Microbiology is the study of microorganisms. These are tiny living organisms such as bacteria, viruses, fungi and protoctista which are usually too small to see with the nake eye
To see and understand them properly you need to use a Microscope. There are many reasons that we investigate microorganisms; They play a vital role in the decay and the recycling of nutrients in the environment, they can cause disease and they are very useful to people.
Many microorganisms can be grown in the lab. This allows us to learn a lot about them. We can find out which nutrients they need to survive and which chemicals kill them. We can also discover which microbes can br useful to us, or cause deadly disease.
If you want to find out more about microorganisms you need to Culture them. In other words, grow very large numbers of them so you can see the colony as a whole.
To culture them you must provide them with everything they need. This usually means providing a culture medium containing carbohydrate to act as an energy source. Along with this, various mineral ions and in some cases extra, supplementry protein and vitamins are included.
The nutrients are often contained in an agar medium. Agar is a substance which dissolves in hot water and sets to form a jelly. You pour hot agar containing all the necessary nutrients into a Petri dish. Then leave it to cool and set before you add any microorganisms. The other way to provide nutrients to grow microorganisms is as a broth in a culture flask. Whichever way you do it, you usually need to provide warmth and oxygen as well
You have to take care when culturing microorganisms. This applies even when the microbes you want to grow are completely harmless. There is always a risk that a mutation may take place resulting in a new and dangerous pathogen. Also you culture may be contaminated by disease causing pathogens which are present in the air, soil or water around you.
Not only do you want to avoid contamination by any dangerous microorganisms, you also need to keep any pure strains of bacteria that you are growing free from other microorganisms. There are always millions of microbes - some harmful and some not - in the air, on the lab surfaces and on your own skin. So whenever you are culturing microorganisms, you must carry out very strict health and safety procedures.