How to grow Bacteria and Fungi

Find out how to grow bacteria and fungi at Germtoons

If you have ever asked yourself how to grow bacteria and fungi you have come to the right place.  Let me show you an easy recipe for growing bacteria and fungi. But first let me tell you a little bit of background information:

As you know by now, most bacteria and fungal spores are too small to see with your plain eyes. A microscope good enough to see these microorganisms is relatively expensive, and you might not have one at your disposal.

How to grow bacteria in liquid nutrient broth

By growing bacteria in a liquid broth of nutrients, such as fruit juice or meat soup you will not be able to see individual bacteria but can see that the liquid will become turbid due to bacterial contamination and growth. This happens because the bacteria, when given enough food, will divide and divide and so on. Finally, they will have multiplied so often that you can see the horde of bacteria with your own eyes.

Bacterial Growth
                            Bacteria divide and divide and….

You can easily test this by leaving a bottle of clear juice or soup stand open for some time, then close the bottle with some aluminum foil wrap and let it stand somewhere for a couple of days.  The warmer the place where the bottle stands, the faster the bacteria will grow.

You can also actively incubate the bottle with bacteria, e.g., by putting a finger in it, or by transferring material with a cotton swab (for example from your tongue). Do not close the bottle tightly (e.g., with the lid or cap), since the bacteria may produce gas that could build up high pressure in the bottle if the bottle is tightly locked.

How to grow bacteria on solid agar plates

By growing bacteria in a liquid, you will most likely get a mixture of different bacteria and fungi. A great way to isolate specific kinds of bacteria is to incubate them on a solid growth medium. Microbiologists use agar plates (also called petri dish) for this.

If the incubation of the agar plate is done correctly, you will be able to see individual bacteria colonies on the plate. Each colony consists of the descendants of just one bacterium. They are clones.

Bacteria colonies on an agar plate
                             Bacteria colonies on an agar plate

If you want to create agar plates yourself and grow bacteria on them, you can download a great recipe below (PDF) that will guide you through all the steps in detail.

How to Grow Bacteria


As for growing fungi, you will see that it is quite easy to grow them. On the opposite, it will be a challenge to isolate just bacteria without fungi. Apart from using liquid or solid media to grow them as described above, you will easily be able to see fungi on old bread or fruit.

Spread the love - Not the Germs