Improvement of phage defence in Lactococcus lactis by introduction of the plasmid encoded restriction and modification system LlaAI.
OBJECTIVE
To study the ability of the plasmid-encoded restriction and modification (R/M) system LlaAI to function as a bacteriophage resistance mechanism in Lactococcus lactis during milk fermentations.


RESULTS
Plasmid pAIcat4, carrying the R/M system LlaAI and a chloramphenicol resistance cassette, was introduced into the plasmid-free strain L. lactis MG1614 and the industrial strain L. lactis 964. By measuring changes in conductivity the influence of different phage on the growth was determined.


CONCLUSIONS
The plasmid-encoded R/M system LlaAI significantly improves the bacteriophage resistance of L. lactis during milk fermentations.


CONCLUSIONS
It is essential to determine the potential of a phage defence mechanism in L. lactis starter culture strains during growth in milk before steps are taken to improve starter cultures. This study shows that LlaAI is useful for improvement of starter cultures.
Gabs
S
S
Danisco Cultor Niebüll GmbH, Niebüll, Germany.
Josephsen
J
J
D000818:Animals; D001435:Bacteriophages / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D002702:Chloramphenicol Resistance / Q000235:genetics; D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005285:Fermentation; D013294:Lactococcus lactis / Q000201:enzymology / Q000254:growth & development / Q000821:virology*; D008892:Milk / Q000378:metabolism; D008957:Models, Genetic; D010957:Plasmids
D015252:Deoxyribonucleases, Type II Site-Specific; C024405:GATC-specific type II deoxyribonucleases