A process for the preparation of L-amino acids, in particular L-threonine is disclosed herein. In particular, a process for the preparation of L-amino acids in Enterobacteriaceae, comprising fermenting, in a medium, Enterobacteriaceae which produce L-amino acid and in which E. coli ahpC and ahpF is overexpressed, and concentrating the L-amino acids in the medium or in the Enterobacteriaceae is disclosed.