NEW MATERIAL:A lysine derivative of formula I and an acid addition salt thereof.

EXAMPLE: The compound of formula II.

USE: A phage inhibitor capable of preventing the damage by the phage infection in the fermentation industry. 10-3W10-6M the derivative is added to a culture medium in the amino acid fermentation, e.g. L-lysine or L-glutamic acid, the nucleic acid fermentation, e.g. inosine or guanosine, and the organic acid fermentation, e.g. citric acid or lactic acid.

PROCESS: An active ester of azelaic acid is condensed with ethyl ester of lysine having a protected -amino group, and the protecting group is removed to give the compound of formula I. The active ester of the azelaic acid is obtained by reacting azelaic acid with n-hydroxysuccinimide and dicyclohexylimide in an inert solvent under cooling in ice.