Penicillin Production - The mould from which Fleming isolated penicillin, in was later identified as Penicillium notatum. A variety of moulds belonging to other species and genera were later found to yield greater amounts of the antibiotic and a series of closely related penicillins.
The naturally occuring penicillins differ from each other in the side chain (R group). Penicillin was produced by a surface culture method early in World War II. Sub-merged culture methods were introduced by 1943 and are now almost exclusively employed. Penicillin production needs strict asceptic conditions. Contamination by other microorganisms reduces the yield of penicillin.
This is caused by the widespread occurrence of penicillinase producing bacteria which inactivate the antibiotic. Secondly, penicillin production also needs tremendous around of air. In all methods, deep tanks with a capacity of several thousand gallons arc filled with a culture medium. The medium consists of cornsteep liquor, lactose, glucose, nutrient , salts, phenyl acetic acid or a derivative and calcium carbonate as buffer.
The medium is inoculated with a suspension of conidia of Penicillium chrysogenum. The medium is constantly aerated and agitated, and the mould grows throughout as pellets. After about seven days, growth is complete, the pH rises to 8.0 or above, and penicillin production ceases. When the fermentation is complete, the masses of mould growth are separated from the culture medium by centrifugation and filtration.
The complex process of extracting the penicillin from the clear fluid then begins. The method involves various extractions with organic solvents and recrystallization. Penicillin is assayed to determine its potency before being bottled and sold.