Genetic analysis of bacteriocin production ability and phage adsorption inhibition type resistance system in six Lactococcus lactis strains

In this study, the phage adsorption inhibition type resistance system was investigated in 6 bacteriocin producing strains, Lactococcus lactis subsp. lactis BLL10, BLL27, BLL31, BLL84 and BLL90 and L. lactis subsp. cremoris BLC67. All six bacteriocin producing strains were determined to comprise phage adsorption inhibition type of resistance against three phages (Opll98-28, Opld67-41 and Opld67-43). Genetic determinants of these two systems were also analysed in these strains. The bacteriocin production abilities and phage adsorption inhibition type resistance of these strains were found to be determined by 13.4 kb and 25.3 kb plasmids in BLL10; 9.5 kb and 30.1 kb plasmids in BLL27; 10.4 kb and 29.0 kb plasmids in BLL31; 23.4 kb and 19.0 kb plasmids in BLL84; 7.5 kb and 15.3 kb plasmids in BLL90, respectively. In BLC67, both characteristics were found to be determined by 31.3 kb plasmid. Conjugal mating experiments showed that 30.1 kb plasmid in BLL27, 29.0 kb plasmid in BLL31, 23.4 kb plasmid in BLL84 and 31.3 kb plasmid in BLC67 were conjugally transferable with the frequencies of 3.6x10(-3), 8.2x10(-4), 1.4x10(-6) and 6.6x10(-3), respectively.