Open AccessIdentification of three different plasmid‐encoded restriction/modification systems in Streptococcus lactis subsp. cremoris W56
Author(s) -
Josephsen Jytte,
Vogensen Finn K.
Publication year - 1989
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.1574-6968.1989.tb03102.x
Subject(s) - plasmid , biology , transformation (genetics) , genetics , bacteriophage , strain (injury) , restriction map , dna , microbiology and biotechnology , gene , escherichia coli , anatomy
Streptococcus lactis subsp. cremoris W56 ( S. cremoris W56) is a strain partially resistant to phage attack. Derivatives which had lost either plasmid pJW563 or pJW566 no longer expressed the restriction and modification systems encoded by these plasmids. Genetic evidence for the correlation between the plasmids and the R/M systems was obtained by transformation. In addition, a third R/M system was discovered among the transformants and was shown to be encoded by pJW565. Thus, genetic evidence for at least 3 distinct R/M systems encoded by plasmids in S. cremoris W56 is presented. One of the R/M‐systems showed stronger restriction of the isometric phage p2 than of the prolate phage c2. The other two systems restricted both classes of phages with equal efficiencies.