scholarly journals Mobile CRISPR/Cas-Mediated Bacteriophage Resistance in Lactococcus lactis

PLoS ONE ◽  
2012 ◽  
Vol 7 (12) ◽  
pp. e51663 ◽  
Author(s):  
Anne M. Millen ◽  
Philippe Horvath ◽  
Patrick Boyaval ◽  
Dennis A. Romero
Keyword(s):  
Lactococcus Lactis ◽  
Bacteriophage Resistance

scholarly journals The Plasmid Complement of Lactococcus lactis UC509.9 Encodes Multiple Bacteriophage Resistance Systems

2014 ◽  
Vol 80 (14) ◽  
pp. 4341-4349 ◽  
Author(s):  
Stuart Ainsworth ◽  
Jennifer Mahony ◽  
Douwe van Sinderen
Keyword(s):  
Lactococcus Lactis ◽  
Starter Cultures ◽  
Phenotypic Traits ◽  
Abortive Infection ◽  
Content Type ◽  
Bacteriophage Resistance ◽  
Escape Mutants ◽  
Fermented Dairy Products ◽  
Fermented Dairy ◽  
Dairy Starter

ABSTRACTLactococcus lactissubsp.cremorisstrains are used globally for the production of fermented dairy products, particularly hard cheeses. Believed to be of plant origin,L. lactisstrains that are used as starter cultures have undergone extensive adaptation to the dairy environment, partially through the acquisition of extrachromosomal DNA in the form of plasmids that specify technologically important phenotypic traits. Here, we present a detailed analysis of the eight plasmids ofL. lactisUC509.9, an Irish dairy starter strain. Key industrial phenotypes were mapped, and genes that are typically associated with lactococcal plasmids were identified. Four distinct, plasmid-borne bacteriophage resistance systems were identified, including two abortive infection systems, AbiB and AbiD1, thereby supporting the observed phage resistance ofL. lactisUC509.9. AbiB escape mutants were generated for phage sk1, which were found to carry mutations inorf6, which encodes the major capsid protein of this phage.

scholarly journals Bacteriophage Resistance of a ΔthyA Mutant of Lactococcus lactis Blocked in DNA Replication

2002 ◽  
Vol 68 (6) ◽  
pp. 3010-3023 ◽  
Author(s):  
Martin B. Pedersen ◽  
Peter R. Jensen ◽  
Thomas Janzen ◽  
Dan Nilsson
Keyword(s):  
Dna Replication ◽  
Lactococcus Lactis ◽  
Thymidylate Synthase ◽  
Gene Replacement ◽  
Multiplicity Of Infection ◽  
Normal Amount ◽  
Bacteriophage Resistance ◽  
Acetaldehyde Production

ABSTRACT The thyA gene, which encodes thymidylate synthase (TS), of Lactococcus lactis CHCC373 was sequenced, including the upstream and downstream regions. We then deleted part of thyA by gene replacement. The resulting strain, MBP71 ΔthyA, was devoid of TS activity, and in media without thymidine, such as milk, there was no detectable dTTP pool in the cells. Hence, DNA replication was abolished, and acidification by MBP71 was completely unaffected by the presence of nine different phages tested at a multiplicity of infection (MOI) of 0.1. Nonreplicating MBP71 must be inoculated at a higher level than CHCC373 to achieve a certain pH within a specified time. For a pH of 5.2 to be reached in 6 h, the inoculation level of MBP71 must be 17-fold higher than for CHCC373. However, by adding a limiting amount of thymidine this could be lowered to just 5-fold the normal amount, while acidification was unaffected with MBP71 up to an MOI of 0.01. It was found that nonreplicating MBP71 produced largely the same products as CHCC373, though the acetaldehyde production of the former was higher.

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