6. How can we grow bacteria and fungi safely in Science class?


Bacteria and fungi can be grown easily in a school lab with just a few pieces of equipment. Growing bacteria and fungi is called culturing.

Bacteria and fungi need water, warmth and nutrients (food) to carry out MRS C GREN. So as long as they are given these things you can culture these micro-organisms.

The bacteria and fungi are grown on an agar plate, which is a shallow plastic dish with a lid (Petri dish), filled with a special jelly made of seaweed and nutrients. The nutrients provide the food they need. The water comes from the agar jelly. The agar plates are placed in a warm place to incubate (allow time for the bacteria and fungi to carry out MRS C GREN). Often in labs an incubator is used, which is a lot like an oven but the temperature only gets to around 30°C.

So how do the bacteria and fungi get onto the agar plate? We are going to sample some places around the lab. These are the steps:

1. Collect an agar plate and identify the lid and the agar side of the dish. Do not touch the surface of the agar.

2. With a vivid pen divide the agar side of the dish into two then write your initials on the side of the dish. Select two surfaces to be sampled and write the surface name on the side of the dish, e.g. cell phone button. DO NOT sample anywhere on or in your body or anywhere unsanitary.

3. Rub a wet cotton bud over the first surface, this will pick up any bacteria or fungi on that surface.

4. Gently wipe the cotton bud side to side over the surface of the agar jelly. Any bacteria or fungi will be wiped onto the agar. Repeat again with a new clean cotton bud on the other surface.

5. With sticky tape seal the lid onto the agar dish.

6. Place the dish upside down on the teachers desk. Wash your hands.

The plates will then be incubated and in 2-3 days you will be able to see each shiny and round colony of bacteria (one “dot” is millions of bacteria) and the fluffy, branching fungi. The different colours are different types of bacteria and fungi. DO NOT open the dishes - it is unsafe. Return the plates to your teacher and wash your hands.


Nutrients: Food that is used to do MRS C GREN

Agar plate: A plastic petri dish full of jelly, used to grow bacteria and fungi.

Culturing: Growing bacteria and fungi.

Incubator: A specially designed place to incubate agar plates at warm temperatures.

Colony: Millions of bacteria in one spot on an agar plate.

Incubate: To keep agar plates at warm temperatures so that bacteria and fungi will grow.