Which two α−amino acids are the biosynthetic precursors of the penicillins?

L-cysteine and L-valine

Penicillin is a secondary metabolite commonly found in the filamentous fungi and they are synthesized from the amino acid precursors L-cysteine, L-valine and l-α-aminoadipic acid. β-lactam antibiotic penicillin are antibiotics commonly used for the treatment or therapy of infectious diseases.