Mighty Microbes

Mighty Microbes

Learn more about our tiny friends, the microbes

Do you know how bread is made? What makes compost in the garden? How do you turn milk into cheese? Tiny living things called microbes (or micro-organisms) are responsible for all of these. Microbes are too small to see with our eyes, so we have to use a microscope to look at them. Bacteria, viruses and some fungi are all microbes.

Although you might think all microbes are nasty and cause diseases like colds and flu, most microbes are actually harmless and some are even useful.


Making bread is a brilliant example of this. A tiny fungi, called yeast, is added to bread dough. Bread dough is made of flour and water. The yeast turns the flour into sugar, which the yeast can eat. When the yeast feeds on the sugar it makes carbon dioxide. The carbon dioxide gas bubbles through the dough and causes it to rise. When the dough is baked the yeast dies. Without yeast, you wouldn't be able to have toast on a morning!

Wow! Yeast is made up of just one cell. Humans have about 100 trillion!

Bread dough_93487928

Baker kneading bread dough


We wouldn't have compost on the garden without microbes. Compost is a gardener's best friend: it helps to make a healthy soil for plants. Microbes make compost by feeding on grass, leaves and kitchen leftovers and converting them into the brown mush you see in the bottom of a compost bin. This mush has loads of nutrients that plants need to grow.


Mmm tasty cheese! Microbes are added to milk to make cheese. The microbes convert the lactose sugar in cheese to lactic acid. This makes a funny looking mixture, a bit like yoghurt. The mixture is pressed into moulds and left to mature. Cheeses like Brie and Camembert are sprayed with another microbe, to give the cheeses a special taste and texture. Blue cheeses (the ones that smell like stinky feet) have other microbes in them that  produce the blue colour and strong taste.

This video will tell you more about how microbes help us make bread and cheese.