Article Abstract:
The determinants for two bacteriophage resistance mechanisms, AbiE and AbiF, are separated by about 3,300 nucleotides on the lactococcal plasmid pNP40. Two open reading frames (ORFs) which are transcribed in the opposite direction to the Abi determinants have been identified. One of these ORFs encodes a recA homolog. The second ORF shares homology with the umuC gene of the SOS response. The proximity of the recA and umuC homologs indicated a possible role in the phage resistance encoded by the Abi determinants. However, there was no evidence of a function for either ORF in the expression of either AbiE or AbiF.
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Article Abstract:
An easy, rapid plasmid mini-prep procedure for lactococci and lactobacilli which gives high yields and can be performed on overmight broth cultures is studied by isolation of large plasmids from both lactococci and lactobacilli, and also a 70-kb plasmid from Lactobacillus acidophilus C7. The purity of the resulting plasmid DNA makes it ideal for further molecular manipulations. The rapid mini-prep procedure is appropriate for routine plasmid isolation from lactic acid bacteria and other gram-positive bacteria.
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Article Abstract:
Bacteriophage resistance mechanisms derived from a bacteriophage genome called Per (phage-encoded resistance) is present in Lactococcus lactis NCK203. Per50, cloned from phage phi-50, interferes with phi-50 duplications. The Per50 fragment provides little safe-guard to NCK203. Phi-50 infection is present in a low-copy-number plasmid pTRK 325. Per31 cloned from phage phi 31 enables replication of Per31-containing plasmids, in NCK203 or phi-31 infection.
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