Microorganisms

World of Microorganisms

1.1

World of Microorganisms

1. Classification of microorganisms

Bacteria
Fungi
Protozoa
Virus
Algae

2.

	Bacteria	Fungi	Protozoa	Virus	Algae
Size	0.2 µm - 10 µm	10 µm - 100 µm	5 µm - 250 µm	0.02 µm - 0.4 µm	1 µm - 100 µm
Shape	Coccus, bacillus, spirilla, vibrio	Spherical, filamentous	Spherical, spindle-shaped, irregular shaped	Sphetica;, helix, polyhedral, complex	Spherical, oval-shaped, filamentous
Nutrition	Autotrophic, saprophytic, parasitic	Saprophytes, parasitic	Saprophytic, parasitic	-	Autotrophic
Habitat	Air, water, soil, food, bodies of other organisms	Places with decaying matter, faeces, animal skin and food	Aquatic habitats, damp place, bodies of living organisms	Live in living host cells, form crystals outside a living cell	Aquatic habitats, damp place
Method of reproduction	Asexual: binary fission Sexual: conjugation	Asexual: budding, spore formation Sexual: conjugation	Asexual: binary fission Sexual: conjugation	-	Asexual: binary fission, spore formation Sexual: conjugation
Example	Bacillus sp., Vibro sp.	Mushroom, yeast	Paramecium sp., Ameoba sp.	Influenza A virus	Chlamydomonus sp. Spirogyra sp.

3. Factors that affect the growth of microorganisms

Factors	Explaination
Humidity	Damp conditions promote the growth and reproduction of microorganisms. In dry condition, some bacteria will form cyst or spores.
Light	Microorganisms with chlorophyll prefer light condition. Fungi and few bacteria prefer dark condition. Exposure to UV light can kill microorganisms.
Temperature	Most microorganisms prefer 35 °C - 40 °C. Low temperature in refrigerator reduce growth rate of microorganisms. High temperature can kill microorganisms.
pH value	Optimum pH for most microorganisms is pH 7. Some microorganism can live in environment with slightly acidic or alkaline.
Nutrients	The growth rate of microorganisms depends on amount of nutrients.