Evaluation of the genetic polymorphism among Lactococcus lactis subsp. cremoris strains using comparative genomic hybridization and multilocus sequence analysis

Genetic diversity of Lactococcus lactis subsp. cremoris provides an important reservoir of industrial functions. Knowledge of strain diversity is an important step for the selection of starter cultures, because technological and sensorial attributes are strain-dependent and it may help to distinguish strains with particular technological properties and performances. In the present study, microarray-based comparative genomic hybridization (CGH) and multilocus sequence analysis (MLSA) were used to investigate the genetic variation among eight strains of Lactococcus lactis subsp. cremoris. The CGH analysis allows strain grouping and identification of absent or divergent genes involved in metabolism, amino acid biosynthesis, osmoregulation and proteolysis. The MLSA clustering of strains based on the partial sequence of eight genes shows good correlation with the CGH grouping. Strains HP, ATCC 19257 and Wg2 were clustered together, followed by E8, and finally SK11 was in a separate cluster. The combined information provides genetic markers for distinguishing between strains and their variants. By selecting strains according to their genetic profiles, compatible and complementary mixed starters can be formulated, opening new avenues for industrial applications.