Efficient use of lactose for the lac promoter-controlled overexpression of the main antigenic protein of the foot and mouth disease virus in Escherichia coli under fed-batch fermentation conditions.

Abstract

Derivatives of the lac promoter (tac, pac, rac) belong to the strongest bacterial promoters which are frequently used for the induced overexpression of foreign genes in Escherichia coli. However, their use in fermentation processes is strongly restricted because of the high cost of the inducer iso-propyl-beta-D-thiogalactopyranoside (IPTG). The aim of this work was to investigate the possibility of using lac-derived promoters in high cell density processes resulting in a high yield of the induced recombinant protein if glucose is the main carbon and energy source. Lactose is tested as inducer of the main antigenic coat protein (VP1) of the foot and mouth disease (FMD) virus in a T7-RNA polymerase expression system. It was shown that lactose is able to induce the expression of the recombinant gene to an amount of the VP1 protein corresponding to 20% of the total cell protein.