Penicillin: History, Structure, Production and Recovery

Penicillin: History, Structure, Production & Recovery


  • Introduction
  • History
  • Structure
  • Penicillin molecule and its precussor
  • Penicillinase
  • 6- amino penicillanic acid
  • Penicillin production


  • 1st antibiotic to be produced and still one of the best antibiotic available.
  • Penicillin is a group of antibiotics, isolated from common molds known as Penicillium Molds.
  • It is active against many gram-positive bacteria, Nocardia, Actinomycetes.
  • It generally, interferes with cell wall synthesis of organisms which is sensitive and it is active only against vegetative cell.


  • Sir, Alexander Fleming in 1929, first observed the antibiotic properties and possible therapeutics value of penicillin.

History of Penicillin

  • He observed that an airborne contaminant, later shown to be Penicillium notatum inhibited the growth of a culture of Staphylococcus aureus on agar medium in the area surrounding the fungal activity.
  • Fleming further showed that this inhibitory effect Caused by a soluble, diffusible mold product.
  • Penicillin observed by Fleming was Penicillin-G.


  • Several penicillins are closely related in structure.
  • Common chemical nucleus and a side chain attached to this nucleus.

Structure of Penicillin

  • Various compounds resembling the side chain can be added as precursor to fermentation medium & through microbial strain are directly incorporated into Penicillin molecule.
  • Fungi: Aspergillus & Penicillium.
  • Various penicillin differs as nature of their “R’’ side chain.

Penicillin molecule and its Precursor

Penicillin molecule and its Precursor

  • Whereas, in present day commercial terms penicillin is regarded as the Penicillin-G.
  • The Penicillin nucleus consists of two amino acids, L-cysteine and D-valine.


  • Penicillinase is an extracellular enzyme adaptively produced by members of the coliform group of bacteria, by most Bacillus sp.
  • Major factor for penicillin resistance during infection.
  • This enzyme hydrolyses penicillin to penicilloic acid.

6-amino penicillanic acid

  • Sensitive to Penicillinase enzyme.
  • Can be recovered from fermentation broth.
  • Chemically converted to penicillin by chemical addition of various R side chains. Yield of this material is low.
  • Penicillin acylase enzyme cleaves side chains of penicillin so resulted in commercial production 6-Amino penicillanic acid.

Penicillin production

  • Commercially, penicillin was first produced in stationary mat culture.
  • Production of penicillin is previously achieved by surface process i.e. solid-state fermentations and surface liquid fermentation.

Penicillin production

Penicillin production mainly consists of three steps:

    1. Inoculum preparation
    2. Production fermentation
    3. Product recovery

Inoculum preparation

  • Inoculum: Penicillium chrysogenum.
  • For inoculum production, spores from heavily sporulated working stocks (special agar sporulation) are suspended in water or in a dilute solution of a nontoxic wetting agent, such as  1:10,000 sodium lauryl sulfonate.
  • These spores are then poured in the flask which contains wheat bran and nutrient solution for heavy sporulation.
  • Incubate for at 24°C for 5-7 days to provide heavy sporulation.
  • Resulting spores are directly inoculated into inoculation tanks.
  • Incubated at 25 to 26°C for 3 to 5 days exact duration of fermentation depends on various factors.

Production fermentation

  • Method: fed batch or batch.
  • Media: (Jackson 1958)
    1. Corn steep liquor solids-3.5%
    2. Lactose: 3.5%
    3. Cellulose: 1%
    4. CaCO3: 1%
    5. K2HPO4: 0.4%
  • Edible oil:  0.25%
  • Fermenter: stirred tank or air lift tank.
  • Temperature: 25-27°C.
  • Aeration: 0.5 – 27 1 VVM.
  • Anti-foam: edible oil
  • pH: set at 5.5 to 6.0 which increased up to 7-7.5.
  • Inoculum media is same as production media.
  • Lactose precursor is not added, at start of fermentation.
  • PH remain constant, glucose, corn steep liquor, Carbon compounds and ammonia are utilised.
  • Carbon compounds depleted, pH rise to 7-7.5.
  • At the end of fermentation pH rises to 8 higher because depletion of lactose brings an autolysis in mycelium.
  • Penicillium is harvested before this.

Product Recovery

  • Harvest broth from fermenter tank by filtration.
  • Chill to 5-10°C.
  • Acidify filtrate to pH 2.0 to 2.5 with H2SO4.
  • Penicillin extracted from  aqueous filtrate into butyl acetate or amyl acetate.

Product recovery of Penicillin

  • Discard aqueous fraction
  • Add potassium acetate to the solvent extract in a crystallization tank to crystallize as potassium salt.
  • Recover crystal from centrifuge.
  • Further processing.
  • Packaging.

Reference and Sources

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Penicillin: History, Structure, Production & Recovery

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