Identification of three different plasmid-encoded restriction/modification systems in Streptococcus lactis subsp. cremoris W56 |
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Authors: | Jytte Josephsen Finn K Vogensen |
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Institution: | Department of Dairy Science, The Royal Veterinary and Agricultural University Bülowsvej 13, DK-1870 Frederiksberg C., Denmark |
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Abstract: | Abstract 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. |
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Keywords: | Streptococcus lactis Restriction and modification Phage restriction Streptococcus cremoris W56 |
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