The invention relates to a process for producing L-lysine or L-lysine-containing feed additives by fermentation, which comprises a) expressing a polynucleotide coding for polypeptide having LL-diaminopimelate aminotransferase activity in a bacterium excreting L-lysine, and b) fermenting the resultant bacterium in a medium under suitable conditions and allowing the resultant L-lysine to accumulate in the fermentation broth.