Denis P. Twomey

Learn More
We assessed the effectiveness of a novel dry cow treatment containing lacticin 3147 using deliberate challenge studies in lactating cows. Infection-free quarters of lactating cows were infused with Teat seal (Cross Vetpharm Group, Ltd., Dublin, Ireland) combined with the food-grade bacteriocin, lacticin 3147. Natural infection of the teat was simulated by(More)
While much of the applied research carried out to date with bacteriocins has concerned nisin, lactococci produce other bacteriocins with economic potential. An example is the two component bacteriocin lacticin 3147, which is active over a wide pH range and has a broad spectrum of activity against Gram-positive bacteria. Since the genetic determinants for(More)
This study identifies a natural system in Lactococcus lactis, in which a restriction modification specificity subunit resident on a 6159 bp plasmid (pAH33) alters the specificity of a functional R/M mechanism encoded by a 20.3 kb plasmid, pAH82. The new specificity was identified after phenotypic and molecular analysis of a 26.5 kb co-integrate plasmid(More)
Lantibiotics are a diverse group of heavily modified antimicrobial and/or signalling peptides produced by a wide range of bacteria, including a variety of lactic acid bacteria. Based on their diverse structures and mode of action, at least six separate lantibiotic subgroups can be suggested, but all subgroups are characterized by significant(More)
The bacteriophage resistance plasmid pAH90 (26,490 bp) is a natural cointegrate plasmid formed via homologous recombination between the type I restriction-modification specificity determinants (hsdS) of two smaller lactococcal plasmids, pAH33 (6,159 bp) and pAH82 (20,331 bp), giving rise to a bacteriophage-insensitive mutant following phage challenge (D.(More)
A preparation of the bacteriocin lacticin 3147 (prepared from a demineralized whey protein fermentation liquor) was combined as a powder with a bismuth-based intramammary teat seal and evaluated for its potential as an antimicrobial in non-lactating cows. The lacticin/teat seal formulation enabled significant bacteriocin release from the seal without the(More)
Even though enterococci are a common cause of human infection they can readily be isolated from a range of food sources, including various meat and dairy products. An enterococcal strain, DPC5280, which exhibits a broad spectrum of inhibition against many Gram-positive bacteria was recently isolated from an Irish raw milk sample. Characterization of the(More)
AIMS To exploit the enterocin regulatory system for regulated expression of genes in Enterococcus. METHODS AND RESULTS Production of some pediocin-like bacteriocins such as enterocin A in Enterococcus is regulated by a three-component system comprising a histidine kinase (entK ), a response regulator (entR) and an induction factor (entF ). Exposure to the(More)
The nucleotide sequence of the plasmid-encoded LlaKR2I restriction-modification (R-M) system of Lactococcus lactis subsp. lactis biovar diacetylactis KR2 was determined. This R-M system comprises divergently transcribed endonuclease (llaKR2IR) and methyltransferase (llaKR2IM) genes; located in the intergenic region is a copy of the insertion element IS982,(More)
The nucleotide sequence of the chromosomally encoded type II ScrFI restriction/modification system from Lactococcus lactis subsp. cremoris UC503 was completed. The ScrFI restriction endonuclease (ENase) has previously been shown to specifically recognize 5' CCNGG 3' sites, cleaving after the second cytosine and the degenerate central base. The ENase gene(More)