Pharmaceuticals by direct fermentation

Equation 9.8 shows a simplified scheme of the biosynthesis of penicillin. It starts with the amino acids L-a-aminoadipic acid and L-cysteine from penicillin N in a complex reaction sequence. When phenyl acetic acid is added to the fermentation medium, the side chain of the molecule is modified and the resulting product is called penicillin G. Today, several hundred antibiotics are on the market, most of them have at least one fermentation step in the production process. The production of antibiotics is in the order of 50,000 t/year. 

Unfortunately, bacteria develop a resistance against penicillin. Therefore, it is necessary to continuously develop new antibiotics. This can be done by modification of penicillin either by adding new functional groups or by using other microorganisms that produce different classes of antibiotics. 

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