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Tournier L, Rivet G, Brenans AC, Bosserdet L, Petrucci N, Monnet C. [Evaluation of domestic violence situations by the Crip]. Soins Pediatr Pueric 2023; 44:10-16. [PMID: 37024176 DOI: 10.1016/j.spp.2023.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Thanks to the progress of scientific research, children who witness domestic violence are now recognized as direct victims. The cells for the collection of information of concern (Crip) carry out a pre-assessment of situations where the child is in danger or at risk of danger, including those of domestic violence. Not all Crips are organized in the same way in the country, although their missions are identical.
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Affiliation(s)
- Lila Tournier
- Cellule de recueil des informations préoccupantes du Doubs, 28 rue Mégevand, 25000 Besançon, France.
| | - Gérard Rivet
- Cellule de recueil des informations préoccupantes du Doubs, 28 rue Mégevand, 25000 Besançon, France
| | - Anne-Claire Brenans
- Cellule de recueil des informations préoccupantes du Doubs, 28 rue Mégevand, 25000 Besançon, France
| | - Lucile Bosserdet
- Cellule de recueil des informations préoccupantes du Doubs, 28 rue Mégevand, 25000 Besançon, France
| | - Nathalie Petrucci
- Cellule de recueil des informations préoccupantes du Doubs, 28 rue Mégevand, 25000 Besançon, France
| | - Catherine Monnet
- Cellule de recueil des informations préoccupantes du Doubs, 28 rue Mégevand, 25000 Besançon, France
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Irlinger F, Monnet C. Temporal differences in microbial composition of Époisses cheese rinds during ripening and storage. J Dairy Sci 2021; 104:7500-7508. [PMID: 33838885 DOI: 10.3168/jds.2021-20123] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 02/24/2021] [Indexed: 12/30/2022]
Abstract
Époisses is a protected designation of origin smear-ripened cheese from the Burgundy region in France. It has an orange color and a strong flavor, both of which are generated by surface microorganisms. The objective of the present study was to investigate the microbial dynamics at the surface of Époisses cheese during ripening and postmanufacturing storage at low temperatures. Rind samples were analyzed by enumeration on agar plates and by 16S rRNA gene and internal transcribed spacer amplicon sequencing. During most of the ripening process, the counts of yeasts, which corresponded to the species Debaryomyces hansenii and Geotrichum candidum, were higher than those of the aerobic acid-sensitive bacteria. Debaryomyces hansenii reached a level of about 3 × 108 cfu/cm2, and its viability strongly decreased in the late stage of ripening and during storage at 4°C. Two of the inoculated bacterial species, Brevibacterium aurantiacum and Staphylococcus xylosus, did not establish themselves at the cheese surface. At the end of ripening, among the 18 most abundant bacterial species detected by amplicon sequencing, 14 were gram-negative, mainly from genera Psychrobacter, Vibrio, Halomonas, and Mesonia. It was hypothesized that the high moisture level of the Époisses rinds, due the humid atmosphere of the ripening rooms and to the frequent washings of the curds, favored growth of these gram-negative species. These species may be of interest for the development of efficient ripening cultures. In addition, because the orange color of Époisses cheeses could not be attributed to the growth of Brevibacterium, it would be interesting to investigate the type and origin of the pigments that confer color to this cheese.
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Affiliation(s)
- F Irlinger
- Université Paris-Saclay, INRAE, AgroParisTech, UMR SayFood, 78850 Thiverval-Grignon, France
| | - C Monnet
- Université Paris-Saclay, INRAE, AgroParisTech, UMR SayFood, 78850 Thiverval-Grignon, France.
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Zahra N, Monnet C, Bartha E, Bouilhol G, Boydev C, Courbis M, Le Grévellec M, Bosset M, Zouai M, Fleury B, Clippe S. [Interobserver variability study for daily cone beam computed tomography registration of prostate volumetric modulated arc therapy]. Cancer Radiother 2015. [PMID: 26206733 DOI: 10.1016/j.canrad.2015.04.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE This work evaluated the interobserver variability in cone beam computed tomography (CBCT) registration for prostate cancers treated with intensity-modulated radiotherapy. MATERIAL AND METHODS Twelve technologists realized 286 CBCT/CT registrations (bone registration followed by prostate to prostate registration). The registration results were compared to those obtained by two radiation oncologists (reference). Each technologist reported the shifts calculated by the software in all three axes. A statistical analysis allowed us to calculate the minimum threshold under which 95% of the observers found similar values. A variance analysis followed by the post hoc test were used to find differences in interobserver registration variability and determine whether any individual users performed registrations which differed significantly from those of the other users. RESULTS The registration differences compared to the reference in the three directions in terms of 95th percentile are: 2.1mm left-right, 3.5mm target-gun, 7.3mm anterior-posterior. In the posterior direction, 4% of the observers have found differences superior to 8mm, margin used in routine without the use of a daily CBCT. The variance test revealed a P-value <0.05 only for target-gun and for all observers there was no significant difference compared to the reference. CONCLUSION This study confirmed the interest of a 3D tissue registration for prostate treatments. The registration study showed a good interobserver reproducibility. This showed the importance of a daily CBCT/CT registration in prostate treatment with the possibility of a planning target volume margin reduction in the three directions. An evaluation of a partial delegation of registration to technologists should be done by the radiation oncologists.
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Affiliation(s)
- N Zahra
- Centre de radiothérapie Marie-Curie, 159, boulevard Maréchal-Juin, 26000 Valence, France.
| | - C Monnet
- Centre de radiothérapie Marie-Curie, 159, boulevard Maréchal-Juin, 26000 Valence, France
| | - E Bartha
- Centre de radiothérapie Marie-Curie, 159, boulevard Maréchal-Juin, 26000 Valence, France
| | - G Bouilhol
- Institut Curie, hôpital René-Huguenin, 35, rue Dailly, 92210 Saint-Cloud, France
| | - C Boydev
- Laboratoire de traitement des signaux 5 (LTS5), école polytechnique fédérale de Lausanne (EPFL), EPFL-STI-IEL-LTS5 Station 11, 1015 Lausanne, Suisse
| | - M Courbis
- Centre de radiothérapie Marie-Curie, 159, boulevard Maréchal-Juin, 26000 Valence, France
| | - M Le Grévellec
- Centre de radiothérapie Marie-Curie, 159, boulevard Maréchal-Juin, 26000 Valence, France
| | - M Bosset
- Centre de radiothérapie Marie-Curie, 159, boulevard Maréchal-Juin, 26000 Valence, France
| | - M Zouai
- Centre de radiothérapie Marie-Curie, 159, boulevard Maréchal-Juin, 26000 Valence, France
| | - B Fleury
- Centre de radiothérapie Marie-Curie, 159, boulevard Maréchal-Juin, 26000 Valence, France
| | - S Clippe
- Centre de radiothérapie Marie-Curie, 159, boulevard Maréchal-Juin, 26000 Valence, France
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Zahra N, Monnet C, Bartha E, Courbis M, Le Grévellec M, Bosset M, Zouai M, Fleury B. EP-1657: Inter-observer variability study for daily CBCT registration of VMAT prostate treatment. Radiother Oncol 2015. [DOI: 10.1016/s0167-8140(15)41649-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Trmčić A, Monnet C, Rogelj I, Bogovič Matijašić B. Expression of nisin genes in cheese—A quantitative real-time polymerase chain reaction approach. J Dairy Sci 2011; 94:77-85. [DOI: 10.3168/jds.2010-3677] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Accepted: 10/05/2010] [Indexed: 11/19/2022]
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Dubreuil D, Renaut L, Monnet C, Carles M, Souyris N, Zaki O, Lazrek Y, Crozet F, Bouayadi K, Kharrat H, Mondon P. R156: Sélection d’anticorps humains contre des cibles impliquées dans différents cancers. Bull Cancer 2010. [DOI: 10.1016/s0007-4551(15)31077-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Monnet C, Jorieux S, Souyris N, Zaki O, Morlec R, Crozet F, Fontayne A, De Romeuf C, Kharrat H, Urbain R, Bouayadi K, Behrens C, Mondon P. R108: Ingénierie génétique de la région Fc des anticorps humains en vue d’améliorer leur demi-vie plasmatique. Bull Cancer 2010. [DOI: 10.1016/s0007-4551(15)31027-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Mansour S, Bailly J, Landaud S, Monnet C, Sarthou AS, Cocaign-Bousquet M, Leroy S, Irlinger F, Bonnarme P. Investigation of associations of Yarrowia lipolytica, Staphylococcus xylosus, and Lactococcus lactis in culture as a first step in microbial interaction analysis. Appl Environ Microbiol 2009; 75:6422-30. [PMID: 19684166 PMCID: PMC2765154 DOI: 10.1128/aem.00228-09] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Accepted: 08/10/2009] [Indexed: 11/20/2022] Open
Abstract
The interactions that may occur between microorganisms in different ecosystems have not been adequately studied yet. We investigated yeast-bacterium interactions in a synthetic medium using different culture associations involving the yeast Yarrowia lipolytica 1E07 and two bacteria, Staphylococcus xylosus C2a and Lactococcus lactis LD61. The growth and biochemical characteristics of each microorganism in the different culture associations were studied. The expression of genes related to glucose, lactate, and amino acid catabolism was analyzed by reverse transcription followed by quantitative PCR. Our results show that the growth of Y. lipolytica 1E07 is dramatically reduced by the presence of S. xylosus C2a. As a result of a low amino acid concentration in the medium, the expression of Y. lipolytica genes involved in amino acid catabolism was downregulated in the presence of S. xylosus C2a, even when L. lactis was present in the culture. Furthermore, the production of lactate by both bacteria had an impact on the lactate dehydrogenase gene expression of the yeast, which increased up to 30-fold in the three-species culture compared to the Y. lipolytica 1E07 pure culture. S. xylosus C2a growth dramatically decreased in the presence of Y. lipolytica 1E07. The growth of lactic acid bacteria was not affected by the presence of S. xylosus C2a or Y. lipolytica 1E07, although the study of gene expression showed significant variations.
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Affiliation(s)
- S Mansour
- Agro Paris Tech-INRA, UMR 782 Génie et Microbiologie des Procédés Alimentaires, 78850 Thiverval Grignon, France
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Mounier J, Monnet C, Jacques N, Antoinette A, Irlinger F. Assessment of the microbial diversity at the surface of Livarot cheese using culture-dependent and independent approaches. Int J Food Microbiol 2009; 133:31-7. [PMID: 19481828 DOI: 10.1016/j.ijfoodmicro.2009.04.020] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 02/09/2009] [Accepted: 04/14/2009] [Indexed: 10/20/2022]
Abstract
The microbial diversity of the surface of a commercial red-smear cheese, Livarot cheese, sold on the retail market was studied using culture-dependent and independent approaches. Forty yeasts and 40 bacteria from the cheese surface were collected, dereplicated using single-strand conformation polymorphism (SSCP) analysis and identified using rRNA gene sequencing for the culture-dependent approach. The culture-independent approach involved cloning and sequencing of the 16S rRNA gene and SSCP analysis from total DNA extracted from the cheese. The most dominant bacteria were Microbacterium gubbeenense, Leucobacter komagatae and Gram-negative bacteria from the Gamma-Proteobacteria class. Fluorescence in situ hybridization (FISH) analysis was also used to study the cheese microbial diversity with class-level and specific rRNA-targeted probes for bacteria and yeasts, respectively. FISH analysis confirmed that Gamma-Proteobacteria were important microorganisms in this cheese. Four specific FISH probes targeting the dominant yeasts present in the cheese, Candida catenulata, Candida intermedia, Geotrichum spp. and Yarrowia lipolytica, were also designed and evaluated. These probes allowed the detection of these yeasts directly in cheese. The use of the rRNA gene-based approach combined with FISH analysis was useful to investigate the diversity of a surface microbial consortium from cheese.
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Affiliation(s)
- J Mounier
- UMR Génie et Microbiologie des Procédés Alimentaires, INRA, AgroParisTech, Thiverval Grignon, France
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Abstract
AIMS Some fungi present on the surface of grapes may have a negative effect on the quality of wine. The aim of this study was to evaluate PCR-denaturing gradient gel electrophoresis (PCR-DGGE), for the establishment of fungal community profiles from grapes, in order to monitor fungi potentially involved in wine defects. METHODS AND RESULTS A fragment of the beta-tubulin gene was amplified from filamentous fungi and yeasts described from grapes and analysed using two different denaturing gradient gels to constitute a reference database. The use of beta-tubulin sequences instead of ITS rDNA in PCR-DGGE showed a progress in the discrimination of these fungal species but comigration problems were still observed. The technique was then applied on grape samples. The profiles counted up to 10 bands of which half corresponded to species which were not recorded in the reference database. CONCLUSION PCR-DGGE represents a useful tool to compare environmental samples for the study of the dynamics of fungal communities, but comigrations represent a limit in its use to describe the species present. SIGNIFICANCE AND IMPACT OF THE STUDY A better knowledge of the fungal diversity on grapes, particularly species responsible for wine defect, is necessary to develop accurate molecular detection tools.
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Affiliation(s)
- R Laforgue
- IFV - Institut Français de la Vigne et du Vin, Tours Cedex, France.
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Arioli S, Monnet C, Guglielmetti S, Mora D. Carbamoylphosphate synthetase activity is essential for the optimal growth of Streptococcus thermophilus in milk. J Appl Microbiol 2009; 107:348-54. [PMID: 19302299 DOI: 10.1111/j.1365-2672.2009.04213.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM The aim of the study was to study the role of carbon dioxide metabolism in Streptococcus thermophilus through investigation of the phenotype of a carbamoylphosphate synthetase-negative mutant. METHODS AND RESULTS The effect of carbon dioxide on the nutritional requirements of Strep. thermophilus DSM20617(T) and its derivative, carbamoylphosphate synthetase-negative mutant A17(DeltacarB), was investigated by cultivating the strain in a chemically defined medium under diverse gas compositions and in milk. The results obtained revealed that CO(2) depletion or carB gene inactivation determined the auxotrophy of Strep. thermophilus for l-arginine and uracil. In addition, the parent strain grew faster than the mutant, even when milk was supplemented with uracil or arginine. CONCLUSIONS Milk growth experiments underlined that carbamoylphosphate synthetase activity was essential for the optimal growth of Strep. thermophilus in milk. SIGNIFICANCE AND IMPACT OF THE STUDY The study of the carbon dioxide metabolism in Strep. thermophilus revealed new insights with regard to the metabolism of this species, which could be useful for the optimization of dairy fermentation processes.
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Affiliation(s)
- S Arioli
- Department of Food Science and Microbiology, University of Milan, Milan, Italy.
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Ulve VM, Monnet C, Valence F, Fauquant J, Falentin H, Lortal S. RNA extraction from cheese for analysis of in situ gene expression of Lactococcus lactis. J Appl Microbiol 2008; 105:1327-33. [PMID: 18795980 DOI: 10.1111/j.1365-2672.2008.03869.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS The isolation of high-quality RNA from cheese is a prerequisite for analysis of in situ gene expression of dairy micro-organisms. METHODS AND RESULTS A method for rapid isolation of bacterial cells from cheese using cold citrate buffer followed by mechanical cell disruption was developed. RNA was extracted from experimental ultrafiltration (UF) cheeses (at 2, 8, 24 h, 7 and 14 days) and from Cheddar cheese (from 1 day to 1 year). The quantity and quality of the extracted RNA was assessed. The transcript abundance of seven genes (tuf, gapB, purM, cysK, ldh, cit and gyrA) was estimated by reverse transcription real-time PCR. In UF cheeses, the quantity of RNA extracted increased from 0.2 to 24 microg g(-1), with an RNA Integrity Number (RIN) above 9. In the experimental Cheddar cheeses, the RNA extraction yield decreased from 67.7 microg g(-1) after 1 day to 23.7 microg g(-1) after 6 months, with RIN value above 9 during the first month. The transcript abundance of the seven genes demonstrated metabolic activity of lactococci after several weeks of ripening in both cheeses. SIGNIFICANCE AND IMPACT OF THE STUDY The method described produced large quantities of high-quality RNA for future whole genome expression studies in cheese.
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Affiliation(s)
- V M Ulve
- UMR1253, Science et Technologie du Lait et de l'OEuf, INRA, Rennes, France
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Lacoste JF, Bounor-Legaré V, Joubert C, Llauro MF, Monnet C, Cassagnau P, Michel A. Crosslinking of PET through solid state functionalization with alkoxysilane derivatives. POLYMER 2007. [DOI: 10.1016/j.polymer.2007.06.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Mora D, Monnet C, Daffonchio D. Balancing the loss and acquisition of pathogenic traits in food-associated bacteria. Microbiology (Reading) 2006; 151:3814-3816. [PMID: 16339928 DOI: 10.1099/mic.0.28513-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- D Mora
- Department of Food Science and Microbiology, University of Milan, via Celoria 2, 20133 Milan, Italy
| | - C Monnet
- Unité Mixte de Recherche Génie et Microbiologie des Procédés Alimentaires, Institut National de la Recherche Agronomique, 78850 Thiverval-Grignon, France
| | - D Daffonchio
- Department of Food Science and Microbiology, University of Milan, via Celoria 2, 20133 Milan, Italy
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Aymes F, Monnet C, Corrieu G. Effect of alpha-acetolactate decarboxylase inactivation on alpha-acetolactate and diacetyl production by Lactococcus lactis subsp. lactis biovar diacetylactis. J Biosci Bioeng 2005; 87:87-92. [PMID: 16232430 DOI: 10.1016/s1389-1723(99)80013-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/1998] [Accepted: 11/15/1998] [Indexed: 10/18/2022]
Abstract
Strains of Lactococcus lactis subsp. lactis biovar diacetylactis deficient in alpha-acetolactate decarboxylase produce alpha-acetolactate. This unstable compound is a precursor of acetoin and an aromatic compound, diacetyl. Following random mutagenesis of strain CNRZ 483, alpha-acetolactate decarboxylase-negative mutant 483 M1 was selected. When grown in milk, its growth and acidification characteristics were similar to those of the parental strain. In anaerobic conditions, the parental strain produced 2.10 mM acetoin and less than 0.05 mM diacetyl. The mutant accumulated up to 2.11 mM alpha-acetolactate, which spontaneously degraded to acetoin and diacetyl. After 24 h of culture, the alpha-acetolactate concentration was only 0.49 mM and the acetoin and diacetyl concentrations reached 1.50 mM and 0.26 mM, respectively. Diacetyl production by both strains increased in aerobic conditions, as well as when citrate was added. In contrast to cultures of the parental strain, however, diacetyl and acetoin concentrations in mutant cultures continued to increase without reaching a plateau. The results also showed that diacetyl production by wild type L. lactis subsp. lactis biovar diacetylactis strains cannot be explained uniquely by the spontaneous decarboxylation of the alpha-acetolactate produced in the culture medium.
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Affiliation(s)
- F Aymes
- Laboratoire de Génie et Microbiologie des Procédés Alimentaires, Institut National de la Recherche Agronomique, 78850 Thiverval-Grignon, France
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Lacoste JF, Bounor-Legaré V, Llauro MF, Monnet C, Cassagnau P, Michel A. Functionalization of poly(ethylene terephthalate) in the melt state: Chemical and rheological aspects. ACTA ACUST UNITED AC 2005. [DOI: 10.1002/pola.20696] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Natural variations of the urea content of milk have a detrimental effect on the regularity of acidification by Streptococcus thermophilus strains used in dairy processes. The aim of the present study was to select urease-deficient mutants of S. thermophilus and to investigate their properties. Using an improved screening medium on agar plates, mutants were selected from 4 different parent strains after mutagen treatment and by spontaneous mutation. Most mutants were stable and had a phage sensitivity profile similar to that of their parent strain. Some of them contained detrimental secondary mutations, as their acidifying activity was lower than that of the parent strain cultivated in the presence of the urease inhibitor flurofamide. The proportion of this type of mutant was much lower among spontaneous mutants than among mutants selected after mutagen treatment. Utilization of urease-deficient mutants in dairy processes may have several advantages, such as an increase in acidification, an improved regularity of acidification, and a lower production of ammonia in whey.
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Affiliation(s)
- C Monnet
- Unité Mixte de Recherche Génie et Microbiologie des Procédés Alimentaires, Institut National de la Recherche Agronomique, 78850 Thiverval-Grignon, France.
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Abstract
One of the main functions of Streptococcus thermophilus strains used in the dairy industry is the production of lactic acid. In cheese and fermented milk manufacturing processes, the pH evolution kinetics must be reproducible in order to ensure the good quality of the final products. The objective of the present study was to investigate the effect of the metabolism of urea on the acidifying activity of fast- and slow-acidifying strains of S. thermophilus. Milk treatment with a purified urease and utilization of the urease inhibitor flurofamide revealed that urea metabolism by S. thermophilus influences the pH evolution kinetics through 2 distinct means. First, ammonia production from urea tends to increase the pH. This effect is greater when lactic acid concentration is low due to a lower buffering capacity of milk. Second, urea metabolism also modifies growth and lactic acid production by S. thermophilus. Depending on the strains and the growth stage of the cultures, consumption of urea induces either a faster or a slower pH decrease. For the slow-acidifying strain RD678, suppression of urea metabolism by adding flurofamide decreased the time necessary to reach pH 6 by 195 min. This effect was less pronounced for the 2 fast-acidifying strains RD674 and RD677. These results show that urea metabolism may have a considerable influence on the acidifying properties of S. thermophilus strains.
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Affiliation(s)
- S Pernoud
- Unité Mixte de Recherche Génie et Microbiologie des Procédés Alimentaires, Institut National de la Recherche Agronomique, 78850 Thiverval-Grignon, France
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Lucas A, Sodini I, Monnet C, Jolivet P, Corrieu G. Probiotic cell counts and acidification in fermented milks supplemented with milk protein hydrolysates. Int Dairy J 2004. [DOI: 10.1016/s0958-6946(03)00147-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
Lactic acid bacteria are often produced as frozen or freeze-dried cultures that can be used for the direct inoculation of milk in cheese and fermented milk production processes. The objective of this study was to investigate whether the resistance of Lactobacillus delbrueckii ssp. bulgaricus to freezing could be improved by natural selection. Three parallel cultures of strain CFL1 were propagated for 30 cycles in which each cycle involved three serial transfers through milk, one freezing step, and one thawing step. The concentration in viable cells after thawing as well as the acidifying activity of the thawed cultures increased dramatically throughout the experiment. This may be explained by the random appearance of better-adapted mutants that can outcompete the other genotypes. However, after 30 cycles of subcultivation, freezing, and thawing, all the cultures contained subpopulations having different survival rates to freezing. Our results show that serial transfer culture experiments may be used to improve technological properties of lactic acid bacteria. Furthermore, investigation of the mutations that are responsible for an increased cryotolerance may help to define new targets for improving the resistance of lactic acid bacteria to several stresses.
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Affiliation(s)
- C Monnet
- Unité Mixte de Recherche Génie et Microbiologie des Procédés Alimentaires, Institut National de la Recherche Agronomique, 78850 Thiverval-Grignon, France.
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Monnet C, Nardi M, Hols P, Gulea M, Corrieu G, Monnet V. Regulation of branched-chain amino acid biosynthesis by alpha-acetolactate decarboxylase in Streptococcus thermophilus. Lett Appl Microbiol 2003; 36:399-405. [PMID: 12753249 DOI: 10.1046/j.1472-765x.2003.01326.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS To demonstrate the presence of an active alpha-acetolactate decarboxylase in Streptococcus thermophilus and to investigate its physiological function. METHODS AND RESULTS Streptococcus thermophilus CNRZ385 contains a gene encoding an alpha-acetolactate decarboxylase. Comparison of the production of alpha-acetolactate and its decarboxylation products, by the parent strain and an alpha-acetolactate decarboxylase-deficient mutant, demonstrated the presence of a control of the pool of alpha-acetolactate by valine, leucine and isoleucine. This control occurs via an allosteric activation of the alpha-acetolactate decarboxylase. Cell-free extracts of S. thermophilus were not able to decarboxylate the isoleucine precursor alpha-acetohydroxybutyrate. CONCLUSIONS These results strongly suggest that one of the physiological functions of the alpha-acetolactate decarboxylase in S. thermophilus is to regulate leucine and valine biosynthesis by diverting the flux of alpha-acetolactate towards acetoin when the branched-chain amino acids are present at a high concentration. SIGNIFICANCE AND IMPACT OF THE STUDY Regulation of branched-chain amino acid biosynthesis by alpha-acetolactate decarboxylase may occur in several other micro-organisms and explain some of their growth properties.
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Affiliation(s)
- C Monnet
- Unité Mixte de Recherche Génie et Microbiologie des Procés Alimentaires, Institut National de la Recherche Agronomique, Thiverval-Grignon, France.
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Soula R, Saillard B, Spitz R, Claverie J, Llaurro MF, Monnet C. Catalytic Copolymerization of Ethylene and Polar and Nonpolar α-Olefins in Emulsion. Macromolecules 2002. [DOI: 10.1021/ma011366e] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Monnet C, Bettsworth F, Stura EA, Le Du MH, Ménez R, Derrien L, Zinn-Justin S, Gilquin B, Sibaï G, Battail-Poirot N, Jolivet M, Ménez A, Arnaud M, Ducancel F, Charbonnier JB. Highly specific anti-estradiol antibodies: structural characterisation and binding diversity. J Mol Biol 2002; 315:699-712. [PMID: 11812141 DOI: 10.1006/jmbi.2001.5284] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Subtle modulation of antibody-binding properties by protein engineering often lies with an accurate structural and energetic description of how an antigen is recognised. Thus, with the intent to increase the affinity and add a bias in favour of natural estradiol compared with its chemically modified immunogen, we have determined the crystal structure of two anti-estradiol monoclonal antibodies, 10G6D6 and 17E12E5. Although generated against the same estradiol derivative, these antibodies share little sequence identity, which is reflected in dissimilar binding pockets and in different positioning of the steroid. In both antibodies the characteristic 17-hydroxyl group is buried deeply at the bottom of hydrophobic pockets and stabilised by hydrogen bonds. Apart from this similarity, the steroid is oriented differently in the respective binding pockets. The high specificity of both antibodies has been mapped out, and even closely related steroids show low cross-reactivity. The structural studies of the complex formed between 10G6D6 and 6-CMO-estradiol have identified contacts between the 6-CMO coupling linker and an arginine residue from the heavy chain CDR2 segment. This segment is now being targeted by random mutagenesis to select mutants with a preference for natural estradiol compared to the branched hapten.
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Affiliation(s)
- C Monnet
- Département d'Ingénierie et d'Etude des Protéines, CEA, CE Saclay, Gif-sur-Yvette Cedex, 91191, France
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Bettsworth F, Monnet C, Watelet B, Battail-Poirot N, Gilquin B, Jolivet M, Menez A, Arnaud M, Ducancel F. Functional characterization of two anti-estradiol antibodies as deduced from modelling and site-directed mutagenesis experiments. J Mol Recognit 2001; 14:99-109. [PMID: 11301480 DOI: 10.1002/jmr.525] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Monoclonal antibodies are now widely used to measure the concentration of steroid hormones in human serum samples. The great development of molecular engineering techniques over the past 10 years has made possible the improvement of specificity and/or sensitivity of selected antibodies. We have obtained two monoclonal antibodies, 17E12E5 and 10G6D6, using estradiol-6-ethyl methoxy carbonyl (EMC)-bovine serum albumin (BSA) as immunogen. To tentatively improve their affinities for natural estradiol, we have initiated their structural and functional studies. For this purpose, we have cloned and sequenced the genes encoding the variable fragments of each antibody. Single chain variable fragments (scFv) were produced into the periplasmic space of E. coli using the pLIP6 expression vector. Mapping of the functional structures of both antibodies was obtained by combination of modelling and mutational analyses together with cross-reaction studies. The two binding pockets are described and models of estradiol complexed to 17E12E5 and 10G6D6 are proposed.
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Affiliation(s)
- F Bettsworth
- Département R&D immunoessais, bioMérieux, Chemin de l'Orme, 69280 Marcy l'Etoile, France
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Monnet C, Aymes F, Corrieu G. Diacetyl and alpha-acetolactate overproduction by Lactococcus lactis subsp. lactis biovar diacetylactis mutants that are deficient in alpha-acetolactate decarboxylase and have a low lactate dehydrogenase activity. Appl Environ Microbiol 2000; 66:5518-20. [PMID: 11097941 PMCID: PMC92495 DOI: 10.1128/aem.66.12.5518-5520.2000] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lactococcus lactis subsp. lactis biovar diacetylactis strains are utilized in several industrial processes for producing the flavoring compound diacetyl or its precursor alpha-acetolactate. Using random mutagenesis with nitrosoguanidine, we selected mutants that were deficient in alpha-acetolactate decarboxylase and had low lactate dehydrogenase activity. The mutants produced large amounts of alpha-acetolactate in anaerobic milk cultures but not in aerobic cultures, except when the medium was supplemented with catalase, yeast extract, or hemoglobin.
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Affiliation(s)
- C Monnet
- Laboratoire de Génie et Microbiologie des Procédés Alimentaires, Institut National de la Recherche Agronomique, 78850 Thiverval-Grignon, France.
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Abstract
Mutants of Lactococcus lactis producing excess carbon dioxide could be isolated on LDHA-20 agar (described by El Attar et al. Journal of Dairy Research 67 641-646 2000). The use of these mutants in the manufacture of Roquefort cheese has the potential to improve the formation of openings in this cheese. The aim of this work was to examine the stability of these mutants, their enzymic activities and their metabolism of lactose and citrate during growth in milk. They produced less L-lactate than the parent strain and their lactate dehydrogenase activity was lower. Nevertheless none of the mutants produced no L-lactate at all and the most active gas generators among them generally produced 30-50 mM-L-lactate. Unexpectedly, all the strains produced some D-lactate, some > 10 mM. We found that carbon dioxide production by the mutants could be determined indirectly by assaying acetoin, citrate and 2,3-butanediol by high-performance liquid chromatography. Generally, spontaneous mutants were more stable than those obtained after treating with nitrosoguanidine or u.v. irradiation.
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Affiliation(s)
- A El Attar
- Laboratoire de Génie et Microbiologie des Procédés Alimentaires, Institut National de la Recherche Agronomique, Thiverval-Grignon, France
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Abstract
One of the characteristics of Roquefort cheese is the presence of irregularly
shaped openings. Although many factors affect the development of opening in blue-veined
cheeses (Martley & Crow, 1996), the limiting step in the case of Roquefort
cheese is the production of CO2 by lactic acid bacteria (J.-P. Reverbel, pers. comm.).
Most of the opening occurs after moulding; the process is difficult to control and
many manufacturing runs result in cheeses with an insufficient opening. Concentrated
suspensions of Leuconostoc strains are used to increase the production of CO2
(Devoyod & Muller, 1969), but it would clearly be useful to have microorganisms that
produce larger quantities of the gas. McKay & Baldwin (1974) isolated a spontaneous
mutant of Lactococcus lactis that produced more acetoin and CO2 than the parent
strain. This mutant was lactate dehydrogenase (LDH)-deficient, which favoured the
conversion of pyruvate into end products other than lactate. Following nitrosoguanidine
mutagenesis, we isolated three Lc. lactis mutants whose LDH activities
were reduced to varying extents and which produced varying amounts of CO2
(Boumerdassi et al. 1997). Subsequent work showed that these mutants were
unstable on successive subculture in milk or synthetic broth (El Attar et al. 2000).The aim of our current work was to select a large number of Lc. lactis mutants
producing excess CO2. This would increase the probability of selecting stable
mutants and also provide a collection of strains with differing gas production
activities. Currently available screening methods are, however, unsuitable for
processing large numbers of mutants, which is why we have developed an improved
screening method.
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Affiliation(s)
- A El Attar
- Laboratoire de Génie et Microbiologie des Procédés Alimentaires, Institut National de la Recherche Agronomique, Thiverval-Grignon, France
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Abstract
Alpha-Acetolactate-deficient Lactococcus lactis ssp. lactis biovar. diacelylactis are utilised in several industrial processes for producing diacetyl and alpha-acetolactate. They can be selected by screening after random mutagenesis. We improved a previously described screening method [Monnet, C., Schmitt, P., Diviès, C., 1997. Appl. Environ. Microbiol. 63, 793-795], which makes it possible to screen up to 1000 colonies per agar plate, whereas the previous method allowed to screen only 60 colonies per agar plate. The new screening method facilitates selection of alpha-acetolactate-deficient mutants.
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Affiliation(s)
- C Monnet
- Laboratoire de Génie et Microbiologie des Procédés Alimentaires, Institut National de la Recherche Agronomique, Thiverval-Grignon, France.
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Monnet C, Laune D, Laroche-Traineau J, Biard-Piechaczyk M, Briant L, Bès C, Pugnière M, Mani JC, Pau B, Cerutti M, Devauchelle G, Devaux C, Granier C, Chardès T. Synthetic peptides derived from the variable regions of an anti-CD4 monoclonal antibody bind to CD4 and inhibit HIV-1 promoter activation in virus-infected cells. J Biol Chem 1999; 274:3789-96. [PMID: 9920932 DOI: 10.1074/jbc.274.6.3789] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The monoclonal antibody (mAb) ST40, specific for the immunoglobulin complementarity-determining region (CDR) 3-like loop in domain 1 of the CD4 molecule, inhibits human immunodeficiency virus type 1 (HIV-1) promoter activity and viral transcription in HIV-infected cells. To design synthetic peptides from the ST40 paratope that could mimic these biological properties, a set of 220 overlapping 12-mer peptides frameshifted by one residue, corresponding to the deduced ST40 amino acid sequence, was synthesized by the Spot method and tested for binding to recombinant soluble CD4 antigen. Several peptides that included in their sequences amino acids from the CDRs of the antibody and framework residues flanking the CDRs were found to bind soluble CD4. Eleven paratope-derived peptides (termed CM1-CM11) were synthesized in a cyclic and soluble form. All the synthetic peptides showed CD4 binding capacity with affinities ranging from 1.6 to 86.4 nM. Moreover, peptides CM2, CM6, CM7, CM9, and CM11 were able to bind a cyclic peptide corresponding to the CDR3-like loop in domain 1 of CD4 (amino acids 81-92 of CD4). Peptide CM9 from the light chain variable region of mAb ST40 and, to a lesser extent, peptides CM2 and CM11 were able to inhibit HIV-1 promoter long terminal repeat-driven beta-galactosidase gene expression in the HeLa P4 HIV-1 long terminal repeat beta-galactosidase indicator cell line infected with HIV-1. The binding of mAb ST40 to CD4 was also efficiently displaced by peptides CM2, CM9, and CM11. Our results indicate that the information gained from a systematic exploration of the antigen binding capacity of synthetic peptides from immunoglobulin variable sequences can lead to the identification of bioactive paratope-derived peptides of potential pharmacological interest.
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Affiliation(s)
- C Monnet
- Faculté de Pharmacie, 15 Avenue Charles Flahault, 34060 Montpellier, France
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Abstract
The effect of citrate on the growth of Lactococcus lactis subsp. lactis var. diacetylactis in milk has been investigated. Five strains of Lactococcus lactis subsp. lactis var. diacetylactis were compared to their citrate-negative variants, which lack the plasmid coding for citrate permease. In most cases, acidification kinetics and the final bacterial concentration of pure cultures of parental and variant strains did not differ significantly. Co-cultures of parental and variant strains, however, systematically tended towards the predominance of parental strains. Citrate metabolism is responsible for this change, since the predominance of citrate-positive strains was not observed in the absence of citrate. Continuous culture in milk enabled the difference in growth rates between the parental strain Lactococcus lactis subsp. lactis var. diacetylactis CDI1 and its citrate-negative variant to be quantified by following changes in the populations of the two co-cultured strains. At 26 degrees C, the growth rate of the parental strain was 7% higher than that of its citrate-negative variant. These results show that citrate metabolism slightly stimulates the growth of lactococci in milk.
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Affiliation(s)
- S Haddad
- Laboratoire de Génie et Microbiologie des Procédés Alimentaires, Institut National de la Recherche Agronomique, Thiverval-Grignon, France
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Boumerdassi H, Monnet C, Desmazeaud M, Corrieu G. Isolation and properties of Lactococcus lactis subsp. lactis biovar diacetylactis CNRZ 483 mutants producing diacetyl and acetoin from glucose. Appl Environ Microbiol 1997; 63:2293-9. [PMID: 9172349 PMCID: PMC168522 DOI: 10.1128/aem.63.6.2293-2299.1997] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Following treatment with the mutagen N-methyl-N'-nitro-N-nitrosoguanidine, three mutants of Lactococcus lactis subsp. lactis biovar diacetylactis CNRZ 483 that produced diacetyl and acetoin from glucose were isolated. The lactate dehydrogenase activity of these mutants was strongly attenuated, and the mutants produced less lactate than the parental strain. The kinetic properties of lactate dehydrogenase of strain CNRZ 483 and the mutants revealed differences in the affinity of the enzyme for pyruvate, NADH, and fructose-1,6-diphosphate. When cultured aerobically, strain CNRZ 483 transformed 2.3% of glucose to acetoin and produced no diacetyl or 2,3-butanediol. Under the same conditions, mutants 483L1, 483L2, and 483L3 transformed 42.0, 78.9, and 75.8%, respectively, of glucose to C4 compounds (diacetyl, acetoin, and 2,3-butanediol). Anaerobically, strain CNRZ 483 produced no C4 compounds, while mutants 483L1, 483L2, and 483L3 transformed 2.0, 37.0, and 25.8% of glucose to acetoin and 2,3-butanediol. In contrast to the parental strain, the NADH balance showed that the mutants regenerated most of the NAD via NADH oxidase under aerobic conditions and by ethanol production under anaerobic conditions.
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Affiliation(s)
- H Boumerdassi
- Laboratoire de Génie et Microbiologie des Procédés Alimentaires, Institut National de la Recherche Agronomique, Thiverval Grignon, France
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Boumerdassi H, Monnet C, Desmazeaud M, Corrieu G. Effect of Citrate on Production of Diacetyl and Acetoin by Lactococcus lactis ssp. lactis CNRZ 483 Cultivated in the Presence of Oxygen. J Dairy Sci 1997. [DOI: 10.3168/jds.s0022-0302(97)75981-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Monnet C, Schmitt P, Divies C. Development and Use of a Screening Procedure for Production of (alpha)-Acetolactate by Lactococcus lactis subsp. lactis biovar diacetylactis Strains. Appl Environ Microbiol 1997; 63:793-5. [PMID: 16535527 PMCID: PMC1389533 DOI: 10.1128/aem.63.2.793-795.1997] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A method was developed to screen and isolate mutagenized Lactococcus lactis subsp. lactis biovar diacetylactis strains accumulating (alpha)-acetolactate. This compound is accumulated by (alpha)-acetolactate decarboxylase-deficient strains and undergoes spontaneous degradation into diacetyl on agar plates. The diacetyl produced is detected by a colorimetric reaction yielding a red halo around the colonies.
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Garmyn D, Monnet C, Martineau B, Guzzo J, Cavin JF, Diviès C. Cloning and sequencing of the gene encoding alpha-acetolactate decarboxylase from Leuconostoc oenos. FEMS Microbiol Lett 1996; 145:445-50. [PMID: 8978099 DOI: 10.1111/j.1574-6968.1996.tb08614.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The alsD gene encoding alpha-acetolactate decarboxylase was isolated from a genomic library of Leuconostoc oenos, using a screening procedure developed on microtiter plates. The nucleotide sequence of alsD encodes a putative protein of 239 amino acids showing significant similarity with other bacterial alpha-acetolactate decarboxylases. Upstream from alsD lies an open reading frame (alsS) which is highly similar to bacterial genes coding for catabolic alpha-acetolactate synthases. Northern (RNA) blotting analyses indicated the presence of a 2.4-kb dicistronic transcript of alsS and alsD. This suggests that the alsS and alsD genes are organized in a single operon.
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Affiliation(s)
- D Garmyn
- Laboratoire de Microbiologie, ENSBANA, Université de Bourgogne, Dijon, France.
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Boumerdassi H, Desmazeaud M, Monnet C, Boquien C, Corrieu G. Improvement of Diacetyl Production by Lactococcus lactis ssp. lactis CNRZ 483 Through Oxygen Control. J Dairy Sci 1996. [DOI: 10.3168/jds.s0022-0302(96)76425-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Llauro MF, Monnet C, Goux A, Spitz R, Hamaide T. 13C-NMR of Anionic Low-Molecular-Weight Stat-Poly(Ethylene Oxide-Co-Propylene Oxide): Correlation with Monte Carlo Simulation. International Journal of Polymer Analysis and Characterization 1995. [DOI: 10.1080/10236669508233870] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Monnet C, Schmilt P, Divies C. Diacetyl Production in Milk by an α-Acetolactic Acid Accumulating Strain of Lactococcus lactis ssp. lactis biovar. diacetylactis. J Dairy Sci 1994. [DOI: 10.3168/jds.s0022-0302(94)77232-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Phalip V, Monnet C, Schmitt P, Renault P, Godon JJ, Diviès C. Purification and properties of the alpha-acetolactate decarboxylase from Lactococcus lactis subsp. lactis NCDO 2118. FEBS Lett 1994; 351:95-9. [PMID: 8076701 DOI: 10.1016/0014-5793(94)00820-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
alpha-Acetolactate decarboxylase from Lactococcus lactis subsp. lactis NCDO 2118 was expressed at low levels in cell extracts and was also unstable. The purification was carried out from E. coli in which the enzyme was expressed 36-fold higher. The specific activity was 24-fold enhanced after purification. The main characteristics of alpha-acetolactate decarboxylase were: (i) activation by the three branched chain amino acids leucine, valine and isoleucine; (ii) allosteric properties displayed in absence and Michaelis kinetics in the presence of leucine. The enzyme is composed of six identical subunits of 26,500 Da.
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Affiliation(s)
- V Phalip
- Laboratoire de Microbiologie, ENS.BANA, Dijon, France
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Monnet C, Schmitt P, Divies C. Method for Assaying Volatile Compounds by Headspace Gas Chromatography and Application to Growing Starter Cultures. J Dairy Sci 1994. [DOI: 10.3168/jds.s0022-0302(94)77122-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Mérand V, Forest E, Gagnon J, Monnet C, Thibault P, Neuburger M, Douce R. Characterization of the primary structure of H-protein from Pisum sativum and location of a lipoic acid residue by combined liquid chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry. Biol Mass Spectrom 1993; 22:447-56. [PMID: 8357858 DOI: 10.1002/bms.1200220805] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A purified extract of H-protein, a subunit of the glycine cleavage complex of the pea leaf mitochondria, was investigated by liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS), using both continuous flow fast atom bombardment (CF-FAB) and electrospray ionization (ESI) mass spectrometry. Determination of the molecular weight of the entire protein, a 14 kDa subunit of the glycine decarboxylase complex, was achieved by ESI mass spectrometry and revealed covalent binding of the protein to the stabilizing agent beta-mercapto-ethanol. On-line LC/MS analysis of peptides arising from the endoproteinase Glu-C digestion of the H-protein was achieved using capillary columns (0.25 mm i.d.), and permitted confirmation of the previously reported sequence deduced from cDNA cloning experiments. The detailed interpretation of data extracted from these LC/MS experiments facilitated identification of peptides containing modified amino acid residues. In particular the identification of a lipoic acid cofactor, a rather unusual modified lysine residue which interacts with different active sites in the enzyme complex, was achieved using both LC/CF-FAB-MS and LC/ESI-MS. The exact location of this modified lysine residue was determined by obtaining fragment spectra of multiply protonated precursor ions of selected peptides, using on-line LC/MS/MS techniques.
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Affiliation(s)
- V Mérand
- Institut de Biologie Structurale, Grenoble, France
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Cruz-Rivera A, Rios-Guerrero L, Monnet C, Schlund B, Guillot J, Pichot C. Structure-property relationships in styrene-butyl acrylate emulsion copolymers: 1. Preparation and characterization of latexes. POLYMER 1989. [DOI: 10.1016/0032-3861(89)90361-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Monnet C, Bacin F, Lumbroso P, Guyot M. [Arion's thread: indications and results (study of 27 treated cases)]. Bull Soc Ophtalmol Fr 1979; 79:637-41. [PMID: 546560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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