Isolated polynucleotide (I) which is a zwa2 gene from Corynebacterium glutamicum, is new. Isolated polynucleotide (I) contains a sequence that is: (i) at least 70% identical with a sequence that encodes a 385 amino acid (aa) sequence (II), given in the specification; (ii) encodes a polypeptide at least 70% identical with (II); (iii) is the complement of (i) or (ii); or (iv) contains at least 15 consecutive nucleotides (nt) from (i)-(iii). Independent claims are also included for the following: (1) vectors containing (I); (2) coryneform bacteria produced by integrational mutagenesis with the vector of (1); and (3) production of L-amino acids, especially L-lysine, by growing an aa-producing bacterium in which at least the zwa2 gene has been suppressed.
