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Monday, 3 December 2018

Microorganisms; the good, the bad and the ugly

Microorganisms are very small organism that are not visible to the naked eyes. They, although very tiny, are everywhere and have large effects on their environment and other organisms. Are all microbes bad? What are some popular microbes and their importance? Read this article to know some good microbes, bad microbes and other notable microbes.

Microbes 101. Introduction to the tiny world

Microorganisms aren't aliens or so different from we humans or other organisms we can see. Here are a few notes about microbes:
  • They're just simpler and tiny organisms. 
  • Most of them are unicellular (meaning they have just 1 cell) but some are multicellular (meaning they're made up of two or more cells)
  • They can be found in all kingdoms: Monera (Bacteria), Protista (Unicellular animal-like and plant-like organisms), Fungi, Plantae and Animalia.
  • Some can live individually while others form colonies (making them visible)
  • Some are free living while others depend on other organisms for survival

Of course the list is endless but let's focus on classifying microbes based on their benefits or harms.

The good; microbes we benefit from


These microbes are plant-like protists. They're Unicellular and like plants, they're able to manufacture their food through photosynthesis. They can be found everywhere especially in water bodies. Here are a few ways we benefit from them:
  • They're responsible for the production of about 20% of the Earth's oxygen each year (they release oxygen through photosynthesis)
  • Since they're very small, they're in the bottom of the aquatic food chain. Other organisms like juvenile (young) shrimps, octopuses and fishes eat them, larger aquatic organisms eat these juveniles, subsequently, it gets to the top of the food chain (man).
  • Since they number in trillions and float in water bodies, they form a blockage for sunlight (one reason why the ocean waters aren't clear) so that heat (which travels with sunlight) cannot penetrate deep into the ocean. Since water is around 70% of the Earth's surface, the role of diatoms in maintaining the temperature of the oceans affects us on land as well.

The niche (role) of diatoms in the environment cannot be overemphasized.


There are different Penicillium species. These organisms under kingdom Fungi have been a breakthrough for man. They can be found in temperate regions and can also be found in damp parts of buildings. They produce a substance that stops the growth and reproduction of some bacteria like Staphylococcus. This substance which they produce, is what we call penicillin today. The discovery of penicillin started the study and production of antibiotics. If not for these organisms, who knows, a lot of people would have died because of incurable bacteria infections. You see? Microbes have medical importance as well


These are under the kingdom Eubacteria (Monera). They can be found in the soil as either free living or in association with plants. They (when in the root of legumes) can collect nitrogen gas (N2) from the atmosphere, convert it into a simpler form of nitrogen then send it to the plant (which the plant needs for growth). Legumes like beans, peas, clover, etc. Rhizobia are especially important in the mass cultivation of such plants in places where fertilizers (to supply nitrogen to the plant) aren't available or affordable. This relationship with legumes have proven the agricultural importance of microbes.
Rhizobia in the root of a legume

Microbes that are beneficial to man and the environment are so much and we're grateful. Some like the Lactobacillus aid in the fermentation of milk and also breaking down of food particles during digestion. Their benefits cannot be overemphasized.

The bad; microbes that harm us

Clostridium tetani

It is a bacteria. It is found mostly in soils worldwide. It can be free living and is very deadly when it is parasitic. It is responsible for Tetanus. Tetanus is a severe disease that children worldwide are being vaccinated against it. Its spores (reproductive part) enter our body through wounds and release toxins that cause the diseases. This bacteria is the reason why children are still vaccinated till today. It is advised that you get vaccinated if you have an injury around the lower region of your body to prevent tetanus.


Plasmodium is a protozoa (animal-like Protista) that infects the blood of different vertebrate animals (including man) to form the malaria disease. There are different plasmodium species like P. malariae, P. ovale and P. falciparum. There is also a zoonotic species (able to infect different species) called the P. knowlesi. Plasmodium can be found in places with high humidity, temperature and rainfall. Its disease Malaria is responsible for the death over 1 million people per year especially children (according to UNICEF). Plasmodium enters into our bloodstream through infected mosquitoes. Mosquitoes breed and the young grows in stagnant water, plasmodium infects some mosquitoes through that medium and enters into our bloodstream when the mosquitoes penetrate into our skin.


Molds or moulds (under Fungi) are filamentous fungi (i.e they grow in filamentous colonies therefore appearing as multicellular as opposed to Unicellular yeast that grows independently). Mold is a diverse term used to refer to different species of fungi. They are decomposers (meaning they breakdown food into simpler nutrients). They are responsible for most food spoilage. They produce little spores that the wind carries so whenever you expose your food for long, the spores germinate and begin to form molds. Fungi, unlike plants, don't produce their food through sunlight so they rely on your food and other sources for nutrient. When molds are available in large quantity, they may cause serious health problems like allergies and other respiratory problems.
Image result for mold
Mold decomposing an orange

Other notable microbes


This is kingdom Protista. It exhibits both plant-like and animal-like features. Like plants, it is able to produce it's own food through photosynthesis (in the presence of sunlight). When there is no sunlight, it feeds on green algae and other protists. Euglena can be found anywhere there is  green algae (ponds, water puddle, stagnant water, etc). The ability of Euglena to generate energy like plants (autotrophic) and animals (heterotrophic) makes it notable and special.


This is a plant-like bacteria. The difference between Protista and Bacteria is that protists are eukaryotes (having nucleus) while Bacteria are prokaryotes (having no nucleus). Cyanobacteria, although being a bacteria, is the only prokaryote that is able to carry out photosynthesis. Cool right? Some Cyanobacteria also fixes nitrogen from there atmosphere to become available to plants (just like Rhizobia). They're indeed notable for been the only prokaryotic autotrophs.


Tardigrades or water bears are under kingdom Animalia. They're Unicellular and can be found literally everywhere on the Earth. What makes them notable is their nature of endurance. These organisms can exist in the hottest, coldest and most actively radioactive places on Earth, they can also survive in space. They can survive after being dehydrated and they can reduce their metabolism to below 0.01% of how it should work. Although, they don't prefer to live in such extreme conditions, their ability to endure makes them notable.
A tardigrade (water bear) under an electron microscope

Reading this article, you must've realized that microbes are everywhere. Some benefit you, some harm you and you're unaffected by others. What's your favorite microbe? 

S.O. Nzeako, F.O. Nduka, C.N. Eze (2018). Biology of lower Invertebrates. (1):14-17