title: Improvement of phage defence in Lactococcus lactis by introduction of the plasmid encoded restriction and modification system LlaAI.
abstract: 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.
authors.affiliation: Danisco Cultor Niebüll GmbH, Niebüll, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Gabs
authors.forename: J
authors.initials: J
authors.lastname: Josephsen
mesh_terms: 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
chemical_list: D015252:Deoxyribonucleases, Type II Site-Specific; C024405:GATC-specific type II deoxyribonucleases