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.

Persistence of Escherichia coli O157:H7 in Dairy Fermentation Systems

1998 ◽  
Vol 61 (12) ◽  
pp. 1602-1608 ◽  
Author(s):  
SEAN S. DINEEN ◽  
KAZUE TAKEUCHI ◽  
JANE E. SOUDAH ◽  
KATHRYN J. BOOR
Keyword(s):  
Escherichia Coli ◽  
Lactococcus Lactis ◽  
Dairy Products ◽  
Starter Cultures ◽  
Escherichia Coli O157 ◽  
Potential Health ◽  
E Coli ◽  
Lactococcus Lactis Subsp ◽  
Fermented Dairy Products ◽  
Fermented Dairy

We examined (i) the persistence of Escherichia coli O157:H7 as a postpasteurization contaminant in fermented dairy products; (ii) the ability of E. coli O157:H7 strains with and without the general stress regulatory protein, RpoS, to compete with commercial starter cultures in fermentation systems; and (iii) the survival of E. coli O157:H7 in the yogurt production process. In commercial products inoculated with 103 CFU/ml, E. coli O157:H7 was recovered for up to 12 days in yogurt (pH 4.0), 28 days in sour cream (pH 4.3), and at levels >102 CFU/ml at 35 days in buttermilk (pH 4.1). For the starter culture competition trials, the relative inhibition of E. coli O157:H7 in the experimental fermentation systems was, in decreasing order, thermophilic culture mixture, Lactobacillus delbrueckii subsp. bulgaricus R110 alone, Lactococcus lactis subsp. lactis D280 alone, Lactococcus lactis subsp. cremoris D62 alone, and Streptococcus thermophilus C90 alone showing the least inhibition. Recovery of the rpoS mutant was lower than recovery of its wild-type parent by 72 h or earlier in the presence of individual starter cultures. No E. coli O157:H7 were recovered after the curd formation step in yogurt manufactured with milk inoculated with 105 CFU/ml. Our results show that (i) postprocessing entry of E. coli O157:H7 into fermented dairy products represents a potential health hazard; (ii) commercial starter cultures differ in their ability to reduce E. coli O157:H7 CFU numbers in fermentation systems; and (iii) the RpoS protein appears to most effectively contribute to bacterial survival in the presence of conditions that are moderately lethal to the cell.

scholarly journals The Tape Measure Protein Is Involved in the Heat Stability ofLactococcus lactisPhages

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Hany Geagea ◽  
Simon J. Labrie ◽  
Muriel Subirade ◽  
Sylvain Moineau
Keyword(s):  
Lactococcus Lactis ◽  
Control Strategies ◽  
Heat Stability ◽  
Genetic Determinant ◽  
Tape Measure Protein ◽  
Content Type ◽  
Milk Fermentation ◽  
Gene Coding ◽  
Fermented Dairy Products ◽  
Fermented Dairy

ABSTRACTVirulent lactococcal phages are still a major risk for milk fermentation processes as they may lead to slowdowns and low-quality fermented dairy products, particularly cheeses. Some of the phage control strategies used by the industry rely on heat treatments. Recently, a fewLactococcus lactisphages were found to be highly thermo-resistant. To identify the genetic determinant(s) responsible for the thermal resistance of lactococcal phages, we used the virulent phage CB14 (of theLactococcus lactis936 [nowSk1virus] phage group) to select for phage mutants with increased heat stability. By treating phage CB14 to successive low and high temperatures, we were able to select two CB14 derivatives with increased heat stability. Sequencing of their genome revealed the same nucleotide sequences as the wild-type phage CB14, except for a same-sized deletion (120 bp) in the gene coding for the tape measure protein (TMP) of each phage mutant, but at a different position. The TMP protein sequences of these mutant phages were compared with their homologues in other wild-typeL. lactisphages with a wide diversity in heat stability. Comparative analysis showed that the same nucleotide deletion appears to have also occurred in the gene coding for the TMP of highly thermo-resistant lactococcal phages P1532 and P680. We propose that the TMP is, in part, responsible for the heat stability of the highly predominant lactococcal phages of theSk1virusgroup.IMPORTANCEVirulent lactococcal phages still represent a major risk for milk fermentation as they may lead to slowdowns and low-quality fermented dairy products. Heat treatment is one of the most commonly used methods to control these virulent phages in cheese by-products. Recently, a fewLactococcus lactisphages, members of theSk1virusgroup, have emerged with high thermal stability. To our knowledge, the genetic determinant(s) responsible for this thermal resistance in lactococcal phages is unknown. A better understanding of the thermal stability of these emerging virulent lactococcal phages is needed to improve industrial control strategies. In this work, we report the identification of a phage structural protein that is involved in the heat stability of a virulentSk1virusphage. Identifying such a genetic determinant for heat stability is a first step in understanding the emergence of this group of thermostable phages.

scholarly journals Draft Genome Sequences of Four Lactococcus lactis Strains Isolated from Diverse Niches, Including Dairy Products, Grass, and Green Peas

2019 ◽  
Vol 8 (35) ◽  
Author(s):  
Desirée Roman Naranjo ◽  
Michael Callanan ◽  
Olivia McAuliffe
Keyword(s):  
Lactococcus Lactis ◽  
Dairy Products ◽  
Draft Genome ◽  
Genome Sequences ◽  
Content Type ◽  
Fermented Dairy Products ◽  
Fermented Dairy ◽  
Green Peas

Lactococcus lactis has been used for millennia as a starter organism in the production of many fermented dairy products. This announcement includes the draft genome sequences of four strains of Lactococcus lactis, two of dairy origin and two from nondairy sources.

scholarly journals Physiological and biochemical characteristics of the Lactococcus lactis strains isolated from natural sources

2019 ◽  
Vol 64 (3) ◽  
pp. 268-276
Author(s):  
M. E. Safonova ◽  
I. A. Naidenko ◽  
A. I. Buko
Keyword(s):  
Lactococcus Lactis ◽  
Biochemical Properties ◽  
Starter Cultures ◽  
Bacterial Strains ◽  
Natural Sources ◽  
Physiological And Biochemical Characteristics ◽  
Fermented Dairy Products ◽  
Fermented Dairy ◽  
Physiological And Biochemical ◽  
Physiological And Biochemical Properties

The data have been presented on physiological and biochemical properties (growth, acidogenic, proteolytic and antagonistic аctivity, resistance to NaCl) of lactic acid bacterial strains of Lactococcus lactis isolated from Belarus natural sources. These strains are promising for use as starter cultures for fermented dairy products, cheese.

scholarly journals Draft Genome Sequences of 24 Lactococcus lactis Strains

2017 ◽  
Vol 5 (13) ◽  
Author(s):  
Lennart Backus ◽  
Michiel Wels ◽  
Jos Boekhorst ◽  
Annereinou R. Dijkstra ◽  
Marke Beerthuyzen ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacterium ◽  
Lactococcus Lactis ◽  
Dairy Products ◽  
Draft Genome ◽  
Genome Sequences ◽  
Geographic Locations ◽  
Content Type ◽  
Fermented Dairy Products ◽  
Fermented Dairy

ABSTRACT The lactic acid bacterium Lactococcus lactis is widely used for the production of fermented dairy products. Here, we present the draft genome sequences of 24 L. lactis strains isolated from different environments and geographic locations.

Evaluating the technological properties of lactic acid bacteria in Wagyu cattle milk

2021 ◽  
pp. 1-7
Author(s):  
Harutoshi Tsuda ◽  
Kana Kodama
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Raw Milk ◽  
Starter Cultures ◽  
Technological Properties ◽  
Mature Milk ◽  
16S Rdna Sequence Analysis ◽  
Physiological And Biochemical Characteristics ◽  
Fermented Dairy Products ◽  
Fermented Dairy

Abstract This paper reveals the technological properties of lactic acid bacteria isolated from raw milk (colostrum and mature milk) of Wagyu cattle raised in Okayama Prefecture, Japan. Isolates were identified based on their physiological and biochemical characteristics as well as 16S rDNA sequence analysis. Streptococcus lutetiensis and Lactobacillus plantarum showed high acid and diacetyl-acetoin production in milk after 24 h of incubation at 40 and 30°C, respectively. These strains are thought to have potential for use as starter cultures and adjunct cultures for fermented dairy products.

scholarly journals Inclusion of Probiotics into Fermented Buffalo (Bubalus bubalis) Milk: An Overview of Challenges and Opportunities

Fermentation ◽  
2020 ◽  
Vol 6 (4) ◽  
pp. 121
Author(s):  
A.M.N.L. Abesinghe ◽  
Hasitha Priyashantha ◽  
P.H.P. Prasanna ◽  
Maheshika S. Kurukulasuriya ◽  
C.S. Ranadheera ◽  
...  
Keyword(s):  
Dairy Products ◽  
Health Benefits ◽  
Natural Antioxidants ◽  
Storage Conditions ◽  
Bubalus Bubalis ◽  
Buffalo Milk ◽  
Starter Cultures ◽  
Fermented Dairy Products ◽  
Calcium Iron ◽  
Fermented Dairy

Buffalo-milk-based dairy products provide various health benefits to humans since buffalo milk serves as a rich source of protein, fat, lactose, calcium, iron, phosphorus, vitamin A and natural antioxidants. Dairy products such as Meekiri, Dadih, Dadi and Lassie, which are derived from Artisanal fermentation of buffalo milk, have been consumed for many years. Probiotic potentials of indigenous microflora in fermented buffalo milk have been well documented. Incorporation of certain probiotics into the buffalo-milk-based dairy products conferred vital health benefits to the consumers, although is not a common practice. However, several challenges are associated with incorporating probiotics into buffalo-milk-based dairy products. The viability of probiotic bacteria can be reduced due to processing and environmental stress during storage. Further, incompatibility of probiotics with traditional starter cultures and high acidity of fermented dairy products may lead to poor viability of probiotics. The weak acidifying performance of probiotics may affect the organoleptic quality of fermented dairy products. Besides these challenges, several innovative technologies such as the use of microencapsulated probiotics, ultrasonication, the inclusion of prebiotics, use of appropriate packaging and optimal storage conditions have been reported, promising stability and viability of probiotics in buffalo-milk-based fermented dairy products.

scholarly journals Modeling of rheological characteristics of the fermented dairy products obtained by novel and traditional starter cultures

2018 ◽  
Vol 55 (6) ◽  
pp. 2180-2188 ◽  
Author(s):  
Dajana V. Vukić ◽  
Vladimir R. Vukić ◽  
Spasenija D. Milanović ◽  
Mirela D. Ilicić ◽  
Katarina G. Kanurić
Keyword(s):  
Dairy Products ◽  
Starter Cultures ◽  
Rheological Characteristics ◽  
Fermented Dairy Products ◽  
Fermented Dairy

scholarly journals Unleashing Natural Competence in Lactococcus lactis by Induction of the Competence Regulator ComX

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Joyce Mulder ◽  
Michiel Wels ◽  
Oscar P. Kuipers ◽  
Michiel Kleerebezem ◽  
Peter A. Bron
Keyword(s):  
Lactococcus Lactis ◽  
Genetic Manipulation ◽  
Bacterial Species ◽  
Streptococcus Thermophilus ◽  
Starter Cultures ◽  
Natural Competence ◽  
Content Type ◽  
Competence Gene ◽  
Gene Sets ◽  
Novel Traits

ABSTRACT In biotechnological workhorses like Streptococcus thermophilus and Bacillus subtilis, natural competence can be induced, which facilitates genetic manipulation of these microbes. However, in strains of the important dairy starter Lactococcus lactis, natural competence has not been established to date. However, in silico analysis of the complete genome sequences of 43 L. lactis strains revealed complete late competence gene sets in 2 L. lactis subsp. cremoris strains (KW2 and KW10) and at least 10 L. lactis subsp. lactis strains, including the model strain IL1403 and the plant-derived strain KF147. The remainder of the strains, including all dairy isolates, displayed genomic decay in one or more of the late competence genes. Nisin-controlled expression of the competence regulator comX in L. lactis subsp. lactis KF147 resulted in the induction of expression of the canonical competence regulon and elicited a state of natural competence in this strain. In contrast, comX expression in L. lactis NZ9000, which was predicted to encode an incomplete competence gene set, failed to induce natural competence. Moreover, mutagenesis of the comEA-EC operon in strain KF147 abolished the comX-driven natural competence, underlining the involvement of the competence machinery. Finally, introduction of nisin-inducible comX expression into nisRK-harboring derivatives of strains IL1403 and KW2 allowed the induction of natural competence in these strains also, expanding this phenotype to other L. lactis strains of both subspecies. IMPORTANCE Specific bacterial species are able to enter a state of natural competence in which DNA is taken up from the environment, allowing the introduction of novel traits. Strains of the species Lactococcus lactis are very important starter cultures for the fermentation of milk in the cheese production process, where these bacteria contribute to the flavor and texture of the end product. The activation of natural competence in this industrially relevant organism can accelerate research aiming to understand industrially relevant traits of these bacteria and can facilitate engineering strategies to harness the natural biodiversity of the species in optimized starter strains.

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