Microorganism – Concept, types, characteristics and examples

We explain what a microorganism is, its characteristics and classification. In addition, beneficial and harmful microorganisms.

Microorganism - microbe
Microorganisms exist in numerous varieties, of different shapes and sizes.

What is a microorganism?

Microorganisms are those organisms that, due to their small size, they are imperceptible to the eye.

Also called “microbes,” these organisms have a very basic biological organization: a significant proportion of them have only a single cell. In addition, they are characterized by numerous varieties, of different shapes and sizes.

Prokaryotic and eukaryotic single-celled organisms, along with certain fungi and algae make up the universe of microbes.

Characteristics of microorganisms

Microorganisms - microbes
Microorganisms have the ability to alter the environment in which they are found.

Microorganisms have a number of characteristics in common:

  • Their size is so small that they are imperceptible to the naked eye.
  • Its metabolic reactions are very fast.
  • Their relationship with the environment is intense.
  • They need water to metabolize.
  • They develop dispersal and resistance mechanisms.
  • They have the ability to alter the environment in which they are.
  • They reproduce at great speed.
  • Its activity is essential for life on the planet.
  • They are part of the biogeochemical cycles that take place in nature.
  • They are very light, so they are transported in the air.

Types of microorganisms

Within nature, different types of microorganisms can be identified. Some of them are the following:

  • Virus. They are the most basic microbes and can only be seen with electron microscopes. To reproduce, they must infect other unicellular organisms, which are inoculated with their genetic content (they can only reproduce in a host cell).
  • Cyanophytic algae. They are large bacteria and are characterized by photosynthesis in a way very similar to plants, that is, oxygenic (they give off oxygen).
  • Mushrooms. Like yeast, many of the organisms that make up the Fungi Kingdom are microscopic.
  • Protists. These are large volume eukaryotic single-celled microbes. In general, they develop in aquatic environments, which can be fresh or salt water, or in very humid places. Although some varieties develop parasitic lives, in general, these organisms prey on other microorganisms when it comes to feeding.
  • Arch bones and bacteria. They are two types of prokaryotic and single-celled organisms, and they are the simplest microbes. They make up the group of microbes with the greatest presence on Earth, they feed on the habitat in which they are found and their reproduction is from the division of their genetic material.

Harmful and beneficial microorganisms

Microbes - microorganisms
Viruses can only reproduce within a host cell.

There are microorganisms that are harmful to people’s health, because by attacking vital cells, they can cause diseases that, on some occasions, can lead to death. Some of these microbes are:

  • Bacteria They are microorganisms that belong to the Monera Kingdom, they release toxins and can survive inside or outside a cell. In addition, they are unicellular and lack a nucleus. Not all bacteria are pathogenic, but some can be beneficial to health or neutral.
  • Virus. These microbes, which are spiral or spherical in shape, can only reproduce within a host cell. These microbes, which can be infectious, have only one type of nucleic acid, and are always pathogenic. Viruses can never be killed with antibiotics and only their symptoms can be attacked.
  • Mushrooms. These microbes can cause infectious diseases and grow outside of bodies.

Within the microorganisms there are also varieties that are beneficial for life, the environment and human health. Here are some examples where microbes are beneficial:

  • Food industry. Microbes play a fundamental role in the production of certain products. For example, yogurt, cheese or beer are the result of fermented foods, thanks to the action of microbes. In these cases, the microbes produce lactic acid that facilitates the preservation of food.
  • Body. There are microorganisms that participate in certain processes within the human body, such as digestion and even act in defense of other organisms that can affect health.
  • Trash. Through certain biological processes such as stabilization or decomposition, the microbes clean up the waste. They end up turning the waste into humus or compost.
  • Farming. Many of the microorganisms that inhabit the soil facilitate agricultural production. Either because they act as pesticides or because they help plant growth.

Examples of microorganisms

Escherichia coli - microorganisms - microbes
Escherichia coli microbes live in the intestines.

Some of the best known and studied microorganisms, which can cause disease, are the following:

  • Escherichia coli. They are the microbes that cause diseases such as bloody diarrhea or kidney failure. They live in the intestines.
  • Salmonella. These microorganisms cause various diseases. A good part of them are diarrheal. It is spread through urine and feces.
  • Streptococcus pneumoniae. They are the microbes that cause diseases such as pneumonia, sinusitis or otitis, as well as meningitis.
  • Mycobacterium tuberculosis. In general, they affect the functioning of the liver and lung, but they have the ability to make any organ of the body sick. They are very resistant to cold microbes.
  • Yersinia pestis. This microbe, which can cause plague, lives in rodents, although it is transmitted through fleas.
  • Bacillus cereus. This microorganism causes poisoning, vomiting, diarrhea and nausea. It lives in food and is characterized by reproducing very easily.
  • Treponema pallidum. This microorganism is fought with penicillin and is characterized by not surviving outside the body. Also, this germ causes the sexually transmitted disease syphilis.