Bacteria

There are thousands of different kinds of bacteria.   These tiny living things are too small to be seen
with the naked eye.   They are one of the simplest forms of life and are more like plants than animals, though they show characteristics of both.

Bacteria take many shapes.  Some are round, others are wormlike or spiralled.  Still others are red-shaped. These microscopic organisms are found everywhere - in our bodies, in the soil, in food, on just about everything we touch.

Many bacteria are helpful.  There are bacteria in the soil that help to break down, or decay, animal and vegetable matter.  Those in our digestive systems help break down food nutrients for the body.  Harmful bacteria include germs that cause disease and those that make food spoil.   Bacteria multiply very quickly.  From one bacterium there can be millions in only a few hours. 
Louis Pasteur was the first to study the effects of bacteria and to discover  that  it was the bacteria that made food spoil.