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International audience; Swiss cheeses have been produced for centuries in a traditional way and their typical opening indicates the presence of propionibacteria. These last are indeed present in raw milk, their growth is favored by the specific technology of Swiss-type cheeses, and their high population in the ripened cheese is responsible for its characteristic sensory properties, including the opening and the aroma. In addition to this long history of safe use and consumption, they constitute a source of nutraceuticals. The specific propionic fermentation leads to the production of short chain fatty acids as main final obligatory products. These exert beneficial effects including nourishment of digestive epithelial cells, as well as promotion of differentiation and of apoptotic depletion of colon cancer cells. Propionibacteria also produce vitamins of the B group, which enhances the nutritional value of the food products they ferment. Some selected strains were moreover shown to produce immunomodulins, proteins able to modify the secretion of cytokines in human immune cells. These last were identified as proteinaceous components of propionibacteria surface layer. They also produce extracellular vesicles which modulate in vitro inflammation and the NFκB pathway in human intestinal epithelial cells. Accordingly, such strains modulate the immune response and mitigate inflammation. In mice, they prevent both mucositis and colitis, via such immunomodulins limiting acute inflammatory response and protecting the gut epithelial barrier. In pigs, their consumption also modulates the inflammatory response and the lymphocyte populations. Finally, clinical studies dealing with consumption of propionibacteria whey cultures suggest a beneficial role in the context of IBD. Propionibacteria strains were recently identified in the gut microbiota of healthy newborns, yet not in that of children with necrotizing enterocolitis. Indeed, propionibacteria were detected in human fecal samples, which means that propionibacteria may be traditional cheese starters or next generation probiotics. The growing knowledge of these peculiar actinobacteria, including their great strain-diversity, opens new avenues for the development of functional foods and of food supplements, in a general context of increasing incidence of ailments that include an inflammatory component. Moreover, their ability to ferment both dairy and vegetable matrices is presently investigated and the first promising advances open new perspectives for the development of functional fermented vegetable products.

International audience; IntroductionGut inflammation constitutes a growing health concern in developed countries. It may consist in spontaneous ailments of the gut, involving both the host immune system and microbiota, such as IBD, including ulcerative colitis and Crohn’s disease. It may be caused by a medical treatment, such as mucositis induced by cancer chemotherapy and/or radiotherapy. It coincides with a dysbiosis including a lack of anti-inflammatory bacteria. As an example, propionibacteria are lacking in the microbiota of newborns that develop necrotizing enterocolitis.Methods Dairy propionibacteria strains were tested in vitro on human PBMCs with respect to their ability to induce immunomodulatory cytokines. Selected strains were then tested in vitro with respect to their ability to protect mice from TNBS-induced colitis, from DSS-induced colitis, and from 5FU-induced mucositis.ResultsWe thus focused on the immunomodulatory properties of GRAS propionibacteria. Selected strains of Propionibacterium freudenreichii induced the regulatory IL-10 cytokine in human immune cells (Foligné et al., 2010, 2013), depending on surface proteins (Le Marechal et al., 2015). Mutation of the slpB gene suppressed this immunomodulatory effect and the resulting slpB mutant induced a rather proinflammatory response (Deutsch et al., 2017). Consumption of wild-type P. freudenreichii protected from colitis induced by both TNBS and by DSS. It alleviated severity of symptoms, modulated local and systemic inflammation, as well as colonic oxidative stress and epithelial cell damages (Plé et al., 2015, 2016; Rabah et al., 2020). Accordingly, consumption of Lactococcus lactis NCDO 2118 harboring pXIES-SEC:slpB and expressing the propionibacterial SlpB reduced severity of colitis, lowered weight loss, disease activity index, shortening of the colon length, and histopathological score, compared with mice treated with L. lactis NCDO 2118 wild-type strain (Belo et al., 2021).In the context of mucositis induced by the chemotherapy 5-FU, P. freudenreichii prevented weight loss, reduced inflammation and consequently intestinal damages. It regulated key markers, including Claudin-1 and IL-17a genes, as well as IL-12 and IL-1β cytokines levels (Cordeiro et al., 2018). Mutant strain slpB displayed opposite regulatory effect on cld1 expression and on IL-12 levels, and failed to afford protection towards 5-FU-mucositis (do Carmo et al., 2019).P. freudenreichii was further shown to produce extracellular vesicles (EVs), which mimic the immunomodulatory features of propionibacteria in vitro by modulating NF-κB transcription factor activity and IL-8 release in cultured human intestinal epithelial cells (Rodovalho et al., 2020). Proteomic analysis revealed presence of SlpB in these EVs.DiscussionThis work emphasizes the importance of SlpB in P. freudenreichii ability to reduce both mucositis and colitis inflammation. It opens perspectives for the development of probiotic products aimed at decreasing side effects of chemotherapy and at helping treatment of colitis, thanks to GRAS bacteria.

International audience; L’intégrité de la barrière épithéliale intestinale (BEI) joue un rôle central dans la pathogenèse des maladies inflammatoires chroniques de l’intestin (MICI). Un intérêt grandissant est porté aux composés alimentaires capables de renforcer ou de restaurer la BEI. C’est le cas de souches de Propionibacterium freudenreichii, une bactérie propionique laitière, capable de restaurer la BEI fragilisée dans un contexte inflammatoire. Egalement, il existe une protection locale de la BEI exercée par les produits du métabolisme des acides gras polyinsaturés oméga-6 (AGPI n-6) par les cellules intestinales. Les omégas 6 sont apportés par l’alimentation, dont le lait. Les enzymes de leur métabolisme sont sous-exprimés chez les patients atteints de MICI, empêchant l’action bénéfique d’une supplémentation en AGPI n-6 chez ces patients. L’augmentation de la biodisponibilité des dérivés AGPI n-6 reste une piste intéressante. Par ailleurs, certaines souches de P. freudenreichii, sont capables de convertir l’acide linoléique, un AGPI n-6, en acide linoléique conjugué (ALC), capable de prévenir des colites induites chez des souris. Ces souches pourraient donc moduler la biodisponibilité et le métabolisme des AGPI n-6. Notre objectif vise à rechercher des effets additifs voire synergiques entre l’effet de 1) P. freudenreichii et 2) des AGPI n-6 sur la BEI. Un criblage de trente-trois souches de P. freudenreichii a été réalisé basé sur les critères suivants : 1) caractérisation de la capacité à induire la production de cytokines anti-inflammatoire (IL-10) par stimulation de PBMCs humaines 2) identification de protéines de surface (S-layer protein) responsable des propriétés anti-inflammatoire par une technique de rasage enzymatique suivis d’une identification par MS/MS 3) mesure de l’activité lipolytique dans la matière grasse laitière et de la conversion de l’acide linoléique en ALC avec une identification des lipides par GC-MS. Toutes les souches sont capables d’induire la production d’IL-10. Seulement, la puissance d’induction d’IL-10 est souche dépendante. Sur les trente-trois souches, dix présentent un profil S-layer anti-inflammatoire. Toutes les souches sont capables de lipolyser la matière grasse laitière, certaines produisent de l’acide linoléique. Toutes les souches exceptées une, sont capable de convertir l’acide linoléique en ALC. De façon similaire aux profils des cytokines, la production d’ALC est souche dépendante. Ces résultats apportent de nouvelles connaissances sur P. freudenreichii, et vont permettre sélectionner des souches qui, ayant un potentiel anti-inflammatoire ainsi que pro-réparateur, seront testées in vivo pour réduire la colite, avec ou sans supplémentation en AGPI n-6.

International audience; Introduction and Aims. Inflammatory Bowel Diseases (IBD), including Ulcerative Colitis (UC), coincide with alterations in the gut microbiota. Consumption of immunomodulatory strains of probiotic bacteria may induce or prolong remission in UC patients. Fermented foods, including cheeses, constitute major vectors for bacteria consumption. New evidences revealed anti-inflammatory effects of selected strains within the species P.freudenreichii, S.thermophilus and L.delbrueckii. We thus hypothesized that consumption of a functional cheese, fermented by selected strains of these three species, may exert a positive effect on IBD.Methods. Strains of each bacterial species were screened based on the ability to induce regulatory IL-10 in human immune PBMC cells, or to downregulate nuclear factor kappa B (NF-κB) activation in a cultured HT-29 human intestinal epithelial cell line. We then investigated the effect of monostrain experimental cheese. We further investigated the impact two-strains experimental cheese. Finally, we produced in industrial conditions an Emmental cheese using one selected strain of each of the three species, i.e. P. freudenreichii CIRM-BIA 129 in combination with Lactobacillus delbrueckii CNRZ327 and Streptococcus thermophilus LMD-9. Consumption of all cheeses was investigated with respect to prevention of chemically induced colitis in mice.Results. Consumption of the experimental cheeses, or of the industrial Emmental, reduced the severity of subsequent chemically induced colitis, weight loss, disease activity index and histological score, in mice. Furtherrmore, consumption of the Emmental cheese, in a preventive way, reduced small bowel Immunoglobulin A (IgA) secretion, restored occludin gene expression and prevented induction of Tumor Necrosis Factor α (TNFα), Interferon γ (IFNγ) and Interleukin-17 (IL-17).Conclusion. Assembling immunomodulatory strains of both lactic acid and propionic acid starter bacteria leads to an anti-inflammatory Emmental cheese, as revealed in vivo. This opens new perspectives for the development of functional fermented food products for personalised nutrition in the context of IBD.

International audience; Cheeses exist since ancient times and are still a matter of discovery, as well as a source of innovation. Originally designed to preserve milk, their culture- and tradition-driven technology led to the empirical selection of domesticated microbial consortia. Science has later deciphered, cultivated and characterized the members of such dedicated consortia. Microbial strains can now be selected based on both technological and probiotic criteria. Beyond the traditions and the expected hedonic perceptions, the keystones of the current changes in cheese technology are indeed the way cheeses are made, the way starters are selected and conserved as well as how the cheeses are destructured in the digestive tract, according to specific population. Here we describe our advances in these different research areas and the emerging trends for future. The selection of strains of lactic acid bacteria and of propionibacteria, each combining cheese-making and probiotic skills, leads to the production of functional cheeses, in which the dairy matrix constitutes a protective delivery vehicle for immunomodulatory components. This is illustrated in the context of colitis, i.e. gut inflammation.Cheeses enriched in whey proteins, fermented with selected starters, fulfil the requirements of elderly towards essential aminoacids.Uncoupling the 2 major steps of cheese making, texturing through protein concentration, and flavouring through microbial fermentation, allows quick, safe and sustainable production of “high-tech” cheeses with reduced energy consumption and reduced coproducts production.Incorporation of vegetable proteins, and of microbes able to process them, into the cheese-making process, leads to innovative cheeses with a reduced ecological impact.All these innovations open new avenues for the development of designer cheeses adapted to evolving needs of specific populations and addressing growing ethical concerns.

International audience; Introduction Propionibacterium freudenreichii, is a probiotic bacterium, with an established immunomodulatory role. Selected strains indeed induce the release of regulatory IL-10. Extractable surface proteins of the S-layer type (Slp) are involved in such modulation, but the exact mode of interaction with the host remains unknown. Mucositis is a common side effect of cytotoxic chemotherapy characterized by mucosal injury, inflammation, diarrhea, and weight loss. We hypothesized that immunomodulatory P. freudenreichii may mitigate inflammation and that SlpB may be required for such an effect.Extracellular vesicles (EVs) are nanometric spherical structures involved in intercellular communication, whose production is considered a widespread phenomenon in living organisms. Bacterial EVs are associated with several processes that include survival, competition, pathogenesis, and immunomodulation. We hypothesized that, in addition to surface exposure and secretion of proteins, P. freudenreichii may produce EVs and thus export immunomodulatory proteins to interact with the host.MethodsP. freudenreichii CIRM-BIA 129, previously selected for its ability to induce IL-10 release by PBMCs, was administered orally to mice, prior to colitis induction using TNBS.The slpB gene was inactivated by insertional inactivation. Both parental wild type and mutant strains were administered orally to mice, prior to induction of mucositis using 5-FU. The SlpB protein was purified and its effect on cultured human intestinal epithelial cells investigated with respect to cytokines expression.EVs were purified from cell-free culture supernatants of the probiotic strain P. freudenreichii CIRM-BIA 129, prior to physicochemical and functional characterization.ResultsConsumption of P. freudenreichii CIM-BIA129 strain protected mice against TNBS-induced colitis in mice, alleviating severity of symptoms, modulating local and systemic inflammation, as well as colonic oxidative stress and epithelial cell damages.This strain prevented 5-FU-induced mucositis in mice, regulated key markers, including the expression of Claudin-1 (Cld1) and IL-17a (Il17a), as well as the levels of IL-12 and IL-1β cytokines.The slpB gene was mutated by insertional inactivation and the absence of SlpB protein in the resulting mutant was verified. The mutant strain displayed opposite immunomodulatory effect and failed to mitigate induced mucositis.In HT-29 human intestinal epithelial cells P. freudenreichii reduced expression of IL-8 and TNF-α cytokines in LPS-stimulated cells. P. freudenreichii ΔslpB, lacking the SlpB protein, failed to do so. In the same cells, purified SlpB was shown to induce expression of IL-10 in a dose-dependent manner.Extracellular vesicles (EVs), they were purified from cell-free culture supernatants of P. freudenreichii. They showed typical shapes and sizes of EVs and contained a broad range of proteins, including SlpB. EVs modulated inflammatory responses, IL-8 release and NF-κB activity, in HT-29 human intestinal epithelial cells, as well as the NF-κB pathway.DiscussionThis work emphasizes the importance of SlpB in immunomodulatory P. freudenreichii. It constitutes the first report on identification of P. freudenreichii-derived EVs, alongside their physicochemical, biochemical and functional characterization. It opens perspectives for the development of functional foods and other bioactive products in order to help preventing and/or treating inflammatory diseases, and to decrease side effects of chemotherapy.

La texture des aliments, leur densité contribuent à protéger les bactéries qui viendront enrichir notre flore intestinale. Démonstration avec l’emmental.

Genomic evidence has led to the division of genus Propionibacterium into Propionibacterium and Acidipropionibacterium. They are pleomorphic rods, anaerobic to aerotolerant, mesophilic, Gram-positive and of high G+C. They produce propionic acid as a major end product from many substrates. P. freudenreichii is used as ripening culture in Swiss-type cheeses, where it produces propionic and acetic acid, CO2 and aroma compounds leading to the characteristic flavor and eyes. They also produce vitamins and other compounds of interest and may be used as probiotics. Genetic tools and genome sequences are now available for both Propionibacterium and Acidipropionibacterium genera, which will improve their applications.

National audience

Le laboratoire UMR STLO vise à développer une expertise publique sur les composants du lait et de l’œuf et à augmenter la qualité et la sécurité des produits laitiers fermentés, via notamment l’isolement et la caractérisation de souches de bactéries bénéfiques d’intérêt alimentaire. L’une des approches consiste à exploiter les propriétés « 2-en-1 » de certaines souches, c’est-à-dire leurs propriétés techno-fonctionnelles (élaboration de produits laitiers fermentés aux caractéristiques désirées) ainsi que leurs propriétés probiotiques. Certaines bactéries mises en œuvre dans l’élaboration de produits laitiers fermentés peuvent en effet exercer un effet bénéfique sur la santé de l’homme.Les bactéries propioniques laitières, dont P. freudenreichii, sont responsables de l’ouverture et de l’arôme caractéristique de l’Emmental, via la production de CO2 et des acides gras à chaîne courte acétate et propionate. Ces derniers sont à l’origine de l’aptitude de P. freudenreichii à moduler la prolifération et l’apoptose, au niveau de cellules épithéliales digestives. Ainsi, la bactérie, un produit laitier fermenté par cette bactérie, ainsi que ses métabolites, induisent le scénario suivant, au contact de cellules cancéreuses gastriques ou intestinales. Arrêt du cycle cellulaire, dépolarisation des mitochondries, accumulation d’espèces réactives de l’oxygène, déplétion de l’ATP, fragmentation en corps apoptotiques, autant de paramètres qui ont été suivis par cytométrie en flux.Les bactéries propioniques laitières, dont P. freudenreichii, ont une composition de surface (surfaceome) extrêmement variable, d’une souche à l’autre. De même, leur capacité à adhérer aux cellules de l’hôte et leur capacité immunomodulatrice, deux paramètres intimement liés, sont variables. Les protéines de surface impliquées dans ce type d’interactions ont été étudiées par une approche pluridisciplinaire combinat génomique, transcriptomique, protéomique et cytométrie en flux. Ainsi, une protéine de la famille des Surface Layer Proteins (Slp), SlpB, s’est révélée cruciale dans le dialogue entre P. freudenreichii et l’hôte.Ces travaux ouvrent de nouvelles perspectives dans le domaine du développement d’aliments sains, sûrs, hédoniques et fonctionnels (bactéries lactiques et propioniques) issus de la fermentation du lait. Ils peuvent aider, en complément des traitements existants, à prévenir et/ou à soigner des pathologies (cancers, maladies inflammatoires chroniques) dont l’incidence croit dans les pays développés comme le nôtre.

International audience

Smart design of functional fermented dairy foods . STLOpendays

Probiotic microorganisms may affect human health, partly by modulating the immune response. They are commensals, part of the natural human microbiota, or provided within fermented foods or within food supplements. As an example, some of them colonize the digestive tract at early stages of life and play a key role in the maturation of the immune system. Accordingly, a lack of implantation of these beneficial bacteria correlates with immune and inflammatory disorders, which constitute a growing health concern and are gradually understood, in the light of variations of the gut microbiota structure. Potential applications of probiotic bacteria further involve the treatment of diarrhoea caused by rotavirus, of allergy, of eczema, of irritable bowel syndrome and of inflammatory bowel diseases. The mechanisms underlying interactions between probiotic bacteria and the host thus constitute a hot topic. Surface molecules of probiotic bacteria play a central role in these interactions. Referred to as Microbe-associated Molecular Pattern (MAMP), these key molecules are recognized by corresponding pattern recognition receptors (PRR), present at the surface of the host cells. The role of MAMPs includes adhesion and modulation of the gut associated immune system, prior to that of the systemic immune system, by mediating a host/bacteria cross-talk. MAMPs include surface proteins, glycoproteins, lipoproteins, pilins, flagellins, as well as surface associated polysaccharides. Host PRRs, which can perceive MAMPs, include Toll-like receptors (TLR), as well as the C type lectin DC-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN). They may be present at the surface of epithelial cells, and of dendritic cells. This oral presentation will illustrate the key role of probiotics’ MAMPs through examples of bifidobacteria, lactobacilli, and of propionibacteria. It will present textbook cases spanning from molecular to in vivo studies. Scientific data acquired during the last decade indeed place interactions between MAMP and PRR at the Centre of Probiotic/Host Interaction. The corresponding mechanisms are currently elucidated.

International audience; Introduction Propionibacterium freudenreichii (PF) is a beneficial bacterium, used as Swiss-type cheeses starter. PF exerts several beneficial effects, including anti-inflammatory modulation. This feature relies on several metabolites and on surface proteins. PF emerges as a suitable candidate to develop fermented functional foods. As it is established, the probiotic properties are strain-dependent, however the delivery vehicle effect is barely explored. Aim In this study, our purpose is to explore how the cheese matrix impact its immunomodulatory properties on model of healthy piglets. Methods Three groups of weaned piglets were fed during 2 weeks with PF in form of a culture or of a fermented cheese and compared to a control group fed with sterile cheese. PF’s metabolic activity was assessed by short chain fatty acids dosage and microbiota modulation. Immune cells from small intestinal mesenteric nodes (MLNC) and blood (PBMC) were extracted. The basal cytokines secretion and T lymphocytes phenotypes were evaluated. Then, the immune cells were ex vivo stimulated by pro-inflammatory and anti-inflammatory stimuli and the cytokine response was determined. Results PF was metabolically active in piglets’ colon and enhanced bifidobacteria population and SCFAs production, without significant difference between the two delivery vehicles. PF decreased the secretion of TNFα and IL-10 secretion only by PBMC. In MLNC, PF cheese enhanced Treg and Th2 populations and sustained Th17 population. PF culture enhanced decreased Th17 population in MLNC. In PBMC, PF ingestion enhanced Treg and Th2 populations, without difference between the two delivery vehicles. Ex vivo stimulation of PBMC and MLNC showed a difference in immunomodulation of PF, according the delivery vehicle. Conclusion These results provide new insights into the cheese matrix effect on P. freudenreichii' probiotic functionalities. Such data showed the relevance to take in account the delivery vehicle to develop functionnal foods.

IntroductionP. freudenreichii est utilisé comme ferment pour les fromages de type emmental et également comme probiotique. La stabilisation de P. freudenreichii sous forme de poudre est essentielle pour garantir une bonne stabilité. La lyophilisation et le séchage par atomisation peuvent être utilisés pour produire des ferments et des probiotiques en poudre. Le séchage par atomisation demande moins d’énergie que la lyophilisation. Cependant le séchage par atomisation expose les bactéries à de très hautes températures. Ce séchage est donc un procédé stressant, provocant des stress thermique, oxydatif et osmotique. En vue de résister à ce procédé, les bactéries doivent donc être adaptées. Les milieux de culture sont un moyen d’adapter les bactéries dans le but d’augmenter leur survie au séchage par atomisation.ObjectifDans cette étude, nous avons exploré l’influence de la composition du milieu de culture sur 1) l’accumulation d’osmoprotecteurs et 2) la survie des bactéries lors du séchage par atomisation.Matériels et méthodesPour le milieux riche YEL (Yeast Exctract Lactate) et les milieux laitiers, les concentrations de sel les plus élevées permettant la croissance de P. freudenreichii ont été choisies. Les osmoprotecteurs accumulés par P. freudenreichii ont été identifiés et quantifiés par RMN du proton et du carbone. Les différentes cultures ont ensuite subi les challenges oxydatifs, thermique et le séchage par atomisation.RésultatsPendant la croissance, P. feudenreichii CIRM-BIA 129 accumulent du tréhalose, du glutamate et de la glycine betaine. En condition hyper osmotique, l’accumulation de ces osmoprotecteurs est plus élevés. Le lactose naturellement présent dans le lactosérum, ou ajouté dans le YEL, provoque une adaptation au stress acide, mais augmente également l’accumulation intracellulaire du tréhalose. Le ratio tréhalose/glycine betaine accumulés est déterminé par le ratio azote/carbone du milieu de culture. Avec un ratio tréhalose/glycine betaine optimisé, P. freudenreihcii a une meilleure survie au challenge thermique et oxydatif, comme au séchage par atomisation.ConclusionPiloter la composition du milieu de culture de P. freudenreichii permet de diriger l’adaptation et conduit à une meilleure survie durant le séchage par atomisation. Ceci permettra par la suite la production de qualité des ferments et probiotiques avec de hauts rendement.

National audience; Introduction Inflammatory bowel disease (IBD) constitute a growing public health concern in western countries. More generally, inflammation is a key parameter involved in many non-communicable chronic diseases. Bacteria with anti-inflammatory properties are lacking in the dysbiosis accompanying IBD. Selected strains of probiotic bacteria with anti-inflammatory properties accordingly alleviate symptoms and enhance treatment of ulcerative colitis in clinical trials. Such properties are also found in (only) selected strains of dairy starters, including the Propionibacterium freudenreichii and Lactobacillus delbrueckii species, which are widely ingested. We thus investigated the possibility to develop a fermented dairy product, combining both starter and probiotic abilities of both lactic acid and propionic acid bacteria, designed to extend remissions in IBD patients. Methods We developed a single-strain L. delbrueckii-fermented milk and a two-strain P. freudenreichii and L. delbrueckii-fermented experimental pressed cheese using strains previously selected for their anti-inflammatory properties. This cheese was made in fully mastered conditions and contained only the two selected strains. It was consumed daily by mice during five days before induction of acute colitis by trinitrobenzenesulfonic acid (TNBS). Outcomes of colitis induction were then monitored in mice consuming this cheese or a placebo diary matrix. Results For the first time, consumption of a designer P. freudenreichii and Lactobacillus delbrueckii pressed cheese was shown to protect mice against experimental colitis, alleviating severity of symptoms, modulating local and systemic inflammation, as well as colonic oxidative stress and epithelial cell damages. As a control, the corresponding sterile dairy matrix failed to afford such protection. Discussion We eat more bacteria through daily consumption of fermented dairy products then through our consumption of functional food supplements. This offers a tremendous level to modulate the digestive tract through the intake of desired bacteria. This work reveals the probiotic potential of a mixture of lactic and propionic selected starters, in the context of fermented dairy products. A “two-in-one” ability is revealed for bacteria able both to produce a fermented dairy product and to modulate inflammation. Such an innovation opens new avenues for the reverse engineering development of anti-inflammatory fermented foods designed for target populations with IBD, and has provided evidences leading to an ongoing pilot clinical study in ulcerative colitis patients.

Maison de la Science en Bretagne Située sur le campus de Beaulieu de l'Université de Rennes 1, la Maison pour la science en Bretagne a ouvert ses portes en septembre 2014. Initiée par la Fondation "La main à la pâte" et par l’Académie des sciences, cette Maison est le fruit d’une collaboration exemplaire entre les universités, les grandes écoles bretonnes (dont AGROCAMPUS OUEST) et le rectorat d’académie. Elle propose à l’ensemble des professeurs des écoles et des collèges de l’académie de Rennes de participer à des actions de développement professionnel dans les domaines scientifiques. La 4iéme action de développement personnel, à destination des enseignants du collège, a eu lieu les 20 et 21 février avec l’intervention de plusieurs enseignants-chercheurs du dépt Productions animales, agroalimentaire, nutrition (PSAN). Romain Jeantet, Amélie Deglaire, Valérie Lechevalier, Françoise Nau et Catherine Guérin ont animé le module : « Les pieds dans le plat : transformer et conserver les aliments ». Infos : www.maisons-pour-la-science.orgContact : romain.jeantet@agrocampus-ouest.fr; Les pieds dans le plat : Les aliments, des produits vivants. 4ième action de développement personnel, à destination des enseignants du collège: module : « Les pieds dans le plat : transformer et conserver les aliments ».

Objectif : Identifier des bactéries qui possèdent à la fois des propriétés techno-fonctionnelles (levain) et des propriétés bio-fonctionnelles (probiotiques) pour orienter les fermentations vers des aliments fermentés probiotiques répondant aux besoins de populations cibles. Contexte . Les bactéries en transit dans notre tractus digestif ont un impact sur des facteurs clés de notre santé : immunité, inflammation, digestion, motilité, sensibilité et perméabilité de l’intestin. . Certains microorganismes sélectionnés probiotiques exercent un effet bénéfique sur l’un de ces paramètres clés, lorsqu’il est perturbé, mais n’ont pas de potentiel techno-fonctionnel reconnu. . Nous consommons beaucoup de bactéries, dans nos aliments fermentés, qui sont sélectionnées pour leurs propriétés techno-fonctionnelles, sans que leur potentiel bio-fonctionnel soit connu. Résultats publiés : . Le laboratoire INRA STLO a mis en évidence des propriétés bio-fonctionnelles, souches-dépendantes, chez la bactérie Propionibacterium freudenreichii utilisée comme levain d’affinage fromager. . Le laboratoire INRA MICALIS a fait de même chez les bactéries Lactobacillus delbrueckii et Streptococcus thermophilus utilisées comme levain des yaourts et de certains fromages. . STLO a identifié les molécules responsables de l’effet anti-inflammatoire de P. freudenreichii, a montré leur production au sein du fromage. . La combinaison de souches sélectionnées de P. freudenreichii et de L. delbrueckii a permis à ces deux équipes de mettre au point un fromage efficace in vivo à prévenir la colite. Perspectives de valorisation pour les entreprises d’une part, et de projets de recherche, d’autre part 9 lignes maximum . L’indentification de souches « 2-en-1 » au sein des espèces bactériennes utilisées en fermentation ouvre la voie à la mise au point d’aliments fermentés fonctionnels. . Bactéries propioniques et lactiques sélectionnées permettent d’envisager une large gamme d’aliments fonctionnels. . Un premier fromage fonctionnel immunomodulateur est en essai clinique dans le cadre d’un projet régional précompétitif . L’indentification des mécanismes immunomodulateurs impliqués offre des perspectives de développement de molécules actives

Introduction et but de l’étude: Les maladies inflammatoires chronique de l’intestin (MICI) sont reliées à divers facteurs, incluant le fond génétique, le système immunitaire, l’alimentation et d’autres facteurs environnementaux. Le microbiote intestinal est impliqué dans les MICI. La consommation de bactéries probiotiques sélectionnées peut induire ou prolonger des rémissions dans le cas de MICI telles que la RCH (rectocolite hémorragique). L’effet des bactéries consommées massivement dans les aliments fermentés est encore peu pris en compte. L’actinobactérie Propionibacterium freudenreichii est couramment consommée dans les fromages à pâte pressée cuite, ainsi que dans des compléments alimentaires probiotiques. Un grand nombre de souches sont disponibles pour cette espèce. Le but de cette étude était de 1) rechercher l’aptitude de certaines souches à induire la cytokine modulatrice IL-10, au niveau de cellules immunitaires humaines (PBMC), 2) développer un fromage expérimental « monosouche » avec la souche la plus immunomodulatrice de P. freudenreichii et 3) de tester l’impact de la consommation de ce fromage dans le contexte de la colite induite chez la souris. Matériel et méthodes: Les propionibactéries ont été cultivées sur ultrafiltrat de lait de vache supplémenté en peptone de caséine puis conservées à -20°C dans du PBS glycérolé (1 milliard de bactéries par mL). La colite aigue a été induite par administration intra-rectale de TNBS (100 mg/kg de poids corporel) et les animaux euthanasiés après 3 jours d’induction. L’inflammation a été quantifiée par mesure des score macroscopique Wallace et microscopique Ameho. Les résultats sont exprimés comme des moyennes ± SEM. Résultats et Analyse statistique : La consommation de ce fromage a protégé les souris de la colite aigue induite. L’induction de marqueurs locaux et systémiques de l’inflammation était réduite par la consommation du fromage. IL-6 : 366,17 ± 134 versus 1726,7 ± 548 pour le placebo (p ˂ 0,05). SAA : 29 812 ± 2 909 versus 9 535 ± 2 909 pour le placebo (p ˂ 0,05). La consommation de fromage a également conduit à une forte diminution de l’expression colique des gènes Il6, Cox2 et Hmox, des scores cliniques et anatomopathologiques. En revanche, cette consommation a restauré l’expression de Pparg et de Zo1. Globalement, ces résultats démontrent un effet protecteur du fromage fermenté par P. freudenreichii, et pas du fromage placébo stérile, vis-à-vis de l’induction de la colite aigüe. Conclusion: Cette étude confirme le potentiel probiotique précédemment décrit pour la bactérie alimentaire P. freudenreichii. Elle propose un nouveau produit laitier fermenté, et ouvre de nouvelles perspectives, pour des études pré-cliniques et cliniques ultérieures, visant la prévention et/ou l’aide au traitement de maladies inflammatoires.

Propionibacterium freudenreichii is an emergent probiotic, presenting several beneficial effects including anti-inflammatory properties, mediated by surface layer proteins (SLPs) belonged to the S-layer lattice, in particularly the protein SlpB. We hypothesize cheese matrix may be the best delivery vehicle for P. freudenreichii’s anti-inflammatory potential, by enhancing propionibacteria survival to digestives stresses, and by allowing undamaged SLPs to reach the digestive tract. Firstly, we compared the immunomodulatory effects of P. freudenreichii and intact SLPs, to SLPs digested by trypsin, i.e SLPs-peptides on HT29-cells. In contrast to P. freudenreichii and SLPs, SLPs peptides don’t reduce pro-inflammatory cytokines expression during cells co-stimulation with lipopolysaccharide. This result confirmed the importance to protect SLPs from proteolysis to permit them to trigger gut immune system. Secondly, we evaluated propionibacteria resistance and slpB proteolysis during in vitro static digestion, in different delivery vehicles increasingly concentrated in dairy proteins: milk ultrafiltrate, milk and cheese. The experiment clearly showed the protective effect of the Slp proteins by the cheese matrix and better bacterial viability. Then, we carried out in vitro a dynamic digestion using Didgi® system. We selected two matrices only: the milk ultrafiltrate and the cheese. We decided to apply fixed digestion parameters for both matrices: the digestive parameters of cheese. The results show a protective effect of the cheese matrix on the viability of the propionic bacteria and on SLPs against digestive proteolysis. Taken together, those results show that cheese is an adequate delivery vehicle for P. freudenreichii immunomodulatory proteins.

IBD constitute a growing public health concern in western countries. Inflammation is a key parameter involved in many non-communicable chronic diseases. Bacteria with anti-inflammatory properties are lacking in dysbiosis accompanying IBD. Selected strains of probiotic bacteria with anti-inflammatory properties accordingly alleviate symptoms and enhance treatment of ulcerative colitis in clinical trials. Such properties are also found in selected strains of dairy starters, including Propionibacterium freudenreichii and Lactobacillus delbrueckii, which are widely ingested. We investigated the possibility to develop a fermented dairy product, combining both starter and probiotic abilities of both lactic acid and propionic acid bacteria, designed to extend remissions in IBD patients.Methods & ResultsWe developed a two-strain P. freudenreichii and L. delbrueckii-fermented experimental pressed cheese using strains previously selected for their anti-inflammatory properties. This cheese was made in fully mastered conditions and contained only the two selected strains. It was consumed daily by mice during five days before induction of acute colitis by trinitrobenzenesulfonic acid (TNBS). Outcomes of colitis induction were then monitored in mice consuming this cheese or a placebo dairy matrix.For the first time, consumption of a designer P. freudenreichii and Lactobacillus delbrueckii pressed cheese was shown to protect mice against experimental colitis, alleviating severity of symptoms, modulating local and systemic inflammation, as well as colonic oxidative stress and epithelial cell damages. As a control, the corresponding sterile dairy matrix failed to afford such protection.ConclusionWe eat more bacteria through daily consumption of fermented dairy products then through functional food supplements. This offers a tremendous level to modulate the digestive tract through the intake of desired bacteria. This work reveals the probiotic potential of a mixture of lactic and propionic selected starters. A “two-in-one” ability is revealed for bacteria able both to produce a fermented dairy product and to modulate inflammation. Such an innovation opens new avenues for the reverse engineering development of anti-inflammatory fermented foods designed for target populations with IBD, and has provided evidences leading to an ongoing pilot clinical study in ulcerative colitis patients.This work was financed by the French National Agency for Research.

International audience

In this work, a simplified process from growth to spray drying of two probiotic strains, Lactobacilllus casei BL23 and Propionibacterium freudenreichii ITG P20, was proposed by utilizing concentrated sweet whey for growth and for achieving one-step drying of bacterial culture with higher dry matter of feed. Interestingly, after increasing the total solids of sweet whey from the original level of 5% to 20 - 30% (w/w), the two probiotic strains had higher final biomass production, instead of being inhibited by the high osmolality. The survival of the probiotics after spray drying was simultaneously improved, as well as during 6 months storage at 4 ºC. It was shown that this protective effect was due to enhanced multi-stress tolerance acquisition, overexpression of key stress proteins, and accumulation of intracellular storage molecules and compatible solutes upon growth in hyperosmotic medium.

Propionibacterium freudenreichii is a beneficial Actinobacterium, (GRAS & QPS status). It is exploited in the food industry for vitamins production and in Swiss type cheeses manufacturing, such as Emmental (1). Dairy propionibacteria have several probiotic features, including strain-dependent anti-inflammatory properties (Interleukine 10 induction by immune cells) (2). Previous studies showed surface protein (S- layer proteins) are involved in these properties (2), particularly the protein SlpB (Data no published).A monoxenic cheese, fermented by P.freudenreichii only, was developed. Consumption of this cheese reduced severity of chemically induced colitis in mice model (3). This shows the probiotic potential of P.freudenreichii for helping of Inflammatory Bowel Diseases (IBD) treatment. We assume cheese may be the best delivery vehicle of anti-inflammatory potential of P.freudenreichii to digestive tract. Indeed, we presume cheese enhances propionibacteria resistance to stress conditions during digestion. The presence of caseins matrix may exert a protective effect, allowing undamaged bacteria and surface proteins to reach the digestive tract.The experimental strategy chosen was to evaluate propionibacteria resistance and slpB protein proteolysis during in vitro digestion, in different delivery vehicles increasingly concentrated in dairy proteins: culture on milk ultrafiltrate (UF), culture on milk and a monoxenic cheese. P.freudenreichii viability and S-layer proteins susceptibility to proteolysis was followed in the different matrix during in vitro digestion. Two anti-inflammatory strains were used for this experiment: CIRM-BIA 129 and CIRM-BIA 118 (4).This will be correlated with in vivo experiments in the perspective to promote dairy products fermented by propionibacteria as probiotics for target populations.

National audience; Notre alimentation comporte environ 30 % d’aliments fermentés qui incluent fromages, yaourts, autres laits fermentés, saucisson et produits végétaux fermentés. Leur élaboration, autrefois traditionnelle et empirique, repose aujourd’hui sur l’utilisation pragmatique de bactéries bénéfiques, véritables ouvrières microscopique de la production de ces aliments. Ces bactéries sont intentionnellement introduites dans les aliments, de façon à maîtriser les fermentations alimentaires, et ceci pour deux raisons principales. Premièrement, les matières premières comme le lait sont aujourd’hui de plus en plus pauvres en bactéries, ce qui nécessite un ensemencement important pour démarrer les fermentations (on parle d’ailleurs de « starters », levain en français, au sujet de ces bactéries bénéfiques). Deuxièmement, cet ensemencement permet de contrôler la qualité du produit fermenté, au plan hédonique comme au plan des bénéfices pour la santé. En effet, nous disposons d’un nombre croissant d’évidence d’un rôle bénéfique de certaines espèces bactériennes pour la santé, dénommées alors bactéries « probiotiques ». Des scientifiques de l’UMR STLO ont récemment montré que certaines souches de bactéries fromagères présentaient des propriétés exceptionnellement prometteuses à la fois en tant que « starter » et en tant que « probiotique », ouvrant ainsi de nouvelles perspectives en termes de produits laitiers fonctionnels fermentés [1 brevet, 2]. Disposer à tout moment de bactéries bénéfiques caractérisées Les professionnels de l’aliment fermenté doivent disposer de bactéries bénéfiques faciles à stocker et mettre en œuvre dans leurs produits. Celles-ci sont majoritairement produites et conservées sous la forme de stocks déshydratés, qui sont ensuite réhydratés dans le produit pour démarrer la fermentation. Ces poudres sont relativement faciles à stocker et à mettre en œuvre. Leur production, en revanche, pose des problèmes en termes de développement durable. A l’échelle industrielle, les bactéries sont cultivées sur un milieu de culture, puis séparées de ce milieu épuisé, lavées, récoltées et remises en suspension dans un milieu de séchage. Ces suspensions sont dans la majorité des cas ensuite congelées avant lyophilisation (séchage sous vide, au froid). Ce procédé génère des milieux de culture épuisés qui doivent être retraités. Il consomme par ailleurs une quantité importante d’énergie pour l’élimination de l’eau par lyophilisation. Une alternative séduisante à ce procédé est le séchage par pulvérisation (air chaud), largement utilisé pour la production de poudres laitières au niveau industriel. La limite majeure de cette méthode de séchage appliquée aux cultures de bactéries bénéfiques est la grande fragilité de celles-ci vis-à-vis de la chaleur. Ainsi, peu de bactéries bénéfiques survivent au séchage par atomisation. Le séchage « 2-en-1 », une innovation majeure Nous avons mis au point un procédé « 2-en-1 » de culture et séchage sur lactosérum de fromagerie hyperconcentré. L’idée de départ est simple : puisqu’il est difficile de retirer l’eau après la culture des bactéries, essayons de cultiver avec moins d’eau dans la culture. Utilisons pour cela un coproduit de l’industrie laitière abondant : le lactosérum. Nous avons donc réalisé des cultures de bactéries bénéfiques sur du lactosérum 4 fois concentré. Les bactéries s’y développent, et elles acquièrent en plus une résistance exceptionnelle à la chaleur, par un mécanisme dit de « réponse adaptative » induit par ce nouveau milieu de culture [3]. Elles résistent donc parfaitement au séchage par pulvérisation grâce aux mécanismes d’adaptation [4], et présentent une survie accrue au cours du stockage. Les cultures sur lactosérum hyperconcentré sont directement séchées par pulvérisation sans étape de récolte ni d’élimination du milieu, puisque celui-ci est de qualité alimentaire, ce qui simplifie l’application du procédé et limite les risques de contamination. Ce séchage, sur un produit à teneur réduite en eau, se fait à des températures plus basses, en consommant moins d’énergie. Cette nouvelle méthode de production et de conservation de bactéries bénéfiques [5. brevet] permet de cultiver et de sécher « 2-en-1 » différentes bactéries dans une formulation laitière prête à l’emploi. Cette innovation offre de nouvelles perspectives pour la production de bactéries probiotiques à bas coût et pour leur usage étendu en nutrition humaine ou animale.

IntroductionProbiotic efficacy relies on administration of live and active probiotic strains in adequate dose. Growth yield and stress tolerance during probiotic production and delivery thus constitute a key bottleneck. Probiotics are widely produced, stored and used under a dried form, mainly by freeze-drying. Drying process generally comprises culture, harvesting, washing and drying steps in which preservation of viability remains a quest for the Holy Grail.MethodsThe aqueous phase of fermented dairy products was shown to enhance stress tolerance in both lactic and propionic acid bacteria. We used sweet whey, a dairy industry byproduct, as a two-in-one medium to sustain both growth of probiotics, and then directly spray-drying without harvesting and washing steps. Moreover, hyperconcentrated sweet whey was developed to achieve one-step drying with higher level of dry matter.ResultsBoth lactic and propionic acid bacteria were adapted to growth within sweet whey and resulting cultures were directly spray-dried with various survival rates, depending on dairy components concentration. Interestingly, growth of probiotics in hyperconcentrated sweet whey led to enhanced stress tolerance, overexpression of key stress proteins, accumulation of intracellular storage molecules and compatible solutes, consequently resulting in yet unknown survival upon heat, acid and bile challenges, as well as spray-drying and storage.DiscussionSpray- being far more cost-effective than freeze-drying, this innovation opens new avenues for sustainable development of probiotic products with enhanced delivery efficiency. This patent-protected new process indeed uses a dairy industry byproduct, requires limited amounts of energy, affords high bacterial viability and protects probiotics from injury undergone within the digestive tract.

International audience; Scope: TNF-Related Apoptosis-Inducing Ligand (TRAIL) induces apoptosis via the extrinsic death pathway in human colon cancer cells. Short Chain Fatty Acids (SCFA) by contrast induce apoptosis of cancer cells via the intrinsic death pathway. We have previously shown that food-grade dairy propionibacteria induce intrinsic apoptosis of colon cancer cells, via SCFA metabolites (propionate and acetate) acting on mitochondria. We investigate here the possible synergistic pro-apoptotic effect between Propionibacterium freudenreichii and TRAIL. Methods and results: Whole transcriptomic analysis demonstrated that propionibacterial supernatant or propionibacterial SCFA, in combination with TRAIL, increased pro-apoptotic gene expression (TRAIL-R2/DR5) and decreased anti-apoptotic gene expression (FLIPL, XIAP) in HT29 human colon cancer cells. The revealed synergistic pro-apoptotic effect, depending on both death receptors (TRAIL-R1/DR4, TRAIL-R2/DR5) and caspases (caspase-8, -9 and -3) activation, was lethal on cancer cells but not on normal human intestinal epithelial cells (HIEC), and was inhibited by Bcl-2 expression. Finally, milk fermented by P. freudenreichii induced HT29 cells apoptosis and enhanced TRAIL cytotoxic activity, as did P. freudenreichii culture supernatants or its SCFA metabolites. Conclusion: The revealed synergy opens new applications for food-grade P. freudenreichii-containing products as new adjuvants to potentiate TRAIL-based cancer therapy in colorectal cancer.

Cheeses and other fermented dairy products constitute a tremendous source of live and active bacteria in our diet. Depending on the product, on the strain and on the health status of individuals, this major bacterial intake can have beneficial effects, or not! Recognized molecular, cellular and animal models have been developed to detect and study probiotic bacterial strains. These tools may also reveal unexpected probiotic potential in bacterial strains within the tremendous biodiversity present in traditional fermented products. In our team, we focused on dairy propionibacteria, taking advantage of a unique biological resource center. Propionibacterium freudenreichii is a beneficial bacterium used in the food industry as a vitamin producer, as a bio-preservative and as a cheese ripening starter. We hypothesized that strains considered for techno-functional reasons (aroma, texture), may also play a beneficial role as probiotics.Food-grade dairy propionibacteria are nutraceutical producers. They release short chain fatty acids (SCFAs), folic acid and cobalamin, which play a role in intestinal physiology. SCFAs induce apoptosis via the mitochondrial death pathway. We investigate the potential of dairy propionibacteria-fermented products to synergize with drugs used in gastric and colorectal cancer.Some strains are known to adhere to intestinal epithelial cells and mucus and to modulate important functions of the gut mucosa, including cell proliferation and immune response. Selected strains show promising immunomodulatory properties with an anti-inflammatory protective evidenced effect in vitro and in vivo. We thus developed experimental monoxenic fermented dairy products, exclusively fermented by an anti-inflammatory selected strain of P. freudenreichii. Key surface proteins, involved in its immunomodulatory effects, are expressed within these products. Their consumption exerted an anti-inflammatory effect in vivo.These results open new perspectives in the field of prevention and/or treatment of intestinal cancer (CRC) and inflammatory diseases (IBD). The synergy with pro-apoptotic chemotherapy molecules suggests that such a fermented product, or the Propionibacterium alone, may be proposed as a food supplement to enhance the effects of anticancer treatments. The preventive effect in the context of induced colitis suggests that it could potentialize IBD treatment.This work reveals an unexpected probiotic potential in industrial dairy propionibacteria starters. It opens exciting perspectives in a context of growing occurrence of IBD, multifactor diseases related to diet, and provides a new functional fermented product for preclinical and clinical studies aimed at prevention or treatment of IBD.

Propionibacterium freudenreichii is a beneficial bacterium used as vitamin producer, bio-preservative, cheese ripening starter and probiotic. It adheres to intestinal epithelial cells and mucus and modulates the immune response. Interaction with the host is strain-dependent and relies on key surface proteins, still poorly investigated. We identified surface-exposed proteins in a strain previously selected for its probiotic properties. The role of these proteins in immunomodulatory properties was evidenced. Cheese being a major source of bacteria, we developed an experimental pressed cheese, exclusively fermented by a single strain of P. freudenreichii. Key surface proteins involved in the observed immunomodulatory effects were expressed within the cheese matrix. Consumption of this single-strain cheese protected mice from acute colitis induced by TNBS. P. freudenreichii expressed the key genes of stress tolerance response during growth in the aqueous phase of Emmental cheese, in agreement with enhanced stress tolerance, compared to laboratory culture medium.This work confirms the probiotic potential of P. freudenreichii, it provides a new functional fermented product for preclinical and clinical studies aimed at prevention or treatment of IBD. It constitutes a basis for further studies aimed at the elucidation of mechanisms responsible for its probiotic effects, in a post-genomic context.

Dossier de Sciences Ouest : Les super-pouvoirs des microbes

La microbiologie du lait et de sa transformation

Cinetica de acidificacao de [i]lactobacillus plantarum[/i] submetido a secagem por atomizacao e liofilizacao. 30. Congresso Nacional de Laticínios

Cheeses and other fermented dairy products constitute a tremendous source of live and active bacteria in our diet. Depending on the product, on the strain and on the health status of individuals, this major bacterial intake can have beneficial effects, or not! Recognized molecular, cellular and animal models have been developed to detect and study probiotic bacterial strains. These tools may also reveal unexpected probiotic potential in bacterial strains within the tremendous biodiversity present in traditional fermented products. In our team, we focused on dairy propionibacteria, taking advantage of a unique biological resource center. We hypothesized that strains considered for techno-functional reasons (aroma, texture), may also play a beneficial role in the context of Inflammatory Bowel Diseases (IBD).Propionibacterium freudenreichii is a beneficial bacterium used in the food industry as a vitamin producer, as a bio-preservative and as a cheese ripening starter. Some strains are known to adhere to intestinal epithelial cells and mucus and to modulate important functions of the gut mucosa, including cell proliferation and immune response. Selected strains show promising immunomodulatory properties with an anti-inflammatory protective evidenced effect in vitro and in vivo. Adhesion of probiotics and cross-talk with the host rely on the presence of key surface proteins, still poorly identified. Identification of the determinants of adhesion and of immunomodulation by P. freudenreichii remains a bottleneck in the elucidation of its probiotic properties.During 3 years, a national research project funded by ANR (Agence Nationale de la Recherche) investigated statistical links between immunomodulatory properties of 23 P. freudenreichii strains and their cellular proteins using comparative genomics, transcriptomics and proteomics. In particular, three complementary proteomic methods were used to identify key surface-exposed proteins involved in probiotic effects. We then developed experimental monoxenic fermented dairy products, exclusively fermented by an anti-inflammatory selected strain of P. freudenreichii. Key surface proteins, involved in its immunomodulatory effects, were expressed within these products. Their consumption exerted an anti-inflammatory effect in vivo.This work reveals an unexpected probiotic potential in industrial dairy propionibacteria starters. It opens exciting perspectives in a context of growing occurrence of IBD, multifactor diseases related to diet, and provides a new functional fermented product for preclinical and clinical studies aimed at prevention or treatment of IBD.

Trois technologies innovantes pour le séchage des probiotiquesAlors que la méthode la plus utilisée reste la lyophilisation, l'enjeu du séchage des probiotiques est double : préserver les bactéries et réduire les coûts opératoires, notamment liés aux consommations d'énergie.La lyophilisation, qui agit par combinaison du froid et du vide, est la méthode de séchage la plus répandue à grande échelle pour conserver des bactéries. Mais elle est onéreuse et gourmande en énergie. D’autres alternatives, comme l’atomisation et la fluidisation, peuvent être mises en œuvre mais elles font appel à la chaleur, avec pour conséquences des taux de survie inférieurs et des pertes de fonctionnalité des souches. Se pose dès lors la question d'un séchage respectueux des probiotiques, avec des coûts opératoires modérés.Une baisse des coûts opératoiresUn premier élément de réponse est apporté par le Nizo Food Research qui développe un nouveau procédé de séchage, pouvant être réalisé sur des équipements existants. Le centre de recherche annonce des taux de survie de probiotiques atteignant 75 %, alors que dans le cas du séchage par atomisation il peine à atteindre 20 %. Cette augmentation significative entraîne une baisse globale des coûts opératoires pour les applications mettant en œuvre ces bactéries. Une demande de brevet a été déposée pour ce nouveau process, qui peut être intégré dans les schémas de fabrication de tout type de produits secs. La technologie est conçue de manière à pouvoir sécher aussi bien par batch de 0,5 kg que de plusieurs tonnes de produits.Jusqu'à 100 % de survieUne autre solution est à découvrir du côté du laboratoire STLO (Science et Technologie du Lait et de l’œuf) de l'Inra de Rennes. Les scientifiques y ont imaginé un procédé simplifié et peu coûteux de séchage par atomisation, ayant une efficacité proche de celle d’un séchage par lyophilisation. L’atomisation classique nécessite une première étape de culture du micro-organisme sur milieu optimisé, suivie d’un rinçage et d’une remise en suspension dans un nouveau milieu avant séchage à haute température. Le nouveau procédé comprend uniquement un séchage effectué directement sur un milieu de culture, développé spécifiquement et composé de lactosérum. Testé sur deux souches probiotiques, l’une fragile et l’autre robuste, la méthode a démontré une efficacité comparable à celle d’une lyophilisation, avec des taux de survie respectifs de l’ordre de 40-50% et de 100%. La stabilité des micro-organismes dans le temps a été vérifiée à quatre et six mois, avec des résultats comparables à ceux d’une lyophilisation, pour des coûts de production nettement inférieurs, avec notamment une consommation d’énergie bien plus basse.Un pilote pour une technologie innovanteLa technologie EPT (extrusion porosification) brevetée par Clextral peut elle aussi constituer une solution pour le séchage des probiotiques. Le procédé est divisé en quatre opérations : une concentration poussée, l'extrusion-porosification (extrudeurs bi-vis et injection de gaz) du produit visqueux obtenu, le séchage par atomisation et un séchage final sur lit fluidisé. Concernant les probiotiques, « nous avons réalisé des essais avec succès dans la station en Australie », se félicite Alain Brisset, responsable des marchés clefs de Clextral. La filiale de Legris Industrie conduit progressivement l'industrialisation de ce procédé, avec pour objectif un lancement en 2018. Début 2016, un équipement pilote devrait entrer en fonctionnement à Cérences dans la Manche sur le site de Lesaffre Ingrédients Services, l’un des co-investisseurs partenaires de Clextral, avec Diana Pet Food et Triballat-Noyal. « L’équipement sera ouvert aux partenaires extérieurs pour des essais courant 2016 selon un protocole défini », précise Alain Brisset.

International audience; BackgroundPropionibacterium freudenreichii is a food grade bacterium consumed both in cheeses and in probiotic preparations. Its promising probiotic potential, relying largely on the active release of beneficial metabolites within the gut as well as the expression of key surface proteins involved in immunomodulation, deserves to be explored more deeply. Adaptation to the colon environment is requisite for the active release of propionibacterial beneficial metabolites and constitutes a bottleneck for metabolic activity in vivo. Mechanisms allowing P. freudenreichii to adapt to digestive stresses have been only studied in vitro so far. Our aim was therefore to study P. freudenreichii metabolic adaptation to intra-colonic conditions in situ.ResultsWe maintained a pure culture of the type strain P. freudenreichii CIRM BIA 1, contained in a dialysis bag, within the colon of vigilant piglets during 24 hours. A transcriptomic analysis compared gene expression to identify the metabolic pathways induced by this environment, versus control cultures maintained in spent culture medium.We observed drastic changes in the catabolism of sugars and amino-acids. Glycolysis, the Wood-Werkman cycle and the oxidative phosphorylation pathways were down-regulated but induction of specific carbohydrate catabolisms and alternative pathways were induced to produce NADH, NADPH, ATP and precursors (utilizing of propanediol, gluconate, lactate, purine and pyrimidine and amino-acids). Genes involved in stress response were down-regulated and genes specifically expressed during cell division were induced, suggesting that P. freudenreichii adapted its metabolism to the conditions encountered in the colon.ConclusionsThis study constitutes the first molecular demonstration of P. freudenreichii activity and physiological adaptation in vivo within the colon. Our data are likely specific to our pig microbiota composition but opens an avenue towards understanding probiotic action within the gut in further studies comparing bacterial adaptation to different microbiota.

Propionibacterium freudenreichii is a food grade bacterium consumed both in cheeses and in probiotic preparations. Its promising immunomodulatory potential largely relies on the presence of specific and strain-dependent surface compounds. The CIRM BIA 129 strain was selected for immunomodulatory properties, its surfaceome deciphered using an integrative approach. Surface Layer Associated Proteins (SLAPs) are involved in the anti-inflammatory properties

Propionibacterium freudenreichii is the main Propionibacterium consumed both in traditional cheeses and in innovative probiotic product. A portion of 10 grams of Emmental cheese provides around 10 10 live P. freudenreichii , a major bacterial intake in France and other industrialized countries. Surprisingly, little is known about its effect on human health, compared to lactobacilli or bifidobacteria. However, recent works indicate promising beneficial effects including modulation of intestinal microbiota, metabolic activities and inflammation. In this context, the molecular mechanisms responsible for the immunomodulatory properties of P.freudenreichii , and of fermented dairy product containing it, were investigated. In that aim, an integrative approach was undertaken, in a research program of the French National Agency for Research (ANR). It consisted of the sequencing and annotation of the genomes of 20 strains, followed by comparative genomics, in the design of a pangenomic chip, followed by comparative transcriptomic analysis , in a comparative surface proteomic analysis, and in comparison of the immunomodulatory properties, ex vivo and in vivo , using model cheeses. This investigation reveals, for the first time, the molecular mechanism responsible for modulation of the immune system and of inflammation by P.freudenreichii . These results are in accordance with clinical results obtained by others with the same bacterium

MicrobiologieUn projet de recherche explore le potentiel anti-inflammatoire de certaines bactéries présentes dans l’emmental.Les Français sont de gros mangeurs d’emmental. Ils en consomment environ 20 g par personne et par jour en moyenne. Outre le calcium, nous ingérons grâce à cet emmental des milliards de milliards de bactéries. Depuis 2011, le projet Surfing(1), coordonné par Gwenaël Jan, de l’Inra de Rennes, s’intéresse aux propriétés de certaines d’entre elles : les bactéries propioniques laitières. « Ce sont des levains lactiques. Elles sont bien connues et utilisées par l’industrie agroalimentaire pour leurs aptitudes à apporter un arôme, une texture ou les “yeux” du fromage. Et elles sont ultrarésistantes ! »Une sélection prometteuseCes bactéries peuvent-elles, en plus, avoir des qualités pour notre santé ? « Pour le projet, nous avons choisi Propionibacterium freudenreichii, car nous avions déjà décrypté le génome de vingt souches. » En parallèle, une équipe de l’Inra de Jouy-en-Josas(2) s’est attaquée à la même problématique avec des lactobacilles présents dans le yaourt. « Nous nous sommes focalisés sur la modulation de maladies inflammatoires de l’intestin, qui augmentent en Europe. » Des études précédentes avaient déjà montré que d’autres bactéries alimentaires pouvaient avoir un effet bénéfique dans le traitement de l’une de ces pathologies, la rectocolite hémorragique.« C’est un projet exploratoire, préclinique, précise Gwenaël Jan. Nous avons mené des expérimentations in vitro puis sur des modèles animaux. » Les chercheurs ont d’abord comparé les génomes de vingt souches de bactéries, qui ont ensuite été envoyées à l’Institut Pasteur de Lille, où leur capacité à agir sur la réponse immunitaire, donc sur l’inflammation, ont été testées. Certaines se sont démarquées dès cette étape. « Nous avons confirmé ces différences par d’autres tests in vitro, puis nous avons sélectionné deux souches : la plus et la moins prometteuse, pour les tester sur des souris. » Les résultats ont été à la hauteur des attentes : les bactéries au plus fort potentiel in vitro ont révélé de véritables effets anti-inflammatoires sur les petits rongeurs malades. « Cela ne signifie pas que l’on peut soigner avec ces bactéries, mais qu’elles peuvent avoir un rôle positif dans le traitement. »Du fromage pour les sourisEn parallèle, avec un partenaire industriel(3) et un centre technique(4), l’équipe a fait réaliser des fromages contenant chacun une des deux bactéries testées. « C’était un défi technique car, normalement, il faut plusieurs bactéries différentes pour faire un fromage ! » Les produits obtenus ne ressemblent pas vraiment au beau morceau d’emmental du commerce, mais peu importe. Les chercheurs ont été soulagés de voir que les bactéries n’avaient pas été altérées par cette transformation, par les variations de températures notamment. Quelques échantillons sont partis à l’Institut Pasteur de Lille, pour nourrir les souris malades. « Ces résultats, encourageants, ne sont pas encore publiés », précise le scientifique. Le projet Surfing se termine, mais dès 2015, l’équipe de l’Inra va pouvoir travailler avec des gastroentérologues du CHU de Rennes, dans le cadre d’un projet retenu par le Conseil régional de Bretagne(5), pour tester la souche la plus prometteuse dans une étude clinique.

This book underlines the importance of reciprocal interactions between probiotics and humans in terms of stress induction, epigenetic control of cellular responses, oxidative status, bio-active molecules biosynthesis, moonlighting proteins secretion, endogenous toxins neutralization, and several other biological functions. It explores how these responses can affect metabolism and metabolic-related disorders, gutbrain axis balance, mood, inflammatory, allergic and anti-infective reactions, cancer, and ageing. The book explores how probiotics create a dynamic and "fluid" network of signals able to control the balance between healthy and altered human status.

Propionibacterium freudenreichii is consumed in elevated amounts both as a cheese starter (1010 CFU/D/person in France) and as a probiotic bacterium, while its effect on health is poorly understood. We investigate its immunomodulatory properties, in a context of growing occurrence of inflammatory bowel diseases. Twenty strains were compared in this regard in vitro using human PBMCs (Peripheral Blood Mononuclear cells), revealing strain dependent cytokine stimulatory properties. They also afforded strain-dependent protection in vivo towards colitis. A fermented milk, exclusively fermented by P. freudenreichii, was developed and tested in a healthy piglet model. It promoted growth health of the piglets and delivered live and metabolically active propionibacteria to the gut. Its consumption reduced gut mucosa production of pro-inflammatory IL-8 and TNF-α. Among strains, a genomic, transcriptomic and proteomic approach revealed contrasted effects of propionibacterial surface compounds such as exopolysaccharides and proteins. Specific proteins are involved in immunomodulation, while capsular exopolysaccharides abolish it. The role of each key compound is presently investigated in an ANR project (Sarter SURFace against INflammation of the Gut) in a multidisciplinary approach involving 7 partners. Elucidation of molecular and cellular mechanisms, together with in vivo anti-inflammatory effects, will open new perspectives for the use of fermented dairy products containing P. freudenreichii addressing the needs of specific populations.

Staphylococcus aureus is an opportunistic pathogen in dairy ruminants where it is a major cause of mastitis and can be also found in healthy carriage. A better knowledge of the host-pathogen interactions is needed to tackle this serious animal health problem. This study aimed at identifying S. aureus proteins differentially expressed during nasal colonization versus mastitis. Serological proteome analysis (SERPA) was used to examine protein samples prepared from culture supernatants of S. aureus strains originally isolated from gangrenous mastitis and nasal carriage (O11) or subclinical mastitis (O46) and to compare patterns of immune-reactive proteins. These staphylococcal proteins were revealed by sera obtained from ewes suffering from S. aureus mastitis and by sera obtained from healthy nulliparous ewes (i.e. no lactation and no mastitis or other symptoms) that were nasally colonized by S. aureus. Altogether 49 staphylococcal immune-reactive proteins were identified in this study. Patterns of proteins revealed by sera from infected- or healthy carrier- animals were comparable and analysis singled out one immune-reactive protein, an N-acetylmuramyl-L-alanine amidase, which was recognized by each of the 6 sera from infected animals, when tested individually, and not by the sera of healthy carriers. This is the first study that compares the S. aureus seroproteome in colonization versus mastitis context in ruminants. These results open avenues for studies aiming at a better understanding of the balance between infection and commensal lifestyle in this opportunistic pathogen and at new prevention strategies.

Dairy propionibacteria, mainly Propionibacterium freudenreichii, are consumed in high amounts within cheeses. They are also known as probiotics able to modulate the gut microbiota and the corresponding metabolic activities. Their immunomodulatory properties, analyzed here on human PBMCs, displayed a remarkable variability, depending on the P. freudenreichii strain. Moreover, such modulating properties varied depending on the culture medium considered, i.e. laboratory culture medium versus fermented dairy product. Selected anti-inflammatory strains were further tested in 2 distinct mice experimental colitis models, revealing significant protection and confirming for these cheese starter bacteria (i) probiotic potential and (ii) predictive value of immune-based selection criteria. The role of surface component, including surface exopolysaccharide (EPS) and surface exposed proteins (SEPs), in this modulation, was investigated. We showed that presence of EPS abrogates immunomodulation while presence of key SEPs determines nature and intensity of this modulation. These key SEPs are being identified, as well as the mechanisms leading to their variability. These results open new perspectives for propionibacteria selection aiming at probiotic applications and new mechanistic explanation of their effects on the digestive tract.

Background and objectives.[br/] Dairy propionibacteria are isolated from various ecological niches, including soil, grass, silage, rumen, raw milk and dairy plants, showing great adaptability and robustness. Used as ripening starters in Swiss type cheeses, these food grade bacteria are described as nutraceutical producers and they release into the external medium short chain fatty acids (SCFA), folic acid, cobalamin and the bifidogenic 1,4- dihydroxy-2-naphthoic acid (DHNA). These compounds are known to play a pivotal role in the modulation of intestinal physiology through diet. Considering the pro-apoptotic potential of some of these metabolites, we investigated the potential of dairy products fermented by the main species, Propionibacterium freudenreichii, to prevent colon carcinogenesis. Methods.[br/] We developed a new fermented milk. Taking advantage of milk fractions, high and stable populations of P. freudenreichii were obtained in this product. It was tested in vitro on gastric HGT-1 and colic HT-29 cells with respect to the typical hallmarks of apoptosis. In vivo, the fermented milk was evaluated in piglets with respect to general health parameters and in human microbiota-associated rats, treated or not with dimethylhydrazine (DMH), with respect to intestinal proliferation and apoptosis. Results. Fermented milk induced cell death in both gastric and colon cancer cells. Cellular and molecular characterization of cells dying in response to SCFA treatment revealed cell cycle arrest, drop in intracellular ATP, depolarization of mitochondria, translocation of key apoptosis proteins, processing of caspases and fragmentation of the nucleus. Interestingly, the new fermented milk was shown to potentiate the cytotoxic effect of molecules used in cancer chemotherapy. In accordance, it modulated expression of key apoptotic proteins. In vivo, the fermented milk was evaluated in piglets. Daily oral gavage led to high colic P. freudenreichii populations, to modulation of the intestinal microbiota and modulation of intestinal cytokines. Promotion of piglets’ growth also revealed general probiotic effects of fermented milk. Considering that propionibacteria were metabolically active in the intestine, we further investigated their impact on colon carcinogenesis (induced by dimethylhydrazine, DMH) in human microbiota-associated rats. Consumption of selected strains of propionibacteria resulted in enhanced apoptotic depletion of DMH damaged epithelial cells, yet had no effect on neither proliferation nor apoptosis in healthy rats. Conclusions and perspectives.[br/] These results open new perspectives in the field of colon cancer cells prevention and/or treatment. The synergy with pro-apoptotic chemotherapy molecules suggests that such a fermented product may be proposed as a food supplement to enhance the effects of anticancer treatments.

Recent works have revealed highly strain-dependent immunomodulatory properties in Propionibacterium freudenreichii, a cheese starter bacterium (Foligné et al. 2010). The underlying mechanisms are unknown but preliminary attempts have shown that surface components are involved in these immunomodulatory effects. The most promising strains/components exert promising anti-inflammatory effects through induction of regulatory cytokines. The aim of this work is to identify key surface components of Propionibacterium freudenreichii responsible for the immunomodulatory properties. 12 strains of Propionibacterium freudenreichii were sorted according to their high or low regulatory properties, measured by induction of IL-10 cytokine in peripheral blood mononuclear cells stimulated by equal amounts of the different P. freudenreichii strains. These strains were sequenced by Illumina paired-end sequencing and de novo assembled using Velvet software. Genome sequences were automatically and manually annotated on the INRA-AGMIAL platform. Correlations are studied both (i) between quantitative traits (high or low induction of IL-10) and genotypic properties, namely presence/lack of in silico predicted proteins and (ii) between quantitative traits (high or low induction of IL-10) and in vitro data (surface exposed proteins). In both cases, we account for the phylogenetic inertia induced by the shared evolutionary history of the strains. For in vitro data, three methods (shedding using guanidium chloride, surface labeling using CyDye cyanine and shaving using trypsine combined with mass spectrometry) are used to identify P. freudenreichii surface proteins. Statistical analysis is used to highlight which of these proteins can potentially be involved in immunomodulation, comparing the proteins identified and IL-10 induction. Statistical analyses of both in vitro and in silico approaches based on genome sequencing reveal targets potentially involved in immunomodulation. Both strategies are complementary. Proteomic approach followed by statistical analysis allow the identification of surface exposed proteins associated with immunomodulation, whereas in silico approach point out the mechanisms explaining the presence/ absence of the candidates on bacterial surface. Genome sequences, either directly used (in silico approach) or used as database (in vitro approach) determine key genes involved in the studied phenotypes. Candidate genes identified in the present study will be further characterized and their role in immunomodulation confirmed by knock out or overexpression of selected genes.

Staphylococcus aureus is a major pathogen in ruminant mastitis. Staphylococcal mastitis in ovine hosts is remarkably variable in terms of acuteness and ranges from subclinical to gangrenous mastitis. S. aureus factors involved in such variations are still poorly documented. This study aimed at identifying the staphylococcal factors responsible for the acuteness of the infection. Two S. aureus strains, isolated from gangrenous (O11) or subclinical (O46) ewe mastitis, were selected for this work. Despite a close phylogenetic relationship, these strains were shown to reproducibly induce severe (O11) or mild (O46) symptoms in experimental ewe mastitis. Several omic approaches were combined to compare these two strains. Both strains were fully sequenced and their transcriptome and proteome were analyzed in culture conditions mimicking mastitis context. Results showed that dramatic differences between O11 and O46 rely on their ability to adapt to and to express their virulence in a mammary context rather than in their gene content. This study highlights differences in the expression of genes related to mobile genetic elements (especially prophages), the expression of genes involved in iron acquisition and metabolism, of transcriptional factors (SigmaB and SigmaS) and in exoprotein production. Serological Proteome Analysis (SERPA) showed that most of these exoproteins are indeed produced during mastitis. Analysis of 10 other S. aureus strains, focused on two of these exoproteins –SspB and a protein of unknown function- showed SspB is produced only in strains isolated from severe mastitis and the protein of unknown function in strains isolated from subclinical mastitis. The exact role of the genes identified here (exoproteins, mobile genetic elements, iron metabolism and acquisition) in the infection and in mastitis acuteness remains to be determined. Finally, we showed that O11 is transformable and can thus be subjected to mutagenesis. The genes identified here represent excellent candidates for targeted studies of the molecular basis of S. aureus pathogenesis in ruminant mastitis.

Recent works have revealed highly strain-dependent immunomodulatory properties in Propionibacterium freudenreichii, a cheese starter bacterium. The underlying mechanisms are unknown but preliminary attempts have shown that surface components are involved in these immunomodulatory effects. The most promising strains/components exert promising anti-inflammatory effects through induction of regulatory cytokines.The aim of this work is to identify key surface components of Propionibacterium freudenreichii responsible for the immunomodulatory properties. 12 strains of Propionibacterium freudenreichii were sorted according to their high or low regulatory properties, measured by induction of IL-10 cytokine in peripheral blood mononuclear cells stimulated by equal amounts of the different P. freudenreichii strains. These strains were sequenced by Illumina paired-end sequencing and de novo assembled using Velvet software. Genome sequences were automatically and manually annotated on the INRA-AGMIAL platform. Correlations are studied both (i) between quantitative traits (high or low induction of IL-10) and genotypic properties, namely presence/lack of proteins predicted in silico and (ii) between quantitative traits (high or low induction of IL-10) and in vitro data (surface exposed proteins). In both cases, we account for the phylogenetic inertia induced by the shared evolutionary history of the strains. For in vitro data, three methods (shedding using guanidium chloride, surface labeling using CyDye cyanine and shaving using trypsine combined with mass spectrometry) are used to identify P. freudenreichii surface proteins. Statistical analysis is used to highlight which of these proteins can potentially be involved in immunomodulation, comparing the proteins identified and IL-10 induction. Statistical analyses of both in vitro and in silico approaches based on genome sequencing reveal targets potentially involved in immunomodulation. Both strategies are complementary. Proteomic approach followed by statistical analysis allow the identification of surface exposed proteins associated with immunomodulation, whereas in silico approach point out the mechanisms explaining the presence/ absence of the candidates on bacterial surface.Genome sequences, either directly used (in silico approach) or used as database (in vitro approach) determine key genes involved in the studied phenotypes. Candidate genes identified in the present study will be further characterized and their role in immunomodulation confirmed by knock out or overexpression of selected genes.

Propionibacterium freudenreichii is known to play a key role in the formation of cheese flavor throughout Swiss-type cheese ripening and especially during cold storage of cheese. At every stage of cheese manufacture, P. freudenreichii has to face several stresses-generating conditions and especially a cold-induced stress when Swiss cheeses are transferred from a warm (24°C) ripening room to a cold (4°C) room. The aim of this study was to investigate the adaptation and survival of P. freudenreichii at cold temperature by means of the first global gene expression profile for this species. The temporal transcriptomic response of P. freudenreichii was analyzed during its growth phase at 30°C and then during further incubation at 4°C for 9 days, always preventing any exhaustion of the main carbon source (lactate). As the cells transitioned from the warm to the cold condition, most of the down-expressed genes were involved in cell division, protein turnover, translation, transcription and DNA replication and repair. During incubation at cold temperature, P. freudenreichii adopted multiple strategies for maintaining its viability. It activated a two-component quorum-sensing system (a two-component system sensor kinase and luxR) that can induce population-wide changes in gene expression. It used polyphosphate supplies as energy sources by activating genes coding for Nudix hydrolases and pyrophosphatases. It accumulated carbon supplies by up-regulating genes of lactate, alanine and serine conversion to pyruvate, of aspartate conversion to fumarate, of gluconeogenesis and of glycogen synthesis. Thus, even if its metabolic activity is slowed down at cold temperature, P. freudenreichii remains active, which could explain its ability to continue the production of aroma compounds in cheese during their ripening at low temperature. Understanding the metabolism of P. freudenreichii during cold storage could constitute a real asset for a better optimization of Swiss cheese ripening process thus decreasing the carbon footprint of Swiss-type cheese manufacture

Cette publication est également parue dans la revue "Journal of Animal Science", Vol.89, E-Suppl.1.; Staphylococcus aureus is a major cause of mastitis in ruminants. In ewe mastitis, symptoms range from subclinical to gangrenous mastitis. S. aureus factors or host-factors contributing to the different outcomes are not completely elucidated. In this study, experimental mastitis was induced on primiparous ewes using two S. aureus strains, isolated from gangrenous (strain O11) or subclinical (strain O46) mastitis. Strains induced drastically distinct clinical symptoms when tested in ewe and mice experimental mastitis. Notably, they reproduced mild (O46) or severe (O11) mastitis in ewes. Ewe sera were used to identify staphylococcal immunoreactive proteins commonly or differentially produced during infections of variable severity and to define core and accessory seroproteomes. Such SERological Proteome Analysis (SERPA) allowed the identification of 89 immunoreactive proteins, of which only 52 (58.4%) were previously identified as immunogenic proteins in other staphylococcal infections. Among the 89 proteins identified, 74 appear to constitute the core seroproteome. Among the 15 remaining proteins defining the accessory seroproteome, 12 were specific for strain O11, 3 were specific for O46. Distribution of one protein specific for each mastitis severity was investigated in ten other strains isolated from subclinical or clinical mastitis. We report here for the first time the identification of staphylococcal immunogenic proteins common or specific to S. aureus strains responsible for mild or severe mastitis. These findings open avenues in S. aureus mastitis studies as some of these proteins, expressed in vivo, are likely to account for the success of S. aureus as a pathogen of the ruminant mammary gland.

Nutrition-SantéSurfing évalue le potentiel anti-inflammatoire des produits laitiers fermentésmercredi 9 février 2011 Surfing - Inra/Agrocampus OuestGwénaël Jan, de l’UMR Inra/Agrocampus Ouest Science et technologie du lait et de l'œuf, coordonne le projet Surfing. Parmi les espèces bactériennes qu’il étudie, Propionibacterium freudenreichii est ici photographié en interaction avec une cellule de côlon humain sous microscope électronique à balayage. (© Inra)Le projet Surfing porté par l'unité mixte de recherche Inra/Agrocampus Ouest Science et technologie du lait et de l'œuf (UMR STLO) et par l'unité mixte de recherche Inra/AgroParis Tech Micalis (Microbiologie de l’alimentation au service de la santé humaine) vient d’être sélectionné par l’Agence nationale de la recherche (ANR).Il va étudier les propriétés anti-inflammatoires de deux bactéries communément utilisées dans la fermentation des fromages et des yaourts. L’objectif est de montrer que l’ingestion de produits laitiers contenant ces deux bactéries peut avoir un impact pour lutter contre les maladies inflammatoires chroniques intestinales qui touchent 200 000 personnes en France et dont la plus connue est la maladie de Crohn.La première étape va s’intéresser à l’identification des protéines responsables des propriétés anti-inflammatoires des souches bactériennes et à la validation de ces propriétés in vitro et in vivo. Dans un second temps, il faudra vérifier la présence de ces protéines dans les deux bactéries lors de leur production industrielle et lors de la fabrication des produits laitiers. Enfin, une étape de transfert de technologie permettra de mettre à disposition des industriels les outils développés pour évaluer le potentiel anti-inflammatoire des souches bactériennes.Sur trois ans, Surfing va mobiliser trois laboratoires Inra, un laboratoire de l’Institut Pasteur, l’institut technique Actilait, le Cniel et l’entreprise caennaise Laboratoires Standa. D’un coût total de 2,31 millions d’euros financés à hauteur de 560 000 euros par l’ANR, le projet est labellisé par les pôles de compétitivité Valorial et Nutrition-Santé-Longévité de Nord Pas de Calais.