Microorganisms are so small that they cannot be seen with the naked eye; they can be seen only with the help of a microscope. Therefore they are also known as microbes, and the science that deals with their study is microbiology. They are found everywhere – in air, water (ponds, lakes, rivers and oceans), soil and even inside our bodies. They remain inactive under unfavourable conditions and become active during favourable conditions.
1. Five Categories of Microorganisms
Microorganisms are studied under five categories: virus, bacteria, fungi, algae and protozoa.
| Group | Study is called | Kingdom |
|---|---|---|
| Virus | Virology | – |
| Bacteria | Bacteriology | Monera |
| Fungi | Mycology | Fungi |
| Algae | Algology (phycology) | – |
| Protozoa | Protozoology | Protista |