Plasmids of lactococci – genetic accessories or genetic necessities?

Mills, Susan; McAuliffe, Olivia; Coffey, Aidan; Fitzgerald, Gerald F.; Ross, R. Paul

doi:10.1111/j.1574-6976.2005.00011.x

Cited by 85 publications

(121 citation statements)

References 315 publications

(392 reference statements)

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“…Plasmid content diversity of starter culture Dairy-associated lactococci are known to harbor a high number of plasmids (4-7) (Mills et al, 2006) that provide a crucial complement to starter culture functionality and appear to reflect the strain's adaptation to the dairy environment (Siezen et al, 2008). To determine whether plasmid diversity among isolates is independent of their genetic lineage assignment, the plasmid profiles of the starter culture isolates including 2-20 representatives of each genetic lineage (68 L. lactis and 17 Lc.…”

Section: Metabolic Complementation Of Lactococcus and Leuconostocmentioning

confidence: 99%

Multifactorial diversity sustains microbial community stability

et al. 2013

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Maintenance of a high degree of biodiversity in homogeneous environments is poorly understood. A complex cheese starter culture with a long history of use was characterized as a model system to study simple microbial communities. Eight distinct genetic lineages were identified, encompassing two species: Lactococcus lactis and Leuconostoc mesenteroides. The genetic lineages were found to be collections of strains with variable plasmid content and phage sensitivities. Kill-the-winner hypothesis explaining the suppression of the fittest strains by density-dependent phage predation was operational at the strain level. This prevents the eradication of entire genetic lineages from the community during propagation regimes (back-slopping), stabilizing the genetic heterogeneity in the starter culture against environmental uncertainty.

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Section: Metabolic Complementation Of Lactococcus and Leuconostocmentioning

confidence: 99%

Multifactorial diversity sustains microbial community stability

et al. 2013

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“…Industrial strains of L. lactis used for dairy fermentations often contain a complex complement of different plasmids (Gasson, 1983;Mills et al, 2006). Spontaneous rearrangements in the different plasmids made the assignment of phenotypes and the molecular analysis of gene transfer processes very difficult.…”

Section: Introductionmentioning

confidence: 99%

“…As technological and sensorial attributes are strain-dependent, it is therefore essential to increase knowledge about the diversity of strains, as it may contribute to particular technological properties and performance (Taïbi et al, 2010). Lactose utilization and casein breakdown are widely shared among the lactococcal plasmids, but more particular properties relevant to starter performance such as exopolysaccharide biosynthesis (van Kranenburg et al, 1999), phage resistance, bacteriocin production (Mills et al, 2006) and antibiotic resistance (Fló rez et al, 2008) have also been described as plasmidborne. Because of their industrial importance, the problems of plasmid instability and phenotype loss in lactococci have been extensively studied.…”

Section: Introductionmentioning

confidence: 99%

Molecular characterization and structural instability of the industrially important composite metabolic plasmid pLP712

et al. 2012

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The widely used plasmid-free Lactococcus lactis strain MG1363 was derived from the industrial dairy starter strain NCDO712. This strain carries a 55.39 kb plasmid encoding genes for lactose catabolism and a serine proteinase involved in casein degradation. We report the DNA sequencing and annotation of pLP712, which revealed additional metabolic genes, including peptidase F, D-lactate dehydrogenase and a-keto acid dehydrogenase (E3 complex). Comparison of pLP712 with other large lactococcal lactose and/or proteinase plasmids from L. lactis subsp. cremoris SK11 (pSK11L, pSK11P) and the plant strain L. lactis NCDO1867 (pGdh442) revealed their close relationship. The plasmid appears to have evolved through a series of genetic events as a composite of pGdh442, pSK11L and pSK11P. We describe in detail a scenario by which the metabolic genes relevant to the growth of its host in a milk environment have been unified on one replicon, reflecting the evolution of L. lactis as it changed its biological niche from plants to dairy environments. The extensive structural instability of pLP712 allows easy isolation of derivative plasmids lacking genes for casein degradation and/or lactose catabolism. Plasmid pLP712 is transferable by transduction and conjugation, and both of these processes result in significant molecular rearrangements. We report the detailed molecular analysis of insertion sequence element-mediated genetic rearrangements within pLP712 and several different mechanisms, including homologous recombination and adjacent deletion. Analysis of the integration of the lactose operon into the chromosome highlights the fluidity of the MG1363 integration hotspot and the potential for frequent movement of genes between plasmids and chromosomes in Lactococcus.

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“…Among listeria strains the highest sensitivity to nisin was determined in L. innocua Ln-03 strains and its MIC nisin was 2.5 mg nisin/l (100 IU nisin/ml). From literature it is known that Nis + lactococci contain genes in their genomes responsible for their immunity to nisin (Mills et al 2006).…”

Section: Resultsmentioning

confidence: 99%

Effect of Lactococcus sp. on the growth of Listeria sp. in the model UHT milk system

Šviráková¹,

Složilová²,

Tichovský³

et al. 2009

Czech J. Food Sci.

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Abstract:The work was aimed at the growth suppression of cultured listerias strains by cultured lactococci strains or commercial mesophilic cheese cultures during common cultivations in the model UHT milk system (0.5% w/w of milk fat content) at 30°C during 18 h aerobically. Milk was primarily fermented by lactococci at the level of 10 8 CFU/ml and secondarily contaminated by listerias at the level of 10 3 CFU/ml. The most intensive growth suppressions of both Listeria innocua (CCM 5884 or Ln-03) strains were caused by Lactococcus lactis subsp. lactis (LCC 416 or CHCC 2281) strains or DELVO-ADD ® 100-X DSF cheese culture; the listerias growth reductions was from the level of 10 3 CFU/ml to 10 0 CFU/ml. Obtained results should be applied to dairy industry provided that HACCP, GHP and GMP systems must be observed. Bacteria of Listeria genus attract an attention because of the health safety of final products, especially secondarily ripening cheeses, in the dairy industry of the Czech Republic and the European Union (EU). The majority of listerias species are harmless. L. monocytogenes (LM) species is pathogenic for human with 20% of death on listeriosis (Macela et al. 2006). L. ivanovii species is pathogenic just for sheep (Batt 2000). LM represents a facultative intracellular pathogen, which infects hosts by alimentary way (Schech 1983). Raw milk produced in milk farms represents a danger source of LM contamination as long as it is obtained during milking under GMP non-performance. In dairies raw milk is treated by heat with a guarantee LM inactivation. Final products can be secondarily contaminated by LM under conditions of sanitation regimes defaults or production control errors with the assistance of HACCP system. Listerias are able to reproduce at low storage temperatures and because of long incubation period of listeriosis it is difficult to prove whether a final product was contaminated at a producer or at a consumer only. For that reason naturally ways of listerias elimination are found. For example lactic acid bacteria can reduce or inhibit listerias and show rich biochemical activities. KeywordsThere are various products with antilisterial effect on the market of the Czech Republic and the EU. Listex TM P100 is a well-known and described commercial product that contains a virulent strictly lytic phage of P100 type, which shows a high specificity against LM (Carlton 2005).The aim of this work was to check a biochemical potential of lactococci for the reduction of listerias' growth in the model UHT milk system. Cultivation conditions of used strains. Lactococci and cheese cultures were cultivated in M17 broth with lactose (0.5% w/w) (LM17 broth) at 30°C for 18 h aerobically. Listerias were cultivated in BHI broth at 30°C for 18 h aerobically. All strains were also cultivated in UHT milk (0.5% w/w of milk fat content) with/ or without addition of yeast extract (YE) (0.5% w/w) at 30°C for 18 h aerobically. For work were used 1% (v/w) inocula. MATEriAlS And METHodS StrainsEstimation of lactococci and listerias...

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Plasmids of lactococci – genetic accessories or genetic necessities?

Cited by 85 publications

References 315 publications

Multifactorial diversity sustains microbial community stability

Multifactorial diversity sustains microbial community stability

Molecular characterization and structural instability of the industrially important composite metabolic plasmid pLP712

Effect of Lactococcus sp. on the growth of Listeria sp. in the model UHT milk system

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