Diferenciación genética de poblaciones atlánticas de charcos de marea del copépodo intermareal Tigriopus brevicornis

The Harpacticoid copepod Tigriopus brevicornis belongs to the meiofauna of intertidal rock pools and is distributed widely along European coasts. Sixteen sites were sampled from the Irish Sea to the coasts of Spain. We used the ITS1 marker to analyse the relationship between the populations because it shows low intrapopulational variation (mean pairwise difference: 1.00 ± 0.8) and high interpopulational divergence (mean pairwise difference: 16.38 ± 7.39). A total of 57 bp out of 433 bp were recognised as informative nucleotides among the 61 individuals analysed. The analysis of the genetic relationships highlighted a north-south split in the distribution of the natural populations and showed a genetic break point around the Gironde estuary, which is probably due to differences in the geomorphologic characteristics of the coastal area on the two different sides of this estuary. Various populations were isolated and the ITS1 sequences indicated that there are specific genetic signatures in these populations. The northern set of populations, which was sampled along a large rocky coastline, had a metapopulation structure with genetic exchanges between geographically close populations and also between geographically far ones. The southern set of populations, which was sampled in small rocky pools on large sandy beaches, showed isolated populations as a consequence of the geomorphology of the area.Los copépodos harpacticoides Tigriopus brevicornis pertenecen a la meiofauna intermareal y están ampliamente distribuídos a lo largo de las costas europeas. Dieciséis lugares fueron muestreados desde el Mar de Irlanda hasta las costas de España. Nosotros usamos el marcador ITSI para analizar la relación entre poblaciones porque se mostró una variación interpoblacional baja (promedio diferencia de pares: 1.00 ± 0.8) y una divergencia interpoblacional alta (promedio diferencia de pares: 16.38 ± 7.39). Un total de 57 bp entre 433 bp fueron reconocidos como nucleótidos informativos entre los 61 individuos analizados. El análisis de relación genética resalta una partición Norte-Sur en la distribución de las poblaciones naturales y mostraba un punto de rotura genético alrededor del estuario de Gironde, probablemente debido a las diferencias en las características geomorfológicas de esta área costera en ambos lados del estuario. Algunas poblaciones fueron aisladas: las secuencias ITSI indicaban que había unas señales genéticas específicas en estas poblaciones. La población de la parte norte, que fue muestreada a lo largo de una línea rocosa de costa, evidencia la estructura de una metapoblación con intercambios genéticos entre poblaciones geográficamente próximas, pero también entre poblaciones geográficamente lejanas. La población de la parte sur, que fue muestreada en pequeños charcos de marea sobre vastas playas arenosas, mostraban poblaciones aisladas, destacando las consecuencias de la geomorfología del área

Probiotic potential of Enterococcus faecalis strains isolated from meconium

107 bacterial isolates with Gram positive staining and negative catalase activity, presumably assumed as LAB, were isolated from samples of meconium of six donors at Roubaix hospital, in the north of France. All these bacterial isolates were identified by MALDI-TOF mass spectrometry as Enterococcus faecalis. However, only six isolates among which E. faecalis 14, E. faecalis 28, E. faecalis 90, E. faecalis 97 and E. faecalis 101 (obtained from donor 3) and E. faecalis 93 (obtained from donor 5) were active against some Gram negative bacteria (GNB) and Gram positive bacteria (GPB), through production of lactic acid and bacteriocin like inhibitory substances (BLIS). The identification of these isolates was confirmed by 16rDNA sequencing and their genetic relatedness was established by REP-PCR and pulsed field gel electrophoresis (PFGE) methods. Importantly, the aforementioned antagonistic isolates were sensitive to various classes of antibiotics tested, exhibited high scores of coaggregation and hydrophobicity, and were not hemolytic. Taken together, these properties render these strains as potential candidates for probiotic applications

Antimicrobial activity of lipopeptide biosurfactants against foodborne pathogen and food spoilage microorganisms and their cytotoxicity

Lipopeptide biosurfactants produced by Bacillus sp. were assessed regarding their antimicrobial activity against foodborne pathogenic and food spoilage microorganisms. Both Gram-positive and Gram-negative bacteria were found not to be susceptible to these lipopeptides. However, mycosubtilin and mycosubtilin/surfactin mixtures were very active against the filamentous fungi Paecilomyces variotti and Byssochlamys fulva, with minimum inhibitory concentrations (MICs) of 1-16 mg/L. They were also active against Candida krusei, MIC= 16-64 mg/L. Moreover it was found that the antifungal activity of these lipopeptides produced at semi-industrial scale was not affected by differences in isoform composition (as from different batches) and/or purity. Furthermore their cytotoxicity tested on two different cell lines mimicking ingestion and detoxification was comparable to those of approved food preservatives such as nisin. Overall, for the first time here mycosubtilin and mycosubtilin/surfactin mixtures were found to have high antifungal activity against food relevant fungi at concentrations lower than their toxicity level hence, suggesting their application for extending the shelf-life of products susceptible to these moulds. In addition combining nisin with mycosubtilin or mycosubtiliin/surfactin mixtures proved to be an effective approach to produce antimicrobials with broader spectrum of action

Peptides from fish and crustacean by-products hydrolysates stimulate cholecystokinin release in STC-1 cells

International audienceFish protein hydrolysates (FPH) are of significant interest, due to their potential application as a source of bioactive peptides in nutraceutical and pharmaceutical domains. Here, we investigated the action of FPH from blue whiting (Micromesistius poutassou) and brown shrimp (Penaeus aztecus) on cholecystokinin release from intestinal endocrine cells (STC-1). We demonstrated for the first time that FPH were able to highly stimulate CCK-releasing activity from STC-1 cells and that this stimulation was mainly due to peptide molecules. The partial purification of CCK-stimulating peptides showed that their apparent molecular weight ranged between 1000 and 1500 Da for fish and crustacean FPH, respectively. Finally, in an aim to industrially produce hydrolysates enriched in CCK-stimulating molecules, we tested the effects of membrane processes (ultrafiltration and nanofiltration) on active peptide enrichment

BioacPepFinder: Novel Bioinformatics Tool for the Discovery of Bioactive Peptides from Protein Digestion.

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Bioactivities of hemorphins released from bovine haemoglobin gastrointestinal digestion: Dual effects on intestinal hormones and DPP-IV regulations

International audienceFood-derived hemorphins were studied for their interactions with intestinal cells in relation to food intake regulations. LLW-H4, LW-H4, VV-H4, W-H7 and H7 were identified in the 2 h-intestinal hydrolysate of haemoglobin simulated gastrointestinal digestion and synthesised. These food-derived hemorphins showed secretagogue properties of the anorexigenic hormones cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1) when in contact with murine STC-1 cells. They did not show significant modulatory effect on the corresponding prohormones mRNA levels. However, they downregulated the enzyme PC1 that processes proglucagon into GLP-1 specifically in the intestine. Moreover, VV-H4, VV-H7 & H7 were potent inhibitors of the GLP-1 inactivating dipeptidyl-peptidase IV (DPP-IV) and transiently upregulated its mRNA in human Caco-2 cells. These results suggest that food-derived hemorphins display dual luminal effects that participate at different levels in food intake and glycaemia regulation and add to the known roles of the special class of food-derived opioid peptides, the hemorphins

In vitro probiotic properties of selected lactobacilli and multi-strain consortium on immune function, gut barrier strengthening and gut hormone secretion

International audienceLactobacillus reuteri ICVB395, L. gasseri ICVB392 and L. gasseri ICVB396 strains, isolated from vaginal microbiota, were investigated for their probiotic traits. L. reuteri ICVB395 strain and the 3RG consortium, associating these three Lactobacillus strains, showed the best anti-inflammatory profile on peripheral blood mononuclear cell (PBMC) while L. gasseri ICVB392 was the most potent together with the 3RG consortium to strengthen a Caco-2-derived epithelial barrier. The three studied strains induced various secretion levels of glucagon-like peptide 1 (GLP-1) and cholecystokinin (CCK) by STC-1 enteroendocrine cells, whereas the 3RG consortium was globally less performing. Specific antagonists of protein G receptors, CaSR (Calcium-Sensing Receptor) and GPRC6A (G protein-coupled receptor family C group 6 member A), and inhibitor of the peptide transporter Pept-1 provoked differential modulation of the GLP-1 and CCK secretion by STC-1 cells, indicating that different mechanisms are involved in the capacity of lactobacilli and the 3RG to modulate gut hormones secretion