Helpful and Harmful Microbes

0:00Are all microbes harmful germs, or can some of them help us?

0:05Microbes, short for microorganisms, are so tiny that most can only be seen with a microscope.

0:13They include bacteria, viruses, and fungi such as yeasts and moulds.

0:19Some bacteria and viruses cause disease. Microbes like these are called pathogens, or germs.

0:27For example, strep throat is caused by bacteria, and the flu is caused by a virus.

0:33But many microbes are helpful, and the food industry puts them to work.

0:38Bacteria and moulds ripen cheese, giving it its flavour and texture.

0:44Bacteria also ferment salami. Fermentation is when microbes break down sugar; here they make an acid that gives salami its tang.

0:53In bread dough, yeast ferments sugar and gives off carbon dioxide gas, which makes the dough rise.

1:02Microbes matter in agriculture too. In the 1600s, striped tulips called broken tulips were rare and very valuable.

1:12Their stripes came from a virus, spread from plant to plant by small insects called aphids.

1:19The virus also weakened the bulbs, so it harmed the plants even though people loved the flowers.

1:26In fact, most microbes are not germs. Only some cause disease, and most are harmless or even helpful.

1:35Some microbes cause disease in people and plants, but most are harmless, and many are helpful.