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.
Bread
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!
Baker
kneading bread dough
Compost
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.
Cheese
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.