Production methods and tools Classical strain development: Bacteria do not normally excrete amino acids in significant amounts because regulatory mechanisms control the amino acid synthesis in an economical way. a great number of amino-acid-producing bacteria have been derived by mutagenesis and screening programmesProduction methods and tools Classical strain development: Bacteria do not normally excrete amino acids in significant amounts because regulatory mechanisms control the amino acid synthesis in an economical way. A great number of amino-acid-producing bacteria have been derived by mutagenesis and screening programmes