PCR detection of enzyme-encoding genes in Leuconostoc mesenteroides strains of wine origin.

Fifteen isolates of lactic acid bacteria originating from South African grape and wine samples were identified as Leuconostoc mesenteroides subsp. mesenteroides through the taxonomic analysis of their 16S rDNA gene sequences. These isolates were further tested for the presence of genes coding for enzymes of oenological relevance using PCR detection technique. A type strain of Leuc. mesenteroides (NCDO 529(T)) was also incorporated for comparative analysis. From the PCR detection results, the estA, prtP, alsD, alsS, metK, metC and metB genes were present in all the strains tested. The bgl and gshR genes encoding β-glucosidase and glutathione reductase, respectively, were not detected in some strains. On the other hand, none of the tested strains possessed the genes encoding phenolic acid decarboxylase (padA), citrate permease (citP), citrate lyase (citD, citE and citF) and arginine deiminase pathway enzymes (arcA, arcB and arcC). The verification of PCR-generated fragments was performed by sequencing. GenBank database was used to search for homologous DNA sequences. Neighbour-joining trees based on nucleotide sequences of alsS, estA, metK and mleA genes were also constructed in order to study the phylogenetic relationship between Leuc. mesenteroides strains and closely related species. The phylogenetic analyses revealed that there are genetic heterogeneities between strains of Leuc. mesenteroides species. In conclusion, this study has improved our knowledge on the genetics of oenological strains of Leuc. mesenteroides and their genetic potential to contribute to certain wine aroma compounds.