Identification and Characterization of L-Malate Dehydrogenases and the L-Lactate-Biosynthetic Pathway in Leuconostoc mesenteroides ATCC 8293

초록

One putative L-lactate dehydrogenase gene (L-ldh) and three putative D-ldh genes from Leuconostoc mesenteroides ATCC 8293 were overexpressed, and their enzymatic properties were investigated. Only one gene showed D-LDH activity, catalyzing pyruvate and D-lactate interconversion, whereas the other genes displayed L- and D-malate dehydrogenase (MDH) activity, catalyzing oxaloacetate and L- and D-malate interconversion, suggesting that strain ATCC 8293 may not harbor an L-ldh gene. Putative phosphoenolpyruvate carboxylase (PEPC)- and malolactic enzyme (MLE)-encoding genes were identified from strain ATCC 8293, and sequence analysis showed that they could exhibit PEPC and MLE activities, respectively. L-Lactate production and transcriptional expression of the mle gene in this strain were highly increased in the presence of L-malate. We propose that in strain ATCC 8293, which lacks an L-ldh gene, L-lactate is produced through sequential enzymatic conversions from phosphoenolpyruvate to oxaloacetate, then L-malate, and finally L-lactate by PEPC, L-MDH, and MLE, respectively.

키워드