第2期:认识细菌(2)

Actually less than 1% of all bacteria cause disease. The others perform countless useful functions in everyday lives.

Bacteria are behind many of our favorite foods. And when those foods spill down the front of us, bacterial enzymes help get the stains out.

Even artificial snow relies on bacteria. Protein from freeze-dried bacteria helps flakes to form out of water mist.

Bacteria are the oldest life-form on earth. They survive even thrive in some of the harshest environments.

In the hot springs of Yellowstone, in pools of acid, in caves in crevices in the earth without light or air, next to ocean vents where the water temperature is 480 degrees Fahrenheit.

This is what a bacterium is. A single-cell organism with its own branch on the tree of life.

Daisies, squirrels and people are on the other side. Because their bodies are made up of many cells.

It's the smallest of three living organisms. About a million would fit on the head of a pin.

Viruses are a hundred times smaller, but they have to move into a host cell to survive. Bacteria come in a variety of shapes and sizes and to reproduce they simply divide.

In many species, cell division occurs every 20 minutes. Bacteria have studied us more closely and more lovingly than any other creature.