Bacteria, can’t live with them, and can’t live without them. Bacteria
make some of the world’s oxygen, produce all of Earth’s nitrogen, composts
pollutants, and are essential to the human digestive process.
Pasteur (1822-1895) was the first to trap airborne organisms and disproved
the theory that life grew from nothing.
Koch developed Koch’s Postulates, used to establish the link between a
disease and a particular organism. He would extract the organism thought to
cause the disease, isolate and culture the disease, and test the pathogen on
a healthy organism. If the same disease occurred, then he would know what
organism caused the disease.