There are five types of microorganisms; bacteria, fungi, protozoa, algae and viruses. Bacteria are one-celled organism. They are named according to their shapes. Coccus is a spherical-shaped bacterium, bacillus is a rod-shapedbacterium and spirilium is a wavy-shaped bacterium. Another feature of bacteria is that they have a long slender flagellum. Bacteria can form spores when they are in unfavorable conditions. These spores can withstand heat and dry conditions. Thus, they can persist for a long time.
Fungi look like plants, but they do not have chloroplast. Therefore, they cannot synthesize their own food. There are varieties of sizes of fungi. Basically, they are made up of growing structures called mycelium and they produced reproductive bodies called spores. Examples of fungi are mucor, penicillium, yeast and mushroom.
Viruses are unique in the sense that they can only be considered as living when they have entered living things. When they are not in the living things body they are in a crystalline form. Due to this nature, they can exist for a long time even though the environment is not favourable.
Microorganisms are living things. Thus, they undergo life processes such as breathe, grow and move. The life processes they undergo are similar to plants and animals but in a simpler way. For example, they do not need special organs for breathing. They do not even involve complex mechanism when moving.