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Wang M, Asam S, Chen J, Ehrmann M, Rychlik M. Production of Four 15N-Labelled Cobalamins via Biosynthesis Using Propionibacterium freudenreichii. Front Microbiol 2021; 12:713321. [PMID: 34484151 PMCID: PMC8414983 DOI: 10.3389/fmicb.2021.713321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 07/19/2021] [Indexed: 11/18/2022] Open
Abstract
Cobalamins (vitamin B12) are required by humans for their essential roles as enzyme cofactors in diverse metabolic processes. The four most common cobalamin vitamers are hydroxocobalamin (OHCbl), adenosylcobalamin (AdoCbl), methylcobalamin (MeCbl), and cyanocobalamin (CNCbl). Humans are not able to synthesise cobalamins de novo and thus must acquire them from external sources. Therefore, a reliable and robust analytical method to determine the cobalamins in dietary sources is highly required. For such a purpose, stable isotope dilution assays (SIDAs) with LC-MS/MS are most suited due to their superior sensitivity, specificity, and ability to compensate for matrix effects and analyte loss during sample work-up. However, a critical bottleneck for developing a SIDA method for cobalamins is the availability of stable isotope-labelled internal standards. In the present study, we harnessed the potential of Propionibacterium (P.) freudenreichii for the biosynthesis of 15N-labelled cobalamins. First, we developed a chemically defined medium (CDM) containing ammonium sulphate as a single nitrogen source except three essential vitamins that supported long-term stable growth of P. freudenreichii throughout continuous transfers. The CDM was further optimised for cobalamin production under different incubation schemes. With the optimised CDM and incubation scheme, fully 15N-labelled cobalamins were obtained in P. freudenreichii with a final yield of 312 ± 29 μg/L and 635 ± 102 μg/L, respectively, for [15N]-OHCbl and [15N]-AdoCbl. Additionally, an optimised incubation process under anaerobic conditions was successfully employed to produce specifically labelled [15N, 14N2]-cobalamins, with a yield of 96 ± 18 μg/L and 990 ± 210 μg/L, respectively, for [15N, 14N2]-OHCbl and [15N, 14N2]-AdoCbl. The labelled substances were isolated and purified by solid phase extraction and semi-preparative HPLC. Chemical modifications were carried out to produce [15N]-CNCbl and [15N]-MeCbl. Eventually, 15N-labelled compounds were obtained for the four cobalamin vitamers in high chromatographic and isotopic purity with desired 15N-enrichment and labelling patterns, which are perfectly suited for future use in SIDAs or other applications that require isotopologues.
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Affiliation(s)
- Mengle Wang
- Chair of Analytical Food Chemistry, Technical University of Munich, Freising, Germany
| | - Stefan Asam
- Chair of Analytical Food Chemistry, Technical University of Munich, Freising, Germany
| | - Jianqi Chen
- Chair of Analytical Food Chemistry, Technical University of Munich, Freising, Germany
| | - Matthias Ehrmann
- Chair of Technical Microbiology, Technical University of Munich, Freising, Germany
| | - Michael Rychlik
- Chair of Analytical Food Chemistry, Technical University of Munich, Freising, Germany
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Characterization and Transcriptome Studies of Autoinducer Synthase Gene from Multidrug Resistant Acinetobacter baumannii Strain 863. Genes (Basel) 2019; 10:genes10040282. [PMID: 30965610 PMCID: PMC6523755 DOI: 10.3390/genes10040282] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 03/15/2019] [Accepted: 03/15/2019] [Indexed: 01/17/2023] Open
Abstract
Quorum sensing (QS) is a cell-to-cell communication system that uses autoinducers as signaling molecules to enable inter-species and intra-species interactions in response to external stimuli according to the population density. QS allows bacteria such as Acinetobacter baumannii to react rapidly in response to environmental changes and hence, increase the chances of survival. A. baumannii is one of the causative agents in hospital-acquired infections and the number of cases has increased remarkably in the past decade. In this study, A. baumannii strain 863, a multidrug-resistant pathogen, was found to exhibit QS activity by producing N-acyl homoserine lactone. We identified the autoinducer synthase gene, which we named abaI, by performing whole genome sequencing analysis of A. baumannii strain 863. Using high resolution tandem triple quadrupole mass spectrometry, we reported that abaI of A. baumannii strain 863 produced 3-hydroxy-dodecanoyl-homoserine lactone. A gene deletion mutant was constructed, which confirmed the functionality of abaI. A growth defect was observed in the QS-deficient mutant strain. Transcriptome profiling was performed to determine the possible genes regulated by QS. Four groups of genes that showed differential expression were discovered, namely those involved in carbon source metabolism, energy production, stress response and the translation process.
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Rabah H, Ferret-Bernard S, Huang S, Le Normand L, Cousin FJ, Gaucher F, Jeantet R, Boudry G, Jan G. The Cheese Matrix Modulates the Immunomodulatory Properties of Propionibacterium freudenreichii CIRM-BIA 129 in Healthy Piglets. Front Microbiol 2018; 9:2584. [PMID: 30420848 PMCID: PMC6215859 DOI: 10.3389/fmicb.2018.02584] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 10/10/2018] [Indexed: 12/15/2022] Open
Abstract
Propionibacterium freudenreichii is a beneficial bacterium, used as a cheese starter, which presents versatile probiotic properties. These properties are strain-dependent. We hypothesized they may also be delivery vehicle-dependent. In this study, we thus explored in healthy piglets how the cheese matrix affects the immunomodulatory properties of P. freudenreichii. During 2 weeks, three groups of weaned piglets consumed, respectively, P. freudenreichii as a liquid culture (PF-culture), P. freudenreichii under the form of a cheese (PF-cheese), or a control sterile cheese matrix (Cheese-matrix). The in vivo metabolic activity of P. freudenreichii was assessed by determining short chain fatty acids (SCFA) concentration and bifidobacteria population in feces. Whatever the delivery vehicle, P. freudenreichii was metabolically active in piglets' colon and enhanced both bifidobacteria and SCFA in feces. P. freudenreichii consumption decreased the secretion of TNFα and of IL-10 by peripheral blood mononuclear cells (PBMC). It did not alter IL-10, IFNγ, IL-17, and TNFα secretion in mesenteric lymph node immune cells (MLNC). PF-cheese enhanced significantly Treg phenotype, while PF-culture decreased significantly Th17 phenotype in PBMC and MLNC. Remarkably, only PF-cheese induced an increase of Th2 phenotype in PBMC and MLNC. Ex vivo stimulation of PBMC and MLNC by Lipopolysaccharides and Concanavalin A emphasized the difference in the immunomodulatory responses between PF-culture and PF-cheese group, as well as between PBMC and MLNC. This study shows the importance to consider the delivery vehicle for probiotic administration. It confirms the anti-inflammatory potential of P. freudenreichii. It opens new perspectives for the use propionibacteria-fermented products as preventive agents for inflammatory bowel diseases and intestinal infectious diseases.
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Affiliation(s)
- Houem Rabah
- STLO, INRA, Agrocampus Ouest, Rennes, France
- Pôle Agronomique Ouest, Rennes, France
| | | | - Song Huang
- STLO, INRA, Agrocampus Ouest, Rennes, France
| | - Laurence Le Normand
- INRA, INSERM, Univ Rennes, Nutrition Metabolisms and Cancer, NuMeCan, Rennes, France
| | | | - Floriane Gaucher
- STLO, INRA, Agrocampus Ouest, Rennes, France
- Bioprox, Levallois-Perret, France
| | | | - Gaëlle Boudry
- INRA, INSERM, Univ Rennes, Nutrition Metabolisms and Cancer, NuMeCan, Rennes, France
| | - Gwénaël Jan
- STLO, INRA, Agrocampus Ouest, Rennes, France
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Lactobacillus delbrueckii subsp. lactis as a starter culture significantly affects the dynamics of volatile compound profiles of hard cooked cheeses. Eur Food Res Technol 2017. [DOI: 10.1007/s00217-017-2899-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Strain-to-strain differences within lactic and propionic acid bacteria species strongly impact the properties of cheese–A review. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/s13594-015-0267-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Aunsbjerg S, Honoré A, Vogensen F, Knøchel S. Development of a chemically defined medium for studying foodborne bacterial–fungal interactions. Int Dairy J 2015. [DOI: 10.1016/j.idairyj.2015.01.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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de Freitas R, Madec MN, Chuat V, Maillard MB, Mukdsi MCA, Falentin H, de Carvalho AF, Valence F, Thierry A. New insights about phenotypic heterogeneity within Propionibacterium freudenreichii argue against its division into subspecies. ACTA ACUST UNITED AC 2015; 95:465-477. [PMID: 26097645 PMCID: PMC4471392 DOI: 10.1007/s13594-015-0229-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 04/08/2015] [Accepted: 04/09/2015] [Indexed: 02/07/2023]
Abstract
Propionibacterium freudenreichii is widely used in Swiss-type cheese manufacture, where it contributes to flavour and eye development. It is currently divided into two subspecies, according to the phenotype for lactose fermentation and nitrate reduction (lac+/nit− and lac−/nit+ for P. freudenreichii subsp. shermanii and subsp. freudenreichii, respectively). However, the existence of unclassifiable strains (lac+/nit+ and lac−/nit−) has also been reported. The aim of this study was to revisit the relevance of the subdivision of P. freudenreichii into subspecies, by confirming the existence of unclassifiable strains. Relevant conditions to test the ability of P. freudenreichii for lactose fermentation and nitrate reduction were first determined, by using 10 sequenced strains, in which the presence or absence of the lactose and nitrate genomic islands were known. We also determined whether the subdivision based on lac/nit phenotype was related to other phenotypic properties of interest in cheese manufacture, in this case, the production of aroma compounds, analysed by gas chromatography-mass spectrometry, for a total of 28 strains. The results showed that a too short incubation time can lead to false negative for lactose fermentation and nitrate reduction. They confirmed the existence of four lac/nit phenotypes instead of the two expected, thus leading to 13 unclassifiable strains out of the 28 characterized (7 lac+/nit+ and 6 lac−/nit−). The production of the 15 aroma compounds detected in all cultures varied more within a lac/nit phenotype (up to 20 times) than between them. Taken together, these results demonstrate that the division of P. freudenreichii into two subspecies does not appear to be relevant.
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Affiliation(s)
- Rosangela de Freitas
- Departamento de Tecnologia de Alimentos, Universidade Federal de Viçosa, Viçosa, MG Brazil ; INRA, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France ; AGROCAMPUS OUEST, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France
| | - Marie-Noelle Madec
- INRA, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France ; AGROCAMPUS OUEST, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France
| | - Victoria Chuat
- INRA, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France ; AGROCAMPUS OUEST, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France
| | - Marie-Bernadette Maillard
- INRA, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France ; AGROCAMPUS OUEST, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France
| | - María C Abeijón Mukdsi
- INRA, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France ; AGROCAMPUS OUEST, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France ; Centro de Referencia para Lactobacilos (CERELA-CONICET), Chacabuco 145, (4000), Tucumán, Argentina
| | - Hélène Falentin
- INRA, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France ; AGROCAMPUS OUEST, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France
| | | | - Florence Valence
- INRA, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France ; AGROCAMPUS OUEST, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France
| | - Anne Thierry
- INRA, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France ; AGROCAMPUS OUEST, UMR1253 Science et Technologie du Lait et de l'OEuf, 35042 Rennes, France
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Aunsbjerg S, Honoré A, Marcussen J, Ebrahimi P, Vogensen F, Benfeldt C, Skov T, Knøchel S. Contribution of volatiles to the antifungal effect of Lactobacillus paracasei in defined medium and yogurt. Int J Food Microbiol 2015; 194:46-53. [DOI: 10.1016/j.ijfoodmicro.2014.11.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 10/17/2014] [Accepted: 11/05/2014] [Indexed: 02/08/2023]
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Great interspecies and intraspecies diversity of dairy propionibacteria in the production of cheese aroma compounds. Int J Food Microbiol 2014; 191:60-8. [DOI: 10.1016/j.ijfoodmicro.2014.09.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 07/26/2014] [Accepted: 09/01/2014] [Indexed: 11/23/2022]
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Mikš-Krajnik M, Babuchowski A, Białobrzewski I. Impact of physiological state of starter culture on ripening and flavour development of Swiss-Dutch-type cheese. INT J DAIRY TECHNOL 2013. [DOI: 10.1111/1471-0307.12079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marta Mikš-Krajnik
- Chair of Industrial and Food Microbiology; Faculty of Food Science; University of Warmia and Mazury; Plac Cieszyński 1; 10-726; Olsztyn; Poland
| | - Andrzej Babuchowski
- Chair of Industrial and Food Microbiology; Faculty of Food Science; University of Warmia and Mazury; Plac Cieszyński 1; 10-726; Olsztyn; Poland
| | - Ireneusz Białobrzewski
- Chair of Systems Engineering; Faculty of Engineering; University of Warmia and Mazury; Heweliusza 14; 10-718; Olsztyn; Poland
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A temporal-omic study of Propionibacterium freudenreichii CIRM-BIA1 adaptation strategies in conditions mimicking cheese ripening in the cold. PLoS One 2012; 7:e29083. [PMID: 22253706 PMCID: PMC3258244 DOI: 10.1371/journal.pone.0029083] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 11/21/2011] [Indexed: 11/19/2022] Open
Abstract
Propionibacterium freudenreichii is used as a ripening culture in Swiss cheese manufacture. It grows when cheeses are ripened in a warm room (about 24°C). Cheeses with an acceptable eye formation level are transferred to a cold room (about 4°C), inducing a marked slowdown of propionic fermentation, but P. freudenreichii remains active in the cold. To investigate the P. freudenreichii strategies of adaptation and survival in the cold, we performed the first global gene expression profile for this species. The time-course transcriptomic response of P. freudenreichii CIRM-BIA1(T) strain was analyzed at five times of incubation, during growth at 30°C then for 9 days at 4°C, under conditions preventing nutrient starvation. Gene expression was also confirmed by RT-qPCR for 28 genes. In addition, proteomic experiments were carried out and the main metabolites were quantified. Microarray analysis revealed that 565 genes (25% of the protein-coding sequences of P. freudenreichii genome) were differentially expressed during transition from 30°C to 4°C (P<0.05 and |fold change|>1). At 4°C, a general slowing down was observed for genes implicated in the cell machinery. On the contrary, P. freudenreichii CIRM-BIA1(T) strain over-expressed genes involved in lactate, alanine and serine conversion to pyruvate, in gluconeogenesis, and in glycogen synthesis. Interestingly, the expression of different genes involved in the formation of important cheese flavor compounds, remained unchanged at 4°C. This could explain the contribution of P. freudenreichii to cheese ripening even in the cold. In conclusion, P. freudenreichii remains metabolically active at 4°C and induces pathways to maintain its long-term survival.
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Thierry A, Deutsch SM, Falentin H, Dalmasso M, Cousin FJ, Jan G. New insights into physiology and metabolism of Propionibacterium freudenreichii. Int J Food Microbiol 2011; 149:19-27. [DOI: 10.1016/j.ijfoodmicro.2011.04.026] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 04/14/2011] [Accepted: 04/29/2011] [Indexed: 01/25/2023]
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Cousin FJ, Mater DD, Foligne B, Jan G. Dairy propionibacteria as human probiotics: A review of recent evidence. ACTA ACUST UNITED AC 2010. [DOI: 10.1051/dst/2010032] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Falentin H, Deutsch SM, Jan G, Loux V, Thierry A, Parayre S, Maillard MB, Dherbécourt J, Cousin FJ, Jardin J, Siguier P, Couloux A, Barbe V, Vacherie B, Wincker P, Gibrat JF, Gaillardin C, Lortal S. The complete genome of Propionibacterium freudenreichii CIRM-BIA1, a hardy actinobacterium with food and probiotic applications. PLoS One 2010; 5:e11748. [PMID: 20668525 PMCID: PMC2909200 DOI: 10.1371/journal.pone.0011748] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Accepted: 06/29/2010] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Propionibacterium freudenreichii is essential as a ripening culture in Swiss-type cheeses and is also considered for its probiotic use. This species exhibits slow growth, low nutritional requirements, and hardiness in many habitats. It belongs to the taxonomic group of dairy propionibacteria, in contrast to the cutaneous species P. acnes. The genome of the type strain, P. freudenreichii subsp. shermanii CIRM-BIA1 (CIP 103027(T)), was sequenced with an 11-fold coverage. METHODOLOGY/PRINCIPAL FINDINGS The circular chromosome of 2.7 Mb of the CIRM-BIA1 strain has a GC-content of 67% and contains 22 different insertion sequences (3.5% of the genome in base pairs). Using a proteomic approach, 490 of the 2439 predicted proteins were confirmed. The annotation revealed the genetic basis for the hardiness of P. freudenreichii, as the bacterium possesses a complete enzymatic arsenal for de novo biosynthesis of aminoacids and vitamins (except panthotenate and biotin) as well as sequences involved in metabolism of various carbon sources, immunity against phages, duplicated chaperone genes and, interestingly, genes involved in the management of polyphosphate, glycogen and trehalose storage. The complete biosynthesis pathway for a bifidogenic compound is described, as well as a high number of surface proteins involved in interactions with the host and present in other probiotic bacteria. By comparative genomics, no pathogenicity factors found in P. acnes or in other pathogenic microbial species were identified in P. freudenreichii, which is consistent with the Generally Recognized As Safe and Qualified Presumption of Safety status of P. freudenreichii. Various pathways for formation of cheese flavor compounds were identified: the Wood-Werkman cycle for propionic acid formation, amino acid degradation pathways resulting in the formation of volatile branched chain fatty acids, and esterases involved in the formation of free fatty acids and esters. CONCLUSIONS/SIGNIFICANCE With the exception of its ability to degrade lactose, P. freudenreichii seems poorly adapted to dairy niches. This genome annotation opens up new prospects for the understanding of the P. freudenreichii probiotic activity.
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Affiliation(s)
- Hélène Falentin
- INRA, UMR 1253, Science et Technologie du Lait et de l'OEuf, Rennes, France.
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Schreiberová O, Krulikovská T, Sigler K, Čejková A, Řezanka T. RP-HPLC/MS-APCI Analysis of Branched Chain TAG Prepared by Precursor-Directed Biosynthesis with Rhodococcus erythropolis. Lipids 2010; 45:743-56. [DOI: 10.1007/s11745-010-3447-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 06/29/2010] [Indexed: 10/19/2022]
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Identification of a secreted lipolytic esterase in Propionibacterium freudenreichii, a ripening process bacterium involved in Emmental cheese lipolysis. Appl Environ Microbiol 2009; 76:1181-8. [PMID: 20038704 DOI: 10.1128/aem.02453-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lipolysis plays an important role in the formation of cheese flavor. In Emmental cheese, the main part of lipolysis has been associated with the presence of Propionibacterium freudenreichii, a species used as a ripening culture. Our aim was to identify the most probable lipolytic esterase(s) involved in cheese lipolysis by P. freudenreichii. Since cheese lipolysis mainly occurs during P. freudenreichii growth, we hypothesized that P. freudenreichii possesses secreted lipolytic esterase(s). For 12 putative esterase genes previously identified from the genome of P. freudenreichii CIRM1, the level of expression was quantified by real-time reverse transcriptase (RT)-PCR, and the subcellular localization of esterases was predicted in silico. The esterase activity in extracellular and intracellular extracts of P. freudenreichii was characterized by zymography, and the extracellular esterases were identified by mass spectrometry. Finally, the best candidate was overexpressed in the same strain. All of the 12 genes encoding putative esterases were expressed. Esterase PF#279 was predicted to be secreted in the medium, PF#774 to be surface exposed, and the 10 remaining putative esterases to be intracellular. Zymography revealed that esterase activities in culture supernatant differed from the ones detected in intracellular extracts. PF#279 was identified as the sole esterase present in culture supernatant. Transformed P. freudenreichii CIRM1 clones overexpressing PF#279 showed 5 to 8 times more lipolytic activity on milk fat than the wild-type strain. Combining in silico, biochemical, and genetic approaches, we showed that PF#279 is the sole secreted esterase in P. freudenreichii and is active on milk fat. Therefore, it is likely a key component in cheese lipolysis by P. freudenreichii.
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