Plasmid encoded bacteriophage resistance inStreptococcus cremorisSK11

Abstract

In Streptococcus cremoris SK11, different permutations of a total of 8 plasmids were observed within and between cultures of various origins. All showed similar growth rates in milk. Those variants which carried a 34-MDa plasmid, pSK112, were resistant to bacteriophage oSK11G, whereas those from which the plasmid was absent or had been cured were sensitive to this phage. Plasmid pSK112 was shown to confer resistance by reduced phage adsorption. These observations have important potential for the development of phage-resistant dairy cultures.