Diversity analysis of dairy and non-dairy strains of Lactococcus lactis ssp. lactis by multilocus sequence analysis (MLSA)

The genetic diversity of 31 identified strains of Lactococcus lactis ssp. lactis isolated from different dairy and non-dairy sources were investigated at gene level using multilocus sequence analysis (MLSA) and PCR-RFLP based on the differences in four selected partial protein coding gene sequences: araT, encoding aromatic amino acid-specific aminotransferase; dtpT, encoding di/tri peptide transporter; yueF, encoding non-proteolytic protein, peptidase, M16 family; and pdhA, encoding pyruvate dehydrogenase E1 component α-subunit. A set of seven test strains from different isolation sources and one reference strain, L. lactis ssp. lactis NCDC 094, were analyzed by MLSA. The strains showed distinct diversity among themselves and exhibited a greater percent similarity with reference strains L. lactis ssp. lactis CV56 (CP002365.1), IL1403 (AE005176.1), and KF147 (CP001834.1) in comparison with L. lactis ssp. cremoris NZ9000 (CP002094.1), MG1363 (AM406671.1), and SK11 (CP00425.1). The MLSA revealed one distinct genomic lineage within strains exclusively of L. lactis ssp. lactis. This analysis also revealed no source-wise genetic relationship in the test strains analyzed. Further, PCR-RFLP of araT, dtpT, yueF and pdhA also characterized the single genomic lineage exclusively of L. lactis ssp. lactis within a total of 24 test strains.