Meaning of Microorganism

What is Microorganism :

A microorganism or microbe is a living being or organism so tiny that it can only be seen through a microscope.

The word microorganism is formed from the union of the Greek term microphone, meaning ‘small’ or ‘tiny’; the Latin term organummeaning ‘tool’, ‘instrument’, and the suffix –ism, which means ‘system’. In turn, its synonym microbe includes the Greek root biowhich means ‘life’.

Characteristics of microorganisms

  • Microorganisms require water to metabolize.
  • Metabolic processes are usually very intense and fast.
  • They have a high capacity for reproduction.
  • They generate important changes in the environment where they stay.
  • The air is one of its propagation vehicles.

Types of microorganisms


There is a great diversity of microorganisms, both in shape and size. In fact, biodiversity is so extensive that, very probably, not all the microorganisms that exist both on Earth and in space are still known.

Microorganisms are unicellular by definition. They are essential for the development of life, since they participate in the bio-geo-chemical cycles that occur in nature.

In fact, many bacteria are necessary for the proper functioning of the body. Some of these are: lactobacilli, Tobacillus acidophilus, Streptococcus faecium, Escherichia coli and bifidobacteria.

prokaryotic microorganisms

Prokaryotic microorganisms are those that do not have a nucleus. Among them we can mention the archaea and the bacteria. These are the most widespread microorganisms in nature.

You may be interested:  Gold

Bacteria can be spherical (cocci), rod (bacilli), curved (vibrios), or spiral (spirilla). They play an important role in nature, by participating in different processes. For examplethe degradation of matter.

See also Archaea.

eukaryotic microorganisms

They are all those that contain nucleus and organelles. They are divided into protoctists (where they are counted algae Y protozoa), and in mushrooms.

Protoctist or protist microorganisms are not capable of forming any tissue. They are very diverse from each other, which makes it difficult to find common characteristics among them.

Fungi encompass a wide spectrum of species. Among them, some are microscopic in size, such as yeasts and mold spores. Of the yeasts depends, for example, the processes of fermentation.

See also eukaryotic cell.

Pathogenic microorganisms

Pathogenic microorganisms are those microorganisms that enter a healthy organism and invade, colonize or infect it, causing different types of diseases. Among them we can count bacteria, viruses, fungi, protozoa and prions.


Certain types of bacteria can be harmful to health, since they invade the body and release toxins that deteriorate it. The most common types are cocci, spirilla, and bacilli. Among some harmful bacteria, we can mention the following examples:

  • Streptococcus pneumoniae, which causes minor infections such as minor infections such as acute otitis media and sinusitis. It also causes other serious diseases such as pneumonia, septicemia, fever without source, meningitis, among others.
  • Salmonellaresponsible for salmonellosis.
  • Yersinia pestis, which causes a serious infection called plague.
  • Acinetobacter baumanniiwhich causes serious infections in the lungs, brain, and blood.
You may be interested:  Dynamic

See also Bacteria.


Some fungi are capable of producing skin infections as well as mucous membranes. For example,

  • Candida albicansresponsible for candidiasis;
  • Trichophytonwhich causes ringworm or respiratory illnesses caused by airborne mold spores.

See also Kingdom fungi.


Protozoa or protozoa are eukaryotic unicellular organisms that are characterized by being mobilized by flagella, pseudopods or cilia, and by being predators. For example,

  • Trypanosoma cruzicausing Chagas disease,
  • Plasmodium falciparum that causes malaria and
  • Entamoeba histolytica that causes amebiasis.

Viruses and prions

Many researchers dispute whether or not to consider viruses microorganisms. This is because, in order to reproduce and feed, viruses need a host cell, to which they must inoculate their genetic content. This inability to live and reproduce by themselves (parasitic character), makes viruses as living beings questioned.

A similar controversy has been generated around prions, which many scientists discard from the list of microorganisms.

In any case, viruses modify the metabolism of cells to live in them, so that they cause diseases. Among them we can mention the acquired immunodeficiency virus (HIV), the hepatitis virus and the virus H1N1known as swine flu.

Prions, meanwhile, are infectious agents made up of a protein known as prion. They lodge in tissues and destroy cells, particularly neurons. They are associated with the disease popularly known as “mad cow disease”.

See also Viruses.