Yersinia enterocolitica |
| Salmonella typhi | Staphylococcus aureus |
Importance of bacteria
Bacteria are extremely important in nature, as they are present in natural cycles of the most important elements for life: nitrogen, carbon, phosphorus, sulfur, etc.
They can transform organic into inorganic substances and vice versa. While many bacteria are pathogenic and cause disease in plants and animals (including humans).
Many others are used in various industrial processes, such as food processing and alcoholic drinks, drugs, antibiotics, etc.
Bacteria characteristics
Bacteria are microscopic and outside the membrane that encloses their cytoplasm there is a structure called cellular wall. More externally still, some bacteria form a jelly-like structure called capsule.
Bacteria reproduce by Binary fission and very quickly, so that they are very abundant. Due to their highly varied metabolism, they can thrive in countless environments such as:
- Sweet and salty waters
- Organic material
- I usually
- Fruits and grains
- Plants
- Animals, both inside and on their surfaces
Many bacteria group together forming pairs, chains or bundles; they are often mobile; the flagellum (a species with a long appendage) is the structure that usually contributes to motility, but not the only one. The set of bacteria in culture is called a colony.