Tyrothricin is a complex of two unrelated peptide families, gramicidin complex and tyrocidines complex, produced by Bacillus brevis and discovered by Dubos in 1939. Typically, tyrothricin is composed of 20% of the linear pentadecylpeptide gramicidins and 80% of cyclic decapeptide tyrocidines. Both the gramicidins and tyrocidines act by disrupting bacterial cell wall integrity, but by differing mechanisms. Tyrothricin is used clinically for bacterial skin infections in some countries.
