Bacteria and us
Bacteria are as useful to people as they are harmful. The same group works both ways.
When they help
- Producing yoghurt and cheese from curdled milk.
- Obtaining fibre from coconut husk and hemp leaves, and tanning hides.
- Fixing atmospheric nitrogen, which raises the nitrate in the soil.
When they harm
- Causing various diseases in people and in other organisms.
- Spoiling food.
Diseases caused by bacteria
Tuberculosis
Pneumonia
Cholera
Tetanus
Leprosy
Nitrogen fixing is the biggest of them
The atmosphere is 78% nitrogen, and yet no plant can use it directly. What turns it into nitrate in the soil is bacteria — so every plant, and therefore every animal, depends on them.