원문정보
초록
영어
Lactobacillus sp. RKY2, which was isolated from a Korean traditional fermented food soybean paste, previously proved to be an efficient lactic acid bacterium for the production of lactic acid, because it could produce a large amount of lactic acid, with high productivity. The structural gene of D(-)-lactate dehydrogenase (D-LDH) was cloned from Lactobacillus sp. RKY2. The gene from chromosomal DNA was amplified by polymerase chain reaction (PCR) using a pair of
conserved sequences existed in D-LDH as primers. Approximately 1 kb of PCR product in size was cloned into an gene expression vector and the nucleotide sequence was determined. Analysis of this sequence identified a putative 999 bp D-LDH open reading frame that encodes a polypeptide of 332 amino acid residues with a deduced molecular mass of 36.5 kDa. After IPTG induction, the D-LDH was expressed in Escherichia coli. The electrophoretically pure enzyme
preparation migrated as a single band corresponding to the deduced molecular mass during SDS-PAGE. The amount of lactic acid produced by D-LDH mutant and its ldh-complemented derivative was determined by HPLC and anzymatic analysis.