The Discovery of Penicillin In 1928, Sir Alexander Fleming was studying Staphylococcus bacteria growing in
culture dishes. He noticed that a type of mold called Penicillium was also growing in
some of the dishes. A clear area existed around the mold because all the bacteria that
had grown in this area died.
Experiment #2:
Fleming thought that the mold must be producing a chemical that killed the bacteria. He
decided to isolate this substance and test it to see if it would kill bacteria. Fleming
transferred the mold to a liquid broth solution. This solution contained all the materials
the mold needed to grow. After the mold grew, he removed it. He then grew two identical
groups of bacteria. He then took the mold-infused broth and added it to the groups of
bacteria. Those bacteria died. Fleming then added a liquid broth that did not contain
mold to the second group of bacteria. This group survived.
1. What is the hypothesis?penicillium mold produce then it produces sorte
chemical that kills the bacteria
2. What independent variable were the scientists studying in this case?
What dependent variable were the scientists measuring?