Open AccessPlasmid involvement in the formation of a spontaneous bacteriophage insensitive mutant of Lactococcus lactis
Author(s) -
Harrington Aidan,
Hill Colin
Publication year - 1992
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1992.tb05406.x
Subject(s) - plasmid , lactococcus lactis , bacteriophage , biology , mutant , microbiology and biotechnology , genetics , biovar , bacteria , dna , gene , escherichia coli , lactic acid
Lactococcus lactis subsp. lactis biovar. diacetylactis DPC721 is a spontaneous bacteriophage insensitive mutant of strain DPC220, isolated after challenge with an industrial bacteriophage, φD1. Plasmid analysis demonstrated that the bacteriophage insensitivity was associated with the absence of two native DPC220 plasmids (pAH82 and pAH33), and the presence of a novel plasmid (pAH90) in DPC721. The plasmids were transferred by conjugative mobilization to a plasmid free background where it was confirmed by restriction mapping that pAH90 is a con‐integrate formed by the precise recombination of pAH82 and pAH33. The resistance phenotype encoded by pAH90 was also active against two bacteriophage homologous for the plasmid‐free strain. Plasmid pAH90 was shown to encode at least two independent resistance mechanisms, including an adsorption‐inhibition mechanism and a restriction and modification system. The adsorption‐inhibition mechanism encoded by the co‐integrate plasmid was specific for one of the phage used in this study.