초록
<P><B>ABSTRACT</B><P> Determination of the complete nucleotide sequence of a cryptic plasmid, pMBLT00, from Leuconostoc mesenteroides subsp. mesenteroides KCTC13302 revealed that it contains 20,721 bp, a G+C content of 38.7%, and 18 open reading frames. Comparative sequence and mung been nuclease analyses of pMBLT00 showed that pMBLT00 replicates via the theta replication mechanism. A new, stable Escherichia coli-Leuconostoc shuttle vector, pMBLT02, which was constructed from a theta-replicating pMBLT00 replicon and an erythromycin resistance gene of pE194, was successfully introduced into Leuconostoc , Lactococcus lactis , and Pediococcus . This shuttle vector was used to engineer Leuconostoc citreum 95 to overproduce d -lactate. The L. citreum 95 strain engineered using plasmid pMBLT02, which overexpresses d -lactate dehydrogenase, exhibited enhanced production of optically pure d -lactate (61 g/liter, which is 6 times greater than the amount produced by the control strain) when cultured in a reactor supplemented with 140 g/liter glucose. Therefore, the shuttle vector pMBLT02 can serve as a useful and stable plasmid vector for further development of a d -lactate overproduction system in other Leuconostoc strains and Lactococcus lactis . </P></P>