Relevant bibliographies by topics / Lactococcus lactis subsp. cremoris

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Academic literature on the topic 'Lactococcus lactis subsp. cremoris'

Author: Grafiati
Published: 4 June 2021
Last updated: 13 February 2022

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Journal articles on the topic "Lactococcus lactis subsp. cremoris"

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Kauser-Ul-Alam, Md, Yu Toba, Shoji Hioki, Toru Hayakawa, Haruto Kumura, and Jun-ichi Wakamatsu. "Lactococcus lactis subsp. cremoris Produces Zinc Protoporphyrin IX Both Aerobically and Anaerobically and Improves the Bright Red Color of Fermented Meat Products." Foods 9, no. 11 (2020): 1583. http://dx.doi.org/10.3390/foods9111583.

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This study assessed the color improvement via zinc protoporphyrin IX (ZnPP) formation in nitrite-free, dry-cured sausages processed using five varieties of ZnPP-forming lactic acid bacteria (LAB). The ZnPP contents and color intensity of the sausages and other technological properties were analyzed during the processing of sausages. LAB count and acidity significantly increased in the LAB-inoculated sausages compared to the control group. The bright red color was observed both inside and outside the sausages inoculated with Lactococcus lactis subsp. cremoris and Leuconostoc lactis. However, a brown color was observed on the surface of the sausage inoculated with Lactobacillus spp. The redness of Lactococcus lactis subsp. cremoris-inoculated sausages was close to that of the nitrite-added group. Moreover, the external bright red color was improved by Lactococcus lactis subsp. cremoris due to the aerobic formation of ZnPP. Therefore, Lactococcus lactis subsp. cremoris can be used to improve the color of fermented meat products.
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CENTENO, JUAN A., PILAR GAYA, MARGARITA MEDINA, and MANUEL NUÑEZ. "Cross-Inhibition among Wild Strains of Lactococcus lactis Isolated from the Same Ecological Niche." Journal of Food Protection 65, no. 1 (2002): 205–10. http://dx.doi.org/10.4315/0362-028x-65.1.205.

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The cross-inhibition between 23 Lactococcus lactis subsp. lactis strains and 9 L. lactis subsp. cremoris strains with different randomly amplified polymorphic DNA patterns, all isolated from the same ecological niche—cheese made in the spring at a single factory from raw milk without added lactic starter cultures—was investigated. Cross-inhibition, as determined by the agar well diffusion assay, was recorded in 130 cases (12.7%) out of 1,024 total cases, with 109 cases due to supernatants of L. lactis subsp. lactis strains and 21 cases due to supernatants of L. lactis subsp. cremoris strains. L. lactis strains isolated in April, May, and June showed differences in their inhibitory activities, with cross-inhibition against each other in 34.7, 14.1, and 6.1% of the cases, respectively. Polymerase chain reaction techniques using specific primers for nisin, lacticin 481, and lactococcin A only revealed the presence of the structural gene of lacticin 481 in two L. lactis subsp. lactis strains.
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Terzic-Vidojevic, Amarela, Sanja Mihajlovic, Gordana Uzelac, et al. "Identification and characterization of lactic acid bacteria isolated from artisanal white brined Golija cows’ milk cheeses." Archives of Biological Sciences 66, no. 1 (2014): 179–92. http://dx.doi.org/10.2298/abs1401179t.

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The aim of this study was to identify and characterize the lactic acid bacteria (LAB) of artisanal Golija raw and cooked cows? milk cheeses traditionally manufactured without the addition of starter culture. A total of 188 Gram-positive and catalase-negative isolates of Golija cheeses were obtained from seven samples of different ripening time. Phenotypebased assays as well as rep-PCR and 16S rDNA sequence analysis were undertaken for all 188 Lstrains. The most diverse species were isolated from 20-day-old BGGO8 cheese (Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus casei/paracasei, Lactobacillus sucicola, Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. lactis bv. diacetylactis, Enterococcus faecium, Enterococcus durans and Leuconostoc mesenteroides). In other Golija cheeses Lactobacillus reuteri, Lactobacillus curvatus, Lactobacillus rhamnosus, Lactococcus lactis subsp. cremoris, Lactococcus garvieae, Streptococcus thermophilus and Leuconostoc pseudomesenteroides were found. Pronounced antimicrobial properties showed enterococci (13/42) and lactococci (12/31), while the good proteolytic activity demonstrated lactococci (13/31) and lactobacilli (10/29).
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MEDINA, ROXANA, MARTA KATZ, SILVIA GONZALEZ, and GUILLERMO OLIVER. "Characterization of the Lactic Acid Bacteria in Ewe's Milk and Cheese from Northwest Argentina." Journal of Food Protection 64, no. 4 (2001): 559–63. http://dx.doi.org/10.4315/0362-028x-64.4.559.

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Indigenous lactic acid bacteria in ewe's milk and artisanal cheese were studied in four samples of fresh raw milk and four 1-month-old cheeses from the provinces of northwest Argentina. Mean growth counts on M17, MRS, and MSE agar media did not show significant differences (P < 0.05) in raw milk and cheeses. Isolates of lactic acid bacteria from milk were identified as Enterococcus (48%), lactococci (14%), leuconostocs (8%), and lactobacilli (30%). All lactococci were identified as Lactococcus lactis (subsp. lactis and subsp. cremoris). Lactobacilli were identified as Lactobacillus plantarum (92%) and Lactobacillus acidophilus (8%). Enterococci (59%) and lactobacilli (41%) were isolated from cheeses. L. plantarum (93%), L. acidophilus (5%), and Lactobacillus casei (2%) were most frequently isolated. L. lactis subsp. lactis biovar diacetylactis strains were considered as fast acid producers. L. lactis subsp. cremoris strains were slow acid producers. L. plantarum and L. casei strains identified from the cheeses showed slow acid production. The majority of the lactobacilli and Lactococcus lactis strains utilized citrate and produced diacetyl and acetoin in milk. Enzyme activities (API-ZYM tests) of lactococci were low, but activities of L. plantarum strains were considerably higher. The predominance of L. plantarum in artisanal cheese is probably important in the ripening of these cheeses due to their physiological and biochemical characteristics.
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Pérez, Tania, José Luis Balcázar, Alvaro Peix, et al. "Lactococcus lactis subsp. tructae subsp. nov. isolated from the intestinal mucus of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss)." International Journal of Systematic and Evolutionary Microbiology 61, no. 8 (2011): 1894–98. http://dx.doi.org/10.1099/ijs.0.023945-0.

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The species Lactococcus lactis currently includes three subspecies; L. lactis subsp. lactis and L. lactis subsp. cremoris, isolated from milk sources, and L. lactis subsp. hordniae, isolated from the leafhopper Hordnia circellata. In this study, three strains, designated L105T, I3 and L101, were isolated from the intestinal mucus of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss). These strains were closely related to members of the species Lactococcus lactis. Strain L105T showed 99.4 % 16S rRNA gene sequence similarity to that of the type strains L. lactis subsp. lactis NCDO 604T and L. lactis subsp. hordniae NCDO 2181T and showed 99.9 % similarity to the type strain Lactococcus lactis subsp. cremoris NCDO 607T. Analysis of two housekeeping genes, rpoB and recA, confirmed the close relationship between the novel strains and L. lactis subsp. cremoris with similarities of 99.3 and 99.7 %, respectively. The three strains could, however, be differentiated from their closest relatives on the basis of several phenotypic characteristics, as was the case for L. lactis subsp. lactis and L. lactis subsp. hordniae, which were also closely related on the basis of 16S rRNA, rpoB and recA gene sequence similarities. The strains isolated in this study represent a new subspecies, for which the name Lactococcus lactis subsp. tructae subsp. nov. is proposed. The type strain is L105T ( = LMG 24662T = DSM 21502T).
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Stachelska, Milena Alicja. "Quantitative assessment of Lactococcus lactis subsp. cremoris present in artisanal raw cow’s milk cheese." Acta Veterinaria Brno 87, no. 2 (2018): 189–95. http://dx.doi.org/10.2754/avb201887020189.

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Lactococcus lactis subsp. cremoris belongs to lactic acid bacteria that play a crucial role in cheese production and it is known to be beneficial to human health. The aim of the study was to establish a rapid and accurate quantitative real-time polymerase chain reaction (qPCR) method to detect and enumerate L. lactis subsp. cremoris in artisanal raw cow’s milk cheese. Artisanal raw cow’s milk cheese samples were used to check for presence and number of L. lactis subsp. cremoris strains. The method applies a set of target-specific PCR (polymerase chain reaction) primers and a fluorogenic probe, and amplifies a part of the LACR_RS01280 gene that encodes the aminoacetone oxidase family flavin adenine dinucleotide (FAD) binding enzyme. All 5 L. lactis subsp. cremoris strains examined were found to be qPCR positive. There was no signal recorded for 8 strains which belong to closely related species. The limit of detection amounted to ten copies per reaction and the assay indicated a linear dynamic range of seven logs. This method may be applied in detection and enumeration of L. lactis subsp. cremoris in cheese during its ripening. Moreover, it may be applied to examine the distribution of L. lactis subsp. cremoris during the cheese production and ripening.
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Bolotin, Alexander, Benoit Quinquis, Alexei Sorokin, and Dusko S. Ehrlich. "Recent Genetic Transfer between Lactococcus lactis and Enterobacteria." Journal of Bacteriology 186, no. 19 (2004): 6671–77. http://dx.doi.org/10.1128/jb.186.19.6671-6677.2004.

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ABSTRACT The genome sequence of Lactococcus lactis revealed that the ycdB gene was recently exchanged between lactococci and enterobacteria. The present study of ycdB orthologs suggests that L. lactis was probably the gene donor and reveals three instances of gene transfer to enterobacteria. Analysis of ycdB gene transfer between two L. lactis subspecies, L. lactis subsp. lactis and L. lactis subsp. cremoris, indicates that the gene can be mobilized, possibly by conjugation.
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Wegmann, Udo, Mary O'Connell-Motherway, Aldert Zomer, et al. "Complete Genome Sequence of the Prototype Lactic Acid Bacterium Lactococcus lactis subsp. cremoris MG1363." Journal of Bacteriology 189, no. 8 (2007): 3256–70. http://dx.doi.org/10.1128/jb.01768-06.

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ABSTRACT Lactococcus lactis is of great importance for the nutrition of hundreds of millions of people worldwide. This paper describes the genome sequence of Lactococcus lactis subsp. cremoris MG1363, the lactococcal strain most intensively studied throughout the world. The 2,529,478-bp genome contains 81 pseudogenes and encodes 2,436 proteins. Of the 530 unique proteins, 47 belong to the COG (clusters of orthologous groups) functional category “carbohydrate metabolism and transport,” by far the largest category of novel proteins in comparison with L. lactis subsp. lactis IL1403. Nearly one-fifth of the 71 insertion elements are concentrated in a specific 56-kb region. This integration hot-spot region carries genes that are typically associated with lactococcal plasmids and a repeat sequence specifically found on plasmids and in the “lateral gene transfer hot spot” in the genome of Streptococcus thermophilus. Although the parent of L. lactis MG1363 was used to demonstrate lysogeny in Lactococcus, L. lactis MG1363 carries four remnant/satellite phages and two apparently complete prophages. The availability of the L. lactis MG1363 genome sequence will reinforce its status as the prototype among lactic acid bacteria through facilitation of further applied and fundamental research.
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Larisch, B. C., D. Poncelet, C. P. Champagne, and R. J. Neufeld. "Microencapsulation of Lactococcus lactis subsp. cremoris." Journal of Microencapsulation 11, no. 2 (1994): 189–95. http://dx.doi.org/10.3109/02652049409040450.

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REDDY, K. ANJAN, and ELMER H. MARTH. "Lactic Acid Bacteria in Cheddar Cheese Made with Sodium Chloride, Potassium Chloride or Mixtures of the Two Salts." Journal of Food Protection 58, no. 1 (1995): 62–69. http://dx.doi.org/10.4315/0362-028x-58.1.62.

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Three different split lots of Cheddar cheese curd were prepared with added sodium chloride (NaCl) potassium chloride (KCl) or mixtures of NaCl/KCl (2:1 1:1 1:2 and 3:4 all on wt/wt basis) to achieve a final salt concentration of 1.5 or 1.75%. At intervals during ripening at 3±1°C samples were plated with All-Purpose Tween (APT) and Lactobacillus Selection (LBS) agar. Isolates were obtained of bacteria that predominated on the agar media. In the first trial (Lactococcus lactis subsp. lactis plus L. lactis subsp. cremoris served as starter cultures) L. lactis subsp.lactis Lactobacillus casei and other lactobacilli were the predominant bacteria regardless of the salting treatment Received by the cheese. In the second trial (L. lactis subsp. lactis served as the starter culture) unclassified lactococci L. lactis subsp. lactis unclassified lactobacilli and L. casei predominated regardless of the salting treatment given the cheese. In the third trial (L. lactis subsp. cremoris served as the starter culture) unclassified lactococci unclassified lactobacilli L. casei and Pediococcus cerevisiae predominated regardless of the salting treatment applied to the cheese Thus use of KCl to replace some of the NaCl for salting cheese had no detectable effect on the kinds of lactic acid bacteria that developed in ripening Cheddar cheese.
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Dissertations / Theses on the topic "Lactococcus lactis subsp. cremoris"

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Barrena, Gonzalez Célia. "Étude de deux bactériocines produites par Lactococcus lactis subsp. Cremoris et Lactococcus lactis subsp. Lactis." Nancy 1, 1996. http://www.theses.fr/1996NAN10002.

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Les bactériocines J46 et H possèdent un spectre d'action relativement large en incluant des bactéries telles que c. Tyrobutyricum. Ces bactéries sont thermostables et tolèrent des pH de 3 à 9, elles sont détruites par des enzymes protéolytiques. Les conditions optimales pour la production de la bactériocine J46 sont : un pH de 5,5 ; une température de 30c et le milieu de culture CGB, cette production étant encore améliorée par la présence de Tween 80. La souche l. Lactis subsp. Lactis H, elle, est capable de produire sa bactériocine en l'absence de lactose. La bactériocine j46 purifiée est une protéine de 3kDa et la bactériocine H semi-purifiée à un poids moléculaire compris entre 6 et 10 kDa. La bactériocine J46 est adsorbée sur les cellules cibles en phase logarithmique de croissance, qui ont une membrane énergisée ; elle provoque la perte de K+ et l'hydrolyse de l'ATP interne. La séquence de la région N-terminale est: Lys-Gly-Gly-Ser-Val-Ile-His-X-Ile-X-His (X étant des résidus identifiés). Le gène structural de la bactériocine J46 est localisé dans un plasmide de 60 kb ; cette bactériocine est synthétisée sous forme d'un peptide précurseur de 51 acides amines avec une extension N-terminale de 24 résidus. Le gène structural de la bactériocine H a été amplifie par PCR, clone et séquence ; l'analyse de sa séquence montre qu'il a une homologie de 100% avec celle de la nisine A
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Hyndman, Caroline Louise. "Immobilization of lactococcus lactis subsp. cremoris within cross- linked protein microcapsules." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22443.

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Lactococcus lactis subspecies cremoris was encapsulated by cross-linking emulsified gelatin at an oil/water interface. The organic phase in the emulsion step consisted of nontoxic vegetable or silicone oil and the exposure of the cells to cross-linking agent was minimized in two ways. The concentration of tolylene-2,4-diisocyanate was reduced to 34 mM and a lower viscosity oil was used as the continuous phase in the emulsion step so as to decrease the specific surface area of the microcapsules. Viable cell count (cfu/ml milk) was estimated to be reduced by five orders of magnitude for microcapsules formed in sunflower seed oil while a reduction of only two orders of magnitude resulted from the encapsulation process when using the lower viscosity silicone oil. Growth within the microcapsules occurred during fermentation and activity of the encapsulated cells increased when the microcapsules were used in subsequent assays. In the third sequential activity assay for cells encapsulated using silicone oil the time to reduce the pH of milk to 5.5 was 2.8 hours and the estimated initial intracapsular cell density was 10$ sp9$ cfu/g microcapsules.
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Larisch, Belinda C. "Microencapsulation of lactococcus lactis subsp. cremoris for application in the dairy industry." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60061.

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Microcapsules are comprised of particles or droplets surrounded by ultrathin polymeric membranes. The process of microencapsulation is currently used in the immobilization of biocatalysts, including enzymes and biological cells. A study of the possible use of encapsulated lactic acid bacteria in the dairy industry was performed for the purpose of comparing three methods of immobilizing Lactococcus lactis subsp. cremoris. A new immobilization method involving microencapsulation of L. lactis subsp. cremoris within a cross-linked polyethyleneimine membrane was developed. This technique was compared to existing alginate bead and nylon membrane microcapsule immobilization in terms of the microorganism viability and lactic acid production activity. The alginate bead, surrounded by a poly-L-lysine membrane, afforded the greatest viability and activity of the encapsulated cells. The nylon encapsulation procedure did not result in the maintenance of viable cells, and the polyethyleneimine encapsulation procedure did not provide evidence of lactic acid production by the cells.<br>The rate of lactic acid production by Lactococcus lactis subsp. cremoris encapsulated in alginate-PLL is less than that produced by unencapsulated or free cells. The difference diminishes with increasing cell concentrations. At a concentration of approximately 10$ sp9$ cells/ml of milk, the time required to acidify the milk to the point at which it is useful in the dairy industry is identical for both free and encapsulated cells.
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Huot, Emmanuel. "Propriétés d'une nouvelle bactériocine produite par Lactococcus lactis subsp. Cremoris J46 : étude du mode d'action." Nancy 1, 1995. http://www.theses.fr/1995NAN10360.

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Les recherches entreprises nous ont permis d'isoler deux lactocoques producteurs de bactériocines : Lactococcus lactis subp. Cremoris J46 et L. Lactis subsp. Lactis h. La bactériocine J46 présente un large spectre d'activité bactéricide dont la première étape semble être une adsorption spécifique aux bactéries sensibles. De plus, nous avons démontré l'importance cruciale de l'état physiologique de la cellule cible sur sa sensibilité a la bactériocine: inefficace sur des cellules de L. Lactis subsp. Cremoris SC11 se développant a des taux de croissance inferieurs à 0,6 h-1 ; la bactériocine J46 provoque la perte du potassium, la dissipation du pool intracellulaire en ATP et pour finir la mort cellulaire sans lyse de ces mêmes cellules prélevées a un taux de croissance supérieur à 0,6h-1. Des expériences d'optimisation de production ont été conduites. Nous avons ainsi pu démontrer le rôle fondamentale joué par le tween 80 : ce dernier supprime l'adhésion de la bactériocine à la cellule productrice et en stimule la production. Les études génétiques entreprises nous ont permis de montre que : les gènes de biosynthèse et d'immunité de la bactériocine J46 sont portés par un plasmide de 60-kb. Le gène de structure de cette bactériocine a été cloné et séquencé. La bactériocine h s'est révélée après amplification par PCR, clonage et séquençage du gène de structure, identique à 100% à la nisine A. Cependant, les différences reproductibles au niveau du spectre d'activité, de la sensibilité à diverses protéases ou de la thermorésistance avaient pu être notées entre la nisine a et la bactériocine H lors de l'étude préliminaire. Il semble donc que certains composés produits lors du processus fermentaire peuvent interférer avec la détermination des propriétés biochimiques de la nisine
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Stien, Gilles. "Mise en oeuvre de Lactococcus Lactis subsp. Lactis Biovar. Diacetylactis et de Leuconostoc Mesenteroides subsp. Cremoris en cultures pures et en co-cultures : études cinétiques et suivi en ligne de l'influence de l'acide citrique et du pH sur le comportement métabolique." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL107N.

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L’objectif de cette thèse est d’analyser, de comprendre et de quantifier l’action que peuvent exercer différents paramètres opératoires d’un procédé sur le comportement métabolique et les cinétiques de croissance et de production de molécules aromatisantes de deux bactéries lactiques mésophiles : Lactococcus lactis subsp. Lactis biovar. Diacetylactis et Leuconostoc mesenteroides subsp. Cremoris. La première partie de cette étude est consacrée à la mise au point et à la validation des outils destinés à la mesure, hors et en ligne, d’une dizaine de composés différents. Elle a abouti à la mise en place d’un échantillonneur de molécules à l’état de vapeur pour la détection, en ligne, des molécules volatiles et à l’utilisation d’un échantillonneur de liquide de fermentation filtré pour la détection en ligne des autres composés. La seconde partie a permis de mettre en évidence et de quantifier, au moyen de cultures pures discontinues, l’influence du pH sur les métabolismes et les cinétiques des deux bactéries et l’importance du rôle de l’acide citrique au sein du métabolisme des deux espèces. La troisième partie est consacrée à la mise en œuvre des deux types de bactérie en co-cultures à différents pH régulés et à l’analyse des cinétiques observées<br>The aim of this thesis is to analyse, to understand and to quantify the influence of operating conditions on metabolic behavior, on growth kinetics and on aromatic compounds production kinetics of two mesophilic lactic acid bacteria : Lactococcus lactis subsp. Lactis biovar. Diacetylactis and Leuconostoc mesentieroides subsp. Cremoris. The first part of this work deals with the perfecting and the validation of original analytical methods used for on-line and out-line monitoring of about tend different compounds. This part leads to the utilization of a membrane gas sensor for the on-line volatile compound analysis and of a steile liquid auto-sampler for the on-line detection of other compounds. In a second part, studies in pure cultures led to show and to quantify pH influence on kinetics and metabolisms of bacteria and to specify the importance of the role of citric acid in general metabolism of the two studied species. The third part deals with the use of the two types of bacteria in mixed cultures at different pH values and analyse the kinetic results
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Cefalo, Angela D. "Characterization of the Function and Interaction of Proteins Involved in Exopolysaccharide Synthesis in Streptococcus thermophilus, Streptococcus iniae, and Lactococcus lactis subsp. cremoris." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1424.

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Amino acid residues that are important for metal binding and catalysis in Grampositive phosphotyrosine phosphatases were identified in Streptococcus thermophilus Wzh/EpsB proteins. The Wzh protein from S. thermophilus MR-1C was purified after heterologous expression and tested for phosphatase activity against synthetic phosphotyrosine and phosphoserine/threonine peptides. The purified Wzh protein was able to remove phosphate from both phosphotyrosine peptides tested and the phosphatase activity of Wzh was dramatically reduced by the presence of the phosphotyrosine phosphatase inhibitor sodium vanadate at concentrations of 1, 5, and 10 mM. Purified Wzh had no activity against the synthetic phosphoserine/threonine peptide. These results established that Wzh functions as a phosphotyrosine phosphatase. By using the yeast two-hybrid system, strong intraspecific protein interactions were detected in S. thermophilus MR-1C, Streptococcus iniae 9066, and Lactococcus lactis subsp. cremoris JRF1 between the putative transmembrane activation protein (Wzd, CpsC, and EpsA, respectively) and the putative protein tyrosine kinase (Wze, CpsD, and EpsB, respectively). Weaker protein interactions take place forming a dimer between two identical protein tyrosine kinases and between the protein tyrosine kinase and phosphotyrosine phosphatase (Wzh, CpsB, and EpsC, respectively) in these species. Protein-protein interactions involving a S. thermophilus MR-1C Wzd/Wze fusion protein and Wzd and Wze indicated that these proteins may form multi-protein complexes. All combinations of the S. thermophilus Wzh, Wzd, Wze, Wzg (regulation), CpsE (glycosyl-1-phosphate transferase), CpsS (polymerization), CpsL (unknown), CpsW (regulation), and CpsU (membrane translocation) proteins were analyzed for protein-protein interactions but no additional interactions were discovered. For each of the intraspecific interactions detected, interspecific interactions were also detected when one protein was from S. iniae and the other was from S. thermophilus. Interactions were also observed between two protein tyrosine kinases when one protein was from either of the Streptococcus species and the other from L. lactis subsp. cremoris. These results and sequence comparisons performed in this study support the conclusion that interactions among the components of the tyrosine kinase/phosphatase regulatory system are conserved in the family Streptococcaceae. Interspecific protein-protein interactions suggest that functional regulatory complexes can be formed in naturally occurring and genetically engineered recombinant strains.
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Meghrous, Djamel. "Isolement, caractérisation et purification de bactériocines produites par des bactéries lactiques : études physiologiques et biochimiques." Nancy 1, 1993. http://www.theses.fr/1993NAN10197.

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La production de substances antibactériennes telles que les bactériocines par des bactéries gras (generaly recognized as safe) en général et par des bactéries lactiques en particulier représente une voie intéressante pour lutter contre les micro-organismes pathogènes et indésirables. Dans cette optique, nous avons isolé deux lactocoques producteurs de bactériocines: lactococcus cremoris et lactococcus lactis, espèces largement utilisées dans l'industrie alimentaire. La bactériocine de lactococcus cremoris est la plus performante qui ait été isolée chez cette espèce; son spectre d'action, sa thermostabilité et sa stabilité aux ph proches de la neutralité donnent à cette protéine la potentialité de complémenter l'action antibactérienne de la nisine. Le déterminant génétique est de nature plasmidique. En conditions de croissance microbienne défavorable, la production diminue selon la nature de l'élément limitant. La production de la nisine a été étudiée en chemostat et les vitesses spécifiques de biosynthèse parfaitement définies grâce aux cultures continues qui ont été mises à profit pour réaliser des études sur la production de nisine par les cellules non proliferantes.
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To, Thi Mai Huong. "Modification de la composition lipidique membranaire chez les bactéries lactiques en conditions de stress : étude du rôle physiologique des Acides Gras Cycliques chez deux modèles : oenococcus oeni ATCC-BAA1163 et Lactococcus lactis MG1363." Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00605353.

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Les résultats obtenus dans ce travail ont permis de démontrer que chez les deux bactéries lactiques modèles, L. lactis subsp. cremoris et O. oeni, la transcription du gène cfa, codant pour la Cfa synthase, est stimulée lorsque les cellules entrent en phase stationnaire de croissance ou lorque que les cellules sont cultivées en conditions de stress (milieu acide ou présence d'éthanol dans le milieu). Le rôle des CFA a pû être appréhendé par l'analyse physiologique comparative de la souche parentale L. lactis subsp. cremoris et du mutant Δcfa généré chez cette souche. Les forts pourcentages de survie obtenus chez les souches cultivées à pH 5,0, puis subissant un stress acide (pH 3,0), prouvent que la cyclopropanation des acides gras insaturés n'est pas indispensable à la survie de L. lactis subsp. cremoris en conditions de stress acide. En outre, les données d'anisotropie de fluorescence démontrent que la présence de CFAs membranaires ne permet pas de réguler le niveau de fluidité membranaire, en particulier avec les souches cultivées en présence d'éthanol, où une fluidification membranaire est observée dans tous les cas. L'hypothèse d'un équilibre entre les acides palmitoléique / cis-vaccénique / lactobacillique pour réguler la fluidité membranaire chez L. lactis subsp. cremoris est avancée. L'étude du rôle physiologique des CFA chez O. oeni nécessite l'expression du gène cfa de la bactérie en système hétérologue. Les résultats obtenus confirment la fonctionnalité du gène chez la bactérie hôte L. lactis subsp. cremoris, cependant la cyclisation du précurseur acide cis-vaccénique, reste partielle chez la souche mutante complémentée. Un travail de caractérisation biochimique in vitro de l'enzyme Cfa synthase de O. oeni a donc été entrepris afin d'expliquer la faible efficacité de l'enzyme de O. oeni chez la bactérie hôte. Les travaux réalisés ont permis la surproduction et la purification de l'enzyme. Une technique de mesure d'activité in vitro a été également développée. Une stratégie d'expression du gène cfa de O. oeni en système hétérologue dans la bactérie hôte E. coli BL21 Star a permis la surpoduction d'une protéine d'environ 45 kDa, en accord avec la masse moléculaire théorique de la Cfa synthase de O. oeni. A partir de l'extrait protéique, une purification a été réalisée par chromatographie d'affinité sur colonne d'agarose nickel. Les tests d'activité enzymatique in vitro ont pu été réalisés. La température optimale de l'enzyme est de 35,8°C. Son pH optimal est de 5,6. Même en se plaçant dans les conditions physico-chimiques optimales de l'enzyme, nous constatons que la cyclisation in vitro de l'acide cis-vaccénique issu des phospholipides membranaires du mutant L. lactis subsp. cremoris Δcfa reste partielle. Ceci induit une détermination expérimentale de valeurs de KM et Vmax largement supérieures aux données citées dans la littérature. La différence, entre les deux bactéries modèles, de nature et de répartition des phospholipides membranaires pourrait expliquer l'action partielle de la Cfa synthase de O. oeni.
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Creuly, Catherine. "Selection d'une collection industrielle de streptocoques mesophiles et thermophiles en vue de leurs utilisations en rotation dans les ferments lactiques." Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF2D206.

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Cette etude a contribue a creer une collection de streptocoques lactiques: st. Lactis subsp. Cremoris, st. Lactis subsp. Lactis, st. Lactis subsp. Diacetylactis (bacteries mesophiles) et st. Thermophilus. Onze souches de st. Cremoris appartenant a la collection existante ont ete selectionnees parmi 67 bacteries mesophiles apres des tests de lysotypie (sur 59 phages) et de lysogenie (par action de la mitomycine). Les memes tests ont ete realises sur 30 st. Thermophilus et 19 serums phagiques. Mais ces souches semblent posseder des systemes de restriction-modification puissants et sont donc moins sensibles aux phages. Le peu de phages recoltes n'ont pas permis d'etablir des groupes de lysotypie significatifs et les souches testees ne sont pas lysogenes. Afin d'ameliorer la collection, 554 bacteries mesophiles ont ete isolees; identifiees et leur pouvoir acidifiant determine
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Bibal, Bernard. "Dynamique de croissance de Streptococcus cremoris et comportement en réacteur à haute densité cellulaire." Toulouse, INSA, 1989. http://www.theses.fr/1989ISAT0034.

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Dans le cadre de la production de levains lactiques concentres, l'augmentation des productivites peut etre realisee par l'utilisation d'un reacteur couple a un etage de filtration par procede membranaire. L'etude prealable du comportement cinetique de cultures de streptococcus cremoris en culture discontinue fait apparaitre l'importance de l'inhibition par l'acide lactique, produit majoritaire de la fermentation. Toutefois, l'effet du produit ne suffit pas a expliquer le deroulement cinetique de la croissance, mettant en evidence l'existence de limitations nutritionnelles. Les cinetiques d'epuisement du milieu ont ete etudiees et l'influence relative des phenomenes d'inhibition et de limitation a ete quantifiee aussi bien en cultures discontinues qu'en chemostat. Lors de cultures a recyclage de biomasse, la comparaison de la dynamique de croissance et de production d'acide lactique a celle qui caracterise les potentialites de la souche, a permis de mettre en evidence l'effet des variables operatoires specifiques du bioreacteur a membrane sur les cinetiques biologiques. Ainsi, l'influence des conditions de recirculation du milieu de culture est aborde sous l'angle des vitesses de reaction et de l'activite cellulaire. Le role du taux de dilution est precise par rapport aux mecanismes d'inhibition/limitation de la croissance et l'interet de la mise en uvre d'une purge de biomasse est discute sous l'angle des rendements de culture. Un modele de connaissance, decrivant la croissance de streptococcus cremoris et la production d'acide lactique est propose pour globaliser les effets de ces differentes variables
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Books on the topic "Lactococcus lactis subsp. cremoris"

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Salama, Maysoon. The isolation of Lactococcus lactis subsp. cremoris from nature with probes for 16S ribosomal RNAs. 1993.

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Book chapters on the topic "Lactococcus lactis subsp. cremoris"

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Le Bourgeois, P., M. L. Mingot-Daveran, and Paul Ritzenthaler. "Lactococcus lactis subsp. lactis ILI403 and Lactococcus lactis subsp. cremoris MG1363." In Bacterial Genomes. Springer US, 1998. http://dx.doi.org/10.1007/978-1-4615-6369-3_64.

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Davey, Graham P. "Diplococcin Produced by Lactococcus Lactis Subsp. Cremoris." In Bacteriocins of Lactic Acid Bacteria. Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-2668-1_8.

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Piard, Jean-Christophe. "Lacticin 481, A Lantibiotic Produced by Lactococcus Lactis Subsp. Lactis CNRZ 481." In Bacteriocins of Lactic Acid Bacteria. Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-2668-1_7.

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De Vuyst, Luc, and Erick J. Vandamme. "Nisin, A Lantibiotic Produced by Lactococcus Lactis Subsp. Lactis: Properties, Biosynthesis, Fermentation and Applications." In Bacteriocins of Lactic Acid Bacteria. Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-2668-1_5.

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Wang, Shichao, Shuxin Zhao, Hongxia Mu, Fengyun Sun, and Peng Chen. "Effect of Lactococcus lactis subsp. on Production of Pigment and Citrinin by Monascus." In Proceedings of the 2012 International Conference on Applied Biotechnology (ICAB 2012). Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-37925-3_170.

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De Vuyst, Luc, and Erick J. Vandamme. "Localization and Phenotypic Expression of Genes Involved in the Biosynthesis of the Lactococcus Lactis subsp. Lactis Lantibiotic Nisin." In Bacteriocins, Microcins and Lantibiotics. Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-76974-0_40.

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Demarigny, Y. "LACTOCOCCUS | Lactococcus lactis Subspecies lactis and cremoris." In Encyclopedia of Food Microbiology. Elsevier, 2014. http://dx.doi.org/10.1016/b978-0-12-384730-0.00182-8.

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Courtney, Polly D. "LACTOCOCCUS | Lactococcus Lactis Subspecies Lactis and Cremoris." In Encyclopedia of Food Microbiology. Elsevier, 1999. http://dx.doi.org/10.1006/rwfm.1999.0920.

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Mercade, M., M. Cocaign-bousquet, N. D. Lindley, and P. Loubière. "Regulation of glycolysis of Lactococcus lactis ssp. cremoris MG 1363 at acidic culture conditions." In Progress in Biotechnology. Elsevier, 2000. http://dx.doi.org/10.1016/s0921-0423(00)80079-9.

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Conference papers on the topic "Lactococcus lactis subsp. cremoris"

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Guo, Wei-liang, Shuang Yang, Xue Li, Guo-dong Yan, Jia-hui Lu, and Chang-ji Yuan. "Two Modeling Methods for Optimization of the Culture Conditions for Nisin Production by Lactococcus Lactis Subsp. Lactis." In 2010 International Conference on Artificial Intelligence and Computational Intelligence (AICI). IEEE, 2010. http://dx.doi.org/10.1109/aici.2010.69.

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