Introduction to Different Types of Microorganisms (Part Two)
In the previous article, two major types of microorganisms—viruses and bacteria—were discussed, along with their characteristics.
In this article, we will examine two additional groups of microorganisms: fungi and protozoa.
3. Fungi
Fungi are multicellular microorganisms that obtain the nutrients they need from warm, moist environments and from sources such as plants, food, and animals.
How Do Fungi Colonize the Human Body?
Fungi thrive in warm, damp environments, such as under rocks or between the toes. Unlike edible or poisonous mushrooms with their familiar umbrella-shaped appearance, fungi that live on human skin do not resemble mushrooms. However, all fungi produce spores, which continuously germinate and generate new spores. This method of reproduction allows fungi to spread easily.
Most fungi are harmless microorganisms. Those that grow on the skin often appear as rashes and are generally treatable. Although these skin infections usually do not cause serious harm, they can lead to intense itching.
Walking barefoot in places where fungi commonly grow—such as warm, humid locker rooms—can increase the risk of developing fungal skin infections. Many fungal diseases, including athlete’s foot and yeast infections, are not dangerous for healthy individuals. However, fungal infections can become severe or even life-threatening in people with weakened immune systems, such as those living with AIDS or cancer.
4. Protozoa
Like bacteria, protozoa are single-celled microorganisms, but they are generally larger and possess a nucleus and other cellular structures, making them more similar to plant and animal cells.
Although microscopic, protozoa are found in great numbers. Of the approximately 20,000 known species, many live in water, including lakes, oceans, rivers, and wetlands. If you examine a drop of water from one of these environments under a microscope, you may observe tiny protozoa moving with their whip-like tails (flagella).
Protozoa are beneficial in many ecosystems because they feed on bacteria and the remains of other organisms.
However, some protozoa are parasites that live inside other organisms, including humans. For example, the parasite that causes malaria enters the bloodstream through the bite of an infected Anopheles mosquito. Digestive illnesses caused by drinking contaminated water are another example of diseases resulting from parasitic protozoan infections.
Protozoa thrive in moist environments. As a result, intestinal infections and diseases such as amoebiasis and giardiasis are commonly transmitted through contaminated water.
As mentioned earlier, some protozoa are parasitic because they depend on other living organisms—such as animals or plants—for survival. For instance, the protozoan responsible for malaria grows inside red blood cells and eventually destroys them.
Some protozoa can also form cysts, which enable them to survive for long periods outside the human body and endure harsh environmental conditions.
