The word bacterium comes from a Greek term that means “walking stick”. It’s about a prokaryotic unicellular microorganism what can cause diseases, fermentations or putrefaction in living beings or organic matter.
Because they are prokaryotic cells, they lack a nucleus or internal organelles. On the other hand, although the term comes from rod, bacteria can be shaped like bar, sphere or propeller.
Bacteria can be classified into various groups based on different criteria. Thus, for example, if we start from what its form is, we find the fact that there are four clearly delimited types:
Bacilli They are the bacteria that are defined by being elongated and because they have the possibility of being curved or straight. In the same way, it is necessary to underline the fact that they may or may not have flagella.
Leptothrix. Large are those that are framed under this name and have as their main hallmark that they can present filaments called septates.
Spirilos. In this case, this category includes bacteria that have a helical curved appearance.
Coconuts. The bacteria that receive this name are those that have a rounded shape and have the possibility that they can appear singly, in pairs or in the form of a clustered chain.
In addition to all the above, we also have to underline the fact that bacteria can also be classified based on what their respiration is. In this case, we could make two large groups: aerobic, which are those that make use of oxygen, and anaerobic, which do not use oxygen but other elements such as carbonate, for example.
Thirdly, we can determine that bacteria can be classified equally taking into account their need for growth. This fact would lead to finding two types of bacteria: heterotrophs (parasitic, putrefactive, symbiotic …) and autotrophs (photosynthesizing, chemosynthesizing …).
Bacteria can live in any habitat; some species even survive in outer space. These characteristics make bacteria the most abundant organism in the world: 40 million bacterial cells can coexist in just one gram of Earth.
The human body harbors about ten bacterial cells for every human cell. The immune system allows most bacteria to be harmless or even beneficial (they aid digestion, for example). However, certain bacteria can cause serious illnesses such as tuberculosis, the leprosy and the anger.
Bacteria help in the production of cheese, butter, and yogurt, play important roles in the manufacture of certain drugs, and help treat wastewater. They are also used for leather tanning and tobacco curing.
The discipline responsible for the study of bacteria is known as bacteriology. It is a branch of the microbiology, the science dedicated to studying microorganisms. Bacteriology and microbiology belong to the field of biology.
These scientific fields have advanced thanks to technological advances, although it is estimated that we know only 1% of the microbes in the biosphere.