Modélisation de l'entretien du paysage par des herbivores en moyenne montagne : une approche multi-agents

L'abandon de l'utilisation des ressources herbagères par l'activité pastorale entraîne un appauvrissement de la diversité écologique et spécifique. A terme, cette évolution se traduit par le déplacement des activités humaines hors de ces zones et à un déséquilibre au niveau du territoire national. Un programme de recherche pluridisciplinaire, dans le cadre d'un Groupement d'intérêt Scientifique, a été mis en place dès 1994 pour élaborer de nouveaux modes de gestion qui concilient production agricole et entretien de l'espace en condition de sous chargement (peu d'animaux par unité de surface). Cet article s'inscrit dans une démarche d'acquisition de méthodes afin d'expérimenter des techniques de gestion de pâturage mixte bovins et chevaux selon une hypothèse de complémentarité entre ces deux espèces. La partie informatique présentée vise à simuler les dynamiques animales, végétales et paysagères futures et, à terme, proposer des protocoles de gestion aptes à répondre à ces nouvelles demandes. L'objectif de la modélisation que nous présentons est de simuler le fonctionnement de l'estive, afin de comprendre l'interaction entre l'évolution de la végétation, les déplacements et les actions des animaux en pâture. Un des modes de simulation utilise un système multi-agents. Le modèle conceptuel de la simulation est en cours de validation, il a été formalisé avec la notation graphique du langage de modélisation unifié (UML) et la version actuelle du logiciel est implémentée avec le langage de programmation Java. Pour suivre et enregistrer les localisations des animaux sur le terrain, ceux-ci sont équipés d'un récepteur satellite GPS (Global Positioning System). L'activité de pâturage des animaux est enregistrée par des colliers Ethosys. / The surrender of herbaceous resources by the grazing activity results in an impoverishment of both ecological and specific diversity. On the long term, this trend imposes the localization of human activities far from these zones and a national imbalance. A multidisciplinary research program was set up in 1994 with the aim of elaborating new ways of management, which would contribute to maintain both the productivity and the opened landscapes within the condition of low grazing pressure. This paper exposes the methods we elaborated in order to test several management techniques of grasslands by mean of cattle and horses within the hypothesis of complementarity between these two species. The computer science part of this paper presents the results of simulations of future dynamic behaviors of the animals, vegetation and landscape, in order to propound some management protocols. The simulator is based on a multi-agent system. The conceptual model, formalized with Unified Modeling Language graphical notation is actually in validation phase and the implementation of the software was done in the Java programming language. The following of the animals in the field was done by means of GPS equipments and the animal activity was recorded by Ethosys equipments

Lactobacillus reuteri CRL 1098 and Lactobacillus acidophilus CRL 1014 differently reduce in vitro immunotoxic effect induced by Ochratoxin A

Ochratoxin A (OTA) is a widespread mycotoxin contaminating several food products which causes detrimental health effects. The ability of Lactobacillus reuteri CRL 1098 and Lactobacillus acidophilus CRL 1014 to prevent OTA effects on TNF-α and IL-10 production and apoptosis induction in human peripheral blood mononuclear cells (PBMC) was investigated. Membrane rafts participation in these responses was also evaluated. L. reuteri reduced by 29% the OTA inhibition of TNF-α production whereas L. acidophilus increased 8 times the TNF-α production by OTA treated-PBMC. Also, both bacteria reversed apoptosis induced by OTA by 32%. However, neither of the bacteria reversed the OTA inhibition on IL-10 production. On the other hand, the lactobacilli were less effective to reverse OTA effects on disrupted-rafts PBMC. This study shows that two lactobacilli strains can reduce some negative OTA effects, being membrane rafts integrity necessary to obtain better results. Also, the results highlight the potential capacity of some lactobacilli strains usually included in natural dietary components in milk-derived products and cereals feed, to reduce OTA toxicity once ingested by humans or animals.Fil: Mechoud, Monica Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Juarez, Guillermo Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Rodriguez, Ana Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

Disruption of lipid rafts enhances the effect of lactobacilli on the production of tumor necrosis factor-alpha in mononuclear blood cells

We investigated, to determine whether disruption of lipid rafts would influence the effect of three selected strains of Lactobacillus on TNF-alpha production by peripheral blood mononuclear cells. Two strains increased TNF-alpha production; and the third one reduced cytokine levels. Disruption of rafts changed the immunomodulatory effect of the three strains. This is the first report on a potential role of rafts in lactobacilli-cell interaction.Fil: Soria, Mario Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Mechoud, Monica Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Martin de Quevedo, Angela. Laboratorio Quevedo; ArgentinaFil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Rodriguez, Ana Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

Methods to mitigate Escherichia coli blooms in human ex vivo colon model experiments using the high throughput micro-Matrix bioreactor fermentation system

Ex vivo colon model experiments are frequently employed as a means to assess the gut microbiome modulating potential of different foods, food ingredients and dietary supplements. A number of useful models already exist; however, they tend to be relatively low in terms of throughput (3–4 samples per experiment) with a long experiment duration of one to a number of weeks. Therefore, a need for a high-throughput system with a short duration time is required to enable screening of large numbers of samples. Therefore, we report here on the development of a system based on the Applikon micro-Matrix bioreactor which has the capacity to run 24 samples with an experiment duration of 48 h. However, Escherichia coli blooms are a common problem encountered in this model. Here, we describe the factors that contribute to such blooms and provide approaches to address them, providing: • Step by step optimisation of processes involved in conducting ex vivo distal colon experiments using the micro-Matrix bioreactor fermentation platform • Recommended steps for users on how to attenuate E. coli blooms in such ex vivo colon model experiments

Lactobacillus reuteri CRL1098 soluble factors modulate tumor necrosis factor alpha production in peripheral blood mononuclear cells: involvement of lipid rafts

The aim of the present study was to evaluate the capacity of Lactobacillus reuteri CRL1098 soluble factors (Lr-S) to modulate TNF-α production in peripheral blood mononuclear cells (PBMC) and to study lipid rafts participation in this response. PBMC treated with Lr-S showed a reduced production of TNF-α. In addition, Lr-S treatment activated ERK and p38 MAPK pathways in PBMC. Lipid rafts participation in the reduced production of TNF-α by PBMC induced by Lr-S was verified by lipid rafts disruption with methyl-β-cyclodextrin and the reduction of the Src-tyrosine kinase Lck localization in rafts. Moreover, PBMC pre-treatment with Lck inhibitors blocked the effect of Lr-S on TNF-α production suggesting that activation and mobilization of Lck from lipid rafts would be involved in the modulatory effect of L. reuteri CRL1098. A secreted peptide of 5785 Da would be responsible of the modulatory effect of CRL1098 strain. This study demonstrated for the first time the lipid rafts participation in a response induced by a beneficial bacterium. Also, these results open new possibilities for investigating the molecular mechanisms involved in the interaction of probiotic bacterial extracellular compounds with immune cells.Fil: Mechoud, Monica Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Mateos, Melina Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Villena, Julio Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Salvador, Gabriela Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Rodriguez, Ana Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

Sakacin G is the main responsible bacteriocin for the anti-listerial activity of meat-borne Lactobacillus curvatus ACU-1

The present study was conducted to quantify the expression of the sakacins produced by Lactobacillus curvatus ACU-1, a strain isolated from artisanal dry fermented sausages of Argentina. Polymerase chain reaction (PCR) screening indicated the presence of sakacin G, P, and Q genes in L. curvatus ACU-1. Purification and activity assays determined that anti-Listeria activity was mainly associated to sakacin G, as mass spectrometry analysis revealed a single peak of 3832.60 Da. Further characterization by quantitative PCR demonstrated that L. curvatus ACU-1 transcription of the sakacin G structural gene was three orders of magnitude higher than the others. Interestingly, L. curvatus ACU-1 had skgA1/skgA2 as well as sppQ genes encoded in a plasmid, while the sppA gene that encodes for sakacin P was present in the bacterial chromosome. These results point out that sakacin G is the main peptide responsible for the anti-listerial activity of L. curvatus ACU-1, with little or no contribution of sakacin P and sakacin Q. The high level of expression of sakacin G demonstrated in the present work would facilitate its potential use in food preservation, improving the food quality, safety, and shelf life. In addition, the sakacin G promoter may serve as an interesting tool for the expression of other bacteriocins at higher levels.Fil: Mechoud, Monica Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Alvarez, Ornella Estefanía. Universidad Nacional del Chaco Austral; ArgentinaFil: Cayre, María Elisa. Universidad Nacional del Chaco Austral; ArgentinaFil: Castro, Marcela Paola. Universidad Nacional del Chaco Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Minahk, Carlos Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Saavedra, Maria Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

Ferulic Acid Esterase Producing Lactobacillus johnsonii from Goat Feces as Corn Silage Inoculants

Ferulic acid esterase (FAE+)-producing lactobacilli are being studied as silage inoculants due to their potential of increasing forage fiber digestibility. In this work, three FAE+ Lactobacillus (L.) johnsonii strains were isolated from caprine feces and characterized according to their potential probiotic characteristics and as silage inoculants. Limosilactobacillus fermentum CRL1446, a human probiotic isolated from goat cheese, was also included in the experiments as a potential silage inoculant. FAE activity quantification, probiotic characterization, and growth in maize aqueous extract indicated that L. johnsonii ETC187 might have a better inoculant and probiotic aptitude. Nevertheless, results in whole-corn mini silos indicated that, although acid detergent fiber (ADF) was significantly reduced by this strain (3% compared with the uninoculated (UN) group), L. johnsonii ETC150 and CRL1446 not only induced similar ADF reduction but also reduced dry matter (DM) loss (by 7.3% and 6.5%, respectively) compared with the UN group. Additionally, CRL1446 increased in vitro DM degradability by 10%. All treatments reduced gas losses when compared with the UN group. The potential probiotic features of these strains, as well as their beneficial impact on corn fermentation shown in this study, encourage further studies as enhancers in animal production