Comparison of partial malolactic enzyme gene sequences for phylogenetic analysis of some lactic acid bacteria species and relationships with the malic enzyme.

Abstract

DNA sequences covering 36% of the mle gene that encodes the malolactic enzyme were determined for 13 strains of lactic acid bacteria, representing Pediococcus, Leuconostoc, Lactobacillus and Oenococcus genera. The sequences were aligned with the corresponding region of mleS in Lactococcus lactis. The phylogenetic distance matrix tree of all mle sequences was compared with the 16S rRNA phylogenetic tree. The analysis showed that the mle fragment evolved more rapidly than the 16S gene and differently. Pediococcus and Lactobacillus species were intermixed in the 16S rRNA tree whereas they were separated in the mle tree. Leuconostoc mesenteroides and Oenococcus oeni were distinct from other species in the 16S rRNA tree, whereas they were intermixed with Lactobacillus species and Lactococcus lactis in the mle tree. The amino acid sequences deduced from partial mle genes were aligned with 22 malic enzyme sequences and the corresponding phylogenetic tree was constructed. Malic and malolactic enzymes were distinct at the phylogenetic level, except for malic enzymes of yeast and Escherichia coli which were nearer the malolactic enzymes than the other malic enzymes. The analysis of conserved sites showed several interesting amino acids specific to either malic enzyme or malolactic enzyme.