Nisin, a bacteriocin produced by some strains of Lactococcus lactis, acts against foodborne pathogen Listeria monocytogenes. A single exposure of cells to nisin can generate nisin-resistant (Nisr) mutants, which may compromise the use of nisin in the food industry. The objective of this research was to compare the heat resistance of Nisr and wild type (WT) Listeria monocytogenes. The synergisti...

One exciting area that has emerged through genetic analysis of the lactococci is the definition and practical application of gene systems that provide phage resistance to these industrially important bacteria. Naturally occurring phage-insensitive strains have been characterized and found to harbour multiple defence systems which can act at different points of the lytic cycle to prevent the suc...

The genome sequence of Lactococcus lactis subsp. cremoris Mast36, isolated from bovine mastitis, is reported here. This strain was shown to be able to grow in milk and still possess genes of vegetable origin. The genome also contains a cluster of genes associated with pathogenicity.

We describe here a new lactococcal abortive phage infection system, designated AbiP. AbiP is effective against some lactococcal phages of one prevalent group, 936, but not against phages from the other two groups (c6A and P335). It was identified in the Lactococcus lactis subsp. cremoris strain IL420, on the native plasmid pIL2614. AbiP is encoded by a single gene, expressed in an operon with a...

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DNA-DNA homology between a reduced bacteriophage sensitivity (Rbs+) probe and DNA from both Rbs+ and Rbs- Lactococcus lactis strains was examined. Homology was detected between the probe and five plasmids (pCI750, pCC34, pEB56, pNP2, and pJS88) isolated from lactose-positive Rbs+ transconjugants and between the probe and genomic DNA of a sucrose-positive Rbs+ transconjugant. Additionally, hybri...

Several Lactococcus lactis strains produce the lantibiotic nisin. The dedicated enzymes NisB and NisC and the transporter NisT modify and secrete the ribosomally synthesized nisin precursor peptide. NisB can function in the absence of the cyclase NisC, yielding the dehydrated prenisin that lacks the thioether rings. A kinetic analysis of nisin production by L. lactis NZ9700 demonstrated that th...

BACKGROUND Despite their functional and biotechnological importance, the study of membrane proteins remains difficult due to their hydrophobicity and their low natural abundance in cells. Furthermore, into established heterologous systems, these proteins are frequently only produced at very low levels, toxic and mis- or unfolded. Lactococcus lactis, a gram-positive lactic bacterium, has been tr...

We report the genome, in a single chromosome, of Lactococcus lactis strain AI06, isolated from the mesocarp of the açaí fruit (Euterpe oleracea) in eastern Amazonia, Brazil. This strain is an endophyte of the açaí palm and also a component of the microbiota of the edible food product.

Two 2,3-butanediol dehydrogenases (enzymes 1 and 2; molecular weight of each, 170,000) have been partially purified from Lactococcus lactis subsp. lactis (Streptococcus diacetylactis) D10 and shown to have reductase activity with either diacetyl or acetoin as the substrate. However, the reductase activity with 10 mM diacetyl was far greater for both enzymes (7.0- and 4.7-fold for enzymes 1 and ...