Abstract
Two fragments conferring partial phage resistance were located on plasmid pNP40 from Lactococcus lactis ssp. lactis biovar diacetylactis DRC3 and cloned. A 2.3-kb PstI fragment from pNP40 containing abiF conferred partial phage resistance to prolate-headed phage c2, and a 4.8-kb PstI fragment of pNP40 containing abiE conferred partial phage resistance to small isometric-headed phage sk1. When each of the two fragments was cloned individually into a plasmid containing the abortive phage infection gene abiD from L. lactis ssp. lactis KR5, phage resistance was enhanced. When cloned with abiD, the 2.3-kb PstI fragment enhanced the resistance against prolate-headed phages, as was indicated by a 400-fold decrease in the efficiency of plating compared with that of abiD alone. When the 4.8-kb PstI fragment of pNP40 was cloned with abiD, resistance to small isometric-headed phages was enhanced, as was indicated by a greater than 50-fold decrease in efficiency of plating compared with that of abiD alone. The 4.8-kb PstI fragment of pNP40 cloned with abiD showed a large decrease (500- to 1000-fold) in efficiency of plating against prolate-headed phages, even though the 4.8-kb PstI fragment of pNP40 by itself conferred no resistance to the prolate-headed phages.
Published Version
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