• First antibiotic to be produced on a large scale.
• Active against many gram positive bacteris, Nocardia, & actinomyces.
• At higher dosage it can act against gram negative bacteria.
• Interferes with cell wall synthesis hence is active only against growing cells.
• Produced by P. chrysogenum, P. notatum.

History

• 1929- Sir Alexander Fleming first observed the antibiotic properties & possible therapeutic value of penicillin.He observed penicillin production in P.notatum which is now designated as Penicillium F

• 1930- Other works showed that penicillin is an organic acid & can be extracted at low pH using organic solvents.But the penicillin extracted was found to be easily destroyed by acidity & heat.

• 1940- Penicillin was reinvestigated by English workers Chain et al & they proposed the extraction process of penicillin from P.notatum culture broth at low pH & Low temperature.

• 1951- Penicillin chrysogenum was isolated from a moldy fruit & it was mutated to produce strain Q-176, where P.chrysogenum produced 200 units of penicillin per ml while Q-176 produced 1000 units. However these strains produced water soluble pigment chrysogenin which provided a yellow tint to penicillin which was reduced by firther mutation & selection of the parental strains.