Fleming's discovery of penicillin in 1928 arose from which laboratory occurrence?

Fleming's discovery of penicillin in 1928 arose from which laboratory occurrence?

• A. A laboratory contaminant
• B. A designed experiment
• C. A calculation error
• D. A contaminated culture

Answer: (A)

Fleming’s breakthrough came from an unintended mold contaminant on a plate containing Staphylococcus. The Penicillium mold landed in the culture and inhibited bacterial growth around it, leaving a clear zone. This accidental contamination revealed that a substance produced by the mold could kill or stop the bacteria, which he named penicillin. The event was not the result of a designed experiment or a calculation error, but of a contaminant in the lab—an unexpected occurrence that led to a major medical advance.

Fleming’s breakthrough came from an unintended mold contaminant on a plate containing Staphylococcus. The Penicillium mold landed in the culture and inhibited bacterial growth around it, leaving a clear zone. This accidental contamination revealed that a substance produced by the mold could kill or stop the bacteria, which he named penicillin. The event was not the result of a designed experiment or a calculation error, but of a contaminant in the lab—an unexpected occurrence that led to a major medical advance.