Just a century ago, many people died from minor bacterial infections and diseases. A simple cut or strep throat could be fatal. But today, we have antibiotics that protect people from infections by killing harmful bacteria. The first of these life-saving antibiotics was penicillin, made from a type of mold that grows naturally. This "miracle drug" changed medicine forever.

Scientific name of mold: Penicillium notatum
Discovered by: Alexander Fleming, 1928
Where it grows: naturally occurring mold; needs a lot of air to grow
How it works: kills by stopping bacteria from making new cell walls
Significance: prior to discovery, many people died from simple cuts or minor infections

Image credits: main image: Eric Hamilton.