An isolated mutant of coryneform bacteria comprising a gene encodes a polypeptide having 2-methylcitrate dehydratase activity, where the polypeptide comprises an amino acid sequence in which one of the proteinogenic amino acids except L-proline is present at position 272 or a corresponding or comparable position. In addition, an isolated polynucleotide encoding a polypeptide having 2-methylcitrate dehydratase enzymic activity, which comprises at position 272 of the amino acid sequence or a corresponding or comparable position a proteinogenic amino acid except L-proline is described. A method for producing a recombinant coryneform bacterium and L-amino acids. A recombinant microorganism, L-Lysine-containing feed additive, and L-Tryptophan-containing feed additive is also described.