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  • Writer's pictureJsl Editorial Team



Microbes are tiny single-celled organisms that are not visible to the naked eye. They are also called micro-organisms or microscopic organisms. They live on soil, water, air, food and the intestines of animals, among other media. Microbes can survive in a wide range of temperature from extremely hot to intensely cold. They also need water to survive like all living things.


The types of microorganisms are bacteria, archaea, viruses, protozoa, microscopic fungi and yeasts, and microscopic algae.

  • Bacteria are unicellular organisms. Some bacteria need oxygen to survive and others do not. Some love the heat and others the cold environment. Well-known examples of bacteria include salmonella and staphylococcus bacteria. Bacteria has four different shapes - rod, spherical, spiral, curved.

Most bacteria aren't dangerous for humans. Many of them even live on or in our body and help us to stay healthy. For example, lactic acid bacteria in the bowel help us to break food down. Other bacteria help the immune system by fighting germs. There are those bacteria that also help us to produce certain types of food like yogurt or cheese.

Bacterial infections can be treated with antibiotics. These are medicines that kill the bacteria or at least stop them from multiplying.

  • Viruses have no cells of their own. A virus can't reproduce without a host cell because they're not living organisms. They're made up of some molecules surrounded by a protein shell. The genetic information found inside this shell is needed for the viruses to reproduce. Viruses invade healthy cells and start to multiply from these cells.

Many viruses are responsible for diseases. Some are harmless and only trigger a minor cold, while others can cause serious diseases like AIDS. Other diseases caused by viruses include influenza ("the flu"), measles or inflammation of the liver (viral hepatitis). Many other infections – including diarrhea or tonsillitis – can also be caused by bacteria, but viruses are usually responsible for them.

It's relatively difficult to fight viruses with medication. To protect against some viruses, we have to get vaccinated so that the body is better prepared to fight the virus. Importantly, we need to understand that antibiotics aren't effective against viruses.

  • Fungi are members of the Kingdom Fungi. It is a eukaryotic organism typically having chitin cell walls but no chlorophyll or plastids. Fungi may be unicellular or multicellular. They can live in lots of different environments. The best-known fungi include yeast, mold and edible fungi like mushrooms. Just like bacteria, some fungi occur naturally on the skin or in the body. But fungi can also cause diseases

Diseases caused by fungi are called mycoses. Common examples include ringworm, athlete’s foot or fungal infections of the nails. Fungal infections can sometimes cause inflammations of the lungs, or of mucous membranes in the mouth or on the reproductive organs, and also become life-threatening for people who have a weakened immune system.

  • Archaea are a domain of single-celled prokaryotic organisms. They were initially classified as bacteria with the name archaebacteria (in the Archaebacteria kingdom). However, archaeal cells have unique properties separating them from the other two domains, Bacteria and Eukaryotes. Archaea and bacteria are generally similar in size and shape, although a few archaea have very different shapes, such as the flat and square cells of Haloquadratum walsbyi.

Archaea are particularly good at withstanding extreme environments including the salt deposits on the shores of the Dead Sea. They are divided into four categories although the classification is difficult because most archea have not been isolated in a laboratory and have only been detected by their gene sequences in environmental samples. The four categories are: methanogens, halophiles, thermophiles, and psychrophiles.

Archaea are found living in association with eukaryotes. For example, methanogenic archaea are present in the digestive systems of some animals, including humans. Some archaea also live symbiotically with sponges.

a. Protozoa are the largest group of organisms on Earth based on numbers alone. They are either autotrophs or heterotrophs. Protozoa are unicellular organisms. Some are parasitic meaning they live in other plants and animals including humans, where they cause disease. For example, Plasmodium cause malaria.

Protozoa are motile and can move with the aid of cilia (tiny, outer, hair like structures that beat in a regular continuous pattern like flexible oars), flagella (long thread-like structures extending from the cell surface moving in a whip-like motion that produces waves that propel the microbe around) and amoeboid movement – (sending out pseudopodia which are temporary protrusions that fill with cytoplasm flowing from the body of the cell).

They come in many different shapes and sizes ranging from an Amoeba which can change its shape to Paramecium with its fixed shape and complex structure. They live in a wide range of moist habitats such as fresh water, marine environments and the soil.

a. Algae are members of a group of predominantly aquatic photosynthetic organisms of the kingdom Protista. They can be unicellular or multicellular. They gain energy through photosynthesis and are generally found in warm, wet areas. Algae do not have many of the distinct cell and tissue types, such as stomata, xylem and phloem, which are found in land plants neither do they have the phyllids (leaf-like structures) of bryophytes nor the rhizoids in nonvascular plants.

Algae include species ranging from unicellular microalgae, such as Prototheca, Chlorella and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to 50 metres (160 ft) in length. The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the Charophyta, a division of green algae which includes Spirogyra, stonewort and so on.

Algae are an important source of crude oil and food as well as a source of pharmaceutical and industrial products for humans. Additionally, they play useful ecological roles as oxygen producers and as the food base for almost all aquatic life.


A good deal of energy is expended in fighting or avoiding certain microbes for example, by using antibacterial soaps or taking antibiotics to fight infection. However, research has helped us to identify quite a number of microbes that are beneficial to human beings and their applications in different fields of human endeavours as stated below:

  • Science: Microbes are generally used industrially for the production of antibiotics, vaccines and insulin. As well as to make the diagnosis of certain diseases.

  • Microflora: These are bacteria that are found naturally in the digestive tract of humans where they are responsible for breaking down food remains. The microflora is also responsible for defending the body from fungi and bacteria that are harmful to human health. Additionally, it produces vitamin K which is necessary to regulate blood clotting processes.

The Beneficial bacteria Which live in our gut are known as probiotics and can be obtained commercially when the body fails to preserve them.

  • Biotechnology: this is the branch of science that deals with the manipulation of living organisms through genetic engineering. It depends directly on microbes.

Microbial biotechnology is responsible for the study of genomes, which allows an improvement of vaccines and development of better tools for the diagnosis of diseases.

Progresses made in microbial biotechnology have allowed the control of animals and plants pests by the development of agents that catalyze pathogens and fermentation organisms. This has also allowed the bioreparation of soils and water polluted chiefly by the agricultural processes.

In general, microbes, together with biotechnology, have allowed the development of alternative energy sources, Biofuels, Bioalcohol and research for the field of agriculture.

  • Waste treatment: Microbes are responsible for breaking down matter by raising its temperature and producing carbon dioxide. In this way, a substance called humus with a similar appearance to the soil is generated.

Microbes are able to clean both industrial and domestic waste through a biological process of decomposition or stabilization of organic matter known as composting. Fungi, bacteria and protozoa are responsible for the production of anaerobic compost.

Aquaria and ponds can be filtered using algae to absorb nutrients from the water in a device called an algae scrubber also known as an algae turf scrubber.

Additionally, sewage can be treated with algae. This reduces the use of large amounts of toxic chemicals that are otherwise used.

  • Food Industry: Microbes are used in the production of fermented foods and beverages. The fermentation process leads to the production of alcoholic beverages or acid based dairy products and it occurs when microorganisms get energy from food cells without having to take oxygen. Yoghurt, cheese, olives, sausages, chocolate, bread, wine, beer and soy sauce are foods with the help of different types of bacteria and yeasts.

  • Agriculture: The microbes that live in the soil help to improve agricultural productivity by allowing plants to absorb more nutrients as energy sources needed to live. The plants then yield their waste to the microbes so that they feed on them and generate biofertilizers. Humans naturally use these microbes to develop fertilizers and biopesticides. In this way, plant foods can be grown in a controlled and safe manner, blocking potential threats to the environment and contributing to the acceleration of natural processes such as the release of nitrogen from the soil.

Algae can also be used to capture fertilizer runoff from farms. When subsequently harvested, the enriched algae can be used as fertilizer.

  • Air: Air Is composed mainly of gases, dust particles and water vapor. Furthermore, it also contains microorganisms in the form of vegetative cells, spores, fungi, algae, viruses and protozoan cysts.

Microbes cannot grow in air but, it transports them along with the particulate material. However, the number of microbes in the air is considerably lower than can be found on land or water. Microbes in the air are responsible for the breakdown of dead cells that are released from the skin of humans. If these microorganisms did not exist, the world would be filled up with a large mass of dead skin.

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