The microbial resources generated by research in agronomy in the service of innovation

The microbial resources generated by research in agronomy in the service of innovation. European Culture Collections' Organisation:ECCO XXX

Influence de stress environnementaux sur le comportement et le protéome de Listeria monocytogenes (Application aux ateliers de production fromagère)

Listeria monocytogenes est une bactérie pathogène ubiquiste responsable de toxi-infections alimentaires chez l'homme et l'animal. Le contact des denrées alimentaires avec un équipement de production souillé représente une source potentielle de contamination dont les conséquences dépendent de l'état physiologique des bactéries incriminées. Dans les industries alimentaires, l'alternance des périodes de production et des opérations de nettoyage occasionne des stress thermiques et de carence nutritionnelle pour les bactéries de l'environnement, majoritairement présentes sous forme de biofilm. Les objectifs de notre travail étaient d'une part, d'étudier l'impact de ces stress sur le comportement de L. monocytogenes en milieu simulant le tfomage (bouillon de Richard) et sur Camembert et d'autre part, identifier les protéines impliquées par les stress de carence et/ou d'adhésion par une approche protéomique. L'application d'un traitement thermique (56ʿC/30 min) a détruit plus de 78% des cellules de L. monocytogenes. Les cellules survivantes n'ont acquis aucune résistance croisée à l'acide et se développent ou survivent moins bien dans les conditions (pH, ToC) de la production du Camembert. Les cellules issues d'un biofilm ont présenté une croissance plus rapide à 4ʿC et une acidorésistance accrue à pH 5 témoignant d'une physiologie propre à l'état adhérent. La carence a retardé la croissance des cellules à pH 7. Elle a augmenté (à l2ʿC) ou diminué (à 4ʿC) leur résistance à pH 5. D'après les fonctions des protéines induites identifiées, les cellules planctoniques carencées semblent orientées vers le maintien d'une activité métabolique minimum et l'acquisition de résistances. Les cellules du biofilm semblent être dans une dynamique de synthèse protéique, de division cellulaire et d'adaptation. Cetté étude contribue à la compréhension des mécanismes de survie de L. monocytogenes dans l'environnement et de leurs conséquences en production alimentaire.COMPIEGNE-BU (601592101) / SudocSudocFranceF

Préserver et exploiter la biodiversité des souches de bactéries pathogènes animales. Importance de la réglementation en vigueur

National audienc

Modulation de l'immunité innée moléculaire de l'oeuf

International audienc

Use of the collections of pathogenic bacteria from the Microbial Resource Centre CIRM-BP to evaluate the antibacterial potential of candidate molecules

International audienceThe International Centre for Microbial Resource dedicated to pathogenic bacteria (CIRM-BP) is located within the French National Institute for Agricultural Research (INRA) centre of Val de Loire. The activity of the CIRMBP is dedicated to the conservation and the distribution of strains of bacterial pathogens isolated from animals or from human as well as the distribution of their genomic DNAs. The CIRM-BP is ISO 9001 certified since 2008. Its collection comprises around 2500 strains belonging to 57 genera and 167 species of bacteria of risk groups 2 and 3. The CIRM-BP offers services related to strain identification, characterization and preservation. The CIRM-BP also develops scientific partnerships for studying biodiversity. Beside these activities, the CIRM-BP takes advantage of its collections of pathogenic strains to study the antibacterial potential of different molecules proposed by its collaborative partners. In that aim, a panel of pathogenic bacterial strains is first constituted considering the intended target for the candidate molecules (for example pathogenic bacteria specific of the production systems of farm animal). This leads to the choice of the bacterial species to be tested and of the strains, in function of their origin and context of isolation

Systemic administration of lipopolysaccharide in laying hens stimulates antimicrobial properties of egg white against Staphylococcus aureus

International audienceThe natural protective system of eggs relies on egg yolk immunoglobulins and on antimicrobial proteins/peptides mainly concentrated in the egg white. There is much evidence concerning the specific stimulation of immunoglobulins by antigens but to date, the influence of the hen milieu on the regulation of the egg innate molecular immunity has not been established. To explore the hypothesis of modulation in egg antimicrobial molecules, laying hens were immune-challenged with intravenous injections of Salmonella enterica Enteritidis lipopolysaccharide (LPS) at 24 h intervals. Eggs of the control and LPS groups were collected over a period of 21 days following the first LPS injection and the egg white activities against Staphylococcus aureus and Escherichia coli were assessed. The increase in egg white anti-S. aureus activity reached 20.9% and 23.4% (p<0.05) respectively on days 5 and 6 after the first LPS injection. Anti-E. coli activity increased moderately only on days 9 and 15 after the LPS treatment. To explore the origin of these increased antimicrobial activities, we analyzed the lysozyme and proteases inhibiting (anti-trypsin and anti-chymotrypsin) activities and the pH variations of egg whites. We recorded no significant variations between the two experimental groups for these potential modulating factors. Finally, using RT-qPCR we studied the expression of several genes coding for antimicrobial proteins and peptides involved in the immune response in the infundibulum and the magnum, Out of the 11 genes, only TLR4 in the magnum and ovocalyxin-36 in infundibulum were over-expressed respectively 24h and 8 days after the first LPS injection. The other candidate genes showed similar or down regulated expression in the LPS group as compared to the control especially during the first 24h. Our results suggest that the hen enhances the albumen antimicrobial activity of its eggs when exposed to immune stimulations or infections. This could be an attempt to preventively reinforce the protection of the embryo with nonspecific antimicrobial agents in addition to the specific antibodies exported to the egg. The origin of this stimulation of egg molecular immunity remains to be characterized amongst the numerous novel egg proteins recently identified

Microbial environment and immune challenge modulate the molecular innate defence of the hen egg

International audienc

Microbial environment of the hen modulates the innate immune defence of the egg against bacteria

International audienceThe egg is a complex formation that allows the development of an embryo ex utero by providing essential nutrients and a molecular protective system. In addition to immunoglobulins, molecular defences of the egg are also composed of antimicrobial peptides/proteins that are predominantly localized in egg white (EW). The present study investigated whether this innate antimicrobial protection is stimulated by the degree of contamination of the hen milieu by using two experimental models. Firstly, we compared the global antimicrobial activity of EW issued from hens reared in extreme bacterial environments: bacterial free (axenic, Ax), specific pathogen free (SPF) and standard (ST) conditions. EW issued from the ST and SPF groups demonstrated a greater inhibitory effect against Staphylococcus aureus as compared to those of Ax groups (9.8% and 4% respectively, P<0.05). The second approach explored the effect of an immune challenge in hens on the antimicrobial potential of EW. EW from hens stimulated with Salmonella Enteritidis lipopolysaccharide showed greater antimicrobial activity against Staphylococcus aureus (14.8%, P<O.OOI) than those of control hens. These results suggest that hens can reinforce the antimicrobial activity of the EW in response to immune stimulations induced by microbial contamination and anticipate the needs of the embryo in terms of protection. Further quantitative analyses of magnum gene expression and EW concentration of antimicrobial protein candidates were carried out to explore putative mechanisms of regulation

Genome sequences of 17 Pasteurella multocida strains involved in cases of rabbit Pasteurellosis

International audienceThis article reports draft genome sequences of 17 Pasteurella multocida strains isolated from naturally infected rabbits. The total lengths of the assembled contigs ranged between 2.21 and 2.48 Mb, and the total number of genes detected on the contigs ranged between 2,088 and 2,416

The CIRM in the new European landscape of biodiversity preservation: towards a deposition policy for INRA biological resources?

The Centre International de Ressources Microbiennes (CIRM) was created by INRA in 2004. The CIRM is now a network of five collections dedicated to the preservation, distribution and exploration of microbial biodiversity. It preserves more than 15,000 strains of plant, food and pathogenic bacteria, yeasts and filamentous fungi. CIRM is a Biological Research Center (BRC), ISO 9001 certified since 2008. The CIRM coordinated the European infrastructure project EMbaRC, which brought together 8 major microbial BRCs in Europe (www.embarc.eu). The CIRM is now partner of a larger infrastructure project established on the ESFRI roadmap, MIRRI (Microbial Resource Research Infrastructure). It includes over 70 microbial domain resource centers in 26 European countries (www.mirri.eu). Type strains are deposited in public collections under the pressure of journal editors and various international committees. However, despite the existence of dedicated BRCs, a very small proportion of published strains are deposited in such structures (1); this restricts further research and jeopardizes valorization of the biological material. To improve this situation, CIRM encourages strain deposit by INRA scientists. In return, CIRM ensures a high standard preservation and an enhanced visibility of the deposited material through its display in various databases (CIRM and FBRCMi databases, WFCC web site, StrainInfo.net…). In addition, CIRM also provides protection of the intellectual properties of the deposited material. Together with Inra scientists, CIRM therefore proposes to establish a deposition policy to improve the availability and visibility of INRA biological resources. This joint enterprise will constitute a strong example for the new landscape of European biodiversity preservation, which is currently being built in the MIRRI project