Abstract

An over-expressed L-ldh gene derivative of Escherichia coli BAD-ldh was developed. L-ldh gene from Enterococcus facelis KK1 consisted of an open reading frame of 954 bp encoding 316 amino acids. L-ldh gene was cloned into pBAD vector and transformed into E. coli SZ85 by electroporation. SDS-page and western blotting method confirmed the presence of recombinant L-LDH enzyme with the approximate size of 40 kD. The activity of L-lactate dehydrogenase was achieved at 170 U ml^-1. E. coli BAD85 was found to produce 0.62 g l^-1 of lactic acid from 1 g l^-1of fructose in 24 h. L-ldh gene from was successfully transformed into E. coli SZ85 with the maximum production of L-lactic acid at 0.62 g l^-1.

Key words: Enterobacter, fermentation processes, genes, lactic acid bacteria, molecular genetics, L-ldh gene.