Bioprotective Effect of Lactococcus piscium CNCM I-4031 Against Listeria monocytogenes Growth and Virulence

Listeria monocytogenes is a Gram-positive pathogen occurring in many refrigerated ready-to-eat foods. It is responsible for foodborne listeriosis, a rare but severe disease with a high mortality rate (20–30%). Lactococcus piscium CNCM I-4031 has the capacity to prevent the growth of L. monocytogenes in contaminated peeled and cooked shrimp and in a chemically defined medium using a cell-to-cell contact-dependent mechanism. To characterize this inhibition further, the effect of L. piscium was tested on a collection of 42 L. monocytogenes strains. All strains were inhibited but had different sensitivities. The effect of the initial concentration of the protective and the target bacteria revealed that the inhibition always occurred when L. piscium had reached its maximum population density, whatever the initial concentration of the protective bacteria. Viewed by scanning electron microscopy, L. monocytogenes cell shape and surface appeared modified in co-culture with L. piscium CNCM I-4031. Lastly, L. monocytogenes virulence, evaluated by a plaque-forming assay on the HT-29 cell line, was reduced after cell pre-treatment by the protective bacteria. In conclusion, the bioprotective effect of L. piscium toward L. monocytogenes growth and virulence was demonstrated, and a hypothesis for the inhibition mechanism is put forward

Lactococcus piscium : a psychotrophic lactic acid bacterium with bioprotective or spoilage activity in food - a review

The genus Lactococcus comprises twelve species, some known for decades and others more recently described. Lactococcus piscium, isolated in 1990 from rainbow trout, is a psychrotrophic lactic acid bacterium (LAB), probably disregarded because most of the strains are unable to grow at 30°C. During the last 10 years, this species has been isolated from a large variety of food: meat, seafood and vegetables, mostly packed under vacuum (VP) or modified atmosphere (MAP) and stored at chilled temperature. Recently, culture-independent techniques used for characterization of microbial ecosystems have highlighted the importance of L. piscium in food. Its role in food spoilage varies according to the strain and the food matrix. However, most studies have indicated that L. piscium spoils meat, whereas it does not degrade the sensory properties of seafood. L. piscium strains have a large antimicrobial spectrum, including Gram-positive and negative bacteria. In various seafood, some strains have a protective effect against spoilage and can extend the sensory shelf-life of the products. They can also inhibit the growth of Listeria monocytogenes, by a cell-to-cell contact-dependent. This article reviews the physiological and genomic characteristics of L. piscium and discusses its spoilage or protective activities in food

Lutte contre les mammites : La piste des probiotiques Identification des espèces de bactéries lactiquesassociées à l'écosystème mammaire des bovins laitiers biologiques en vue de développer un probiotiquemammaire

Directeur de PublicationPascal Le Guern, administrateur référent du Pôle "Recherche-expérimentation"il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : REPORTabsen

Lutte contre les mammites : La piste des probiotiques Identification des espèces de bactéries lactiques associées à l'écosystème mammaire des bovins laitiers biologiques en vue de développer un probiotique mammaire

Directeur de PublicationPascal Le Guern, administrateur référent du Pôle "Recherche-expérimentation"il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : REPORTabsen

Improving simultaneously the quality and safety of cooked and peeled shrimp using a cocktail of bioprotective lactic acid bacteria

Tropical shrimp is of considerable economic importance in the word but is highly perishable due to microbial and chemical degradation. Biopreservation is a food preservation technology based on the addition of “positive” bacteria able to kill or prevent the growth of undesirable microorganisms. Two strains of lactic acid bacteria (LAB) have previously been selected for a biopreservation strategy: Lactococcus piscium CNCM I-4031, for its ability to prevent the sensory deterioration of seafood and Carnobacterium divergens V41, which inhibits growth of Listeria monocytogenes. The objective was to test the association of the two strains to improve both the quality and safety of shrimp. In a first trial, the two LAB were inoculated alone or in a cocktail in cooked and peeled shrimp (CPS) Penaeus vannamei at 5 × 105 CFU/g. Chemical, sensory and microbiological analyses by culture-dependent and -independent methods were performed during storage under modified atmosphere packaging (MAP) at 8 °C. The results were compared to a non-inoculated batch. In a second trial, the same experiments were repeated in the presence of 102 CFU/g of L. monocytogenes RF191. The microbiota of CPS was composed of LAB, Shewanella spp. and Enterobacteriaceae. Brochothrix thermosphacta was not detected. L. piscium and C. divergens reached 108 and 109 CFU/g, respectively, in 7 days and did not inhibit each other when co-inoculated. L. piscium reduced L. monocytogenes by 1 Log (CFU/g) for 28 days. C. divergens had an immediate listericidal effect lasting 7 days. A regrowth of L. monocytogenes was then observed but the count was always 2 to 5 Log (CFU/g) lower than in the control. No additional or synergic effect between protective strains was observed and the cocktail had the same inhibitory effect as C. divergens alone. C. divergens was very effective at preventing the sensory deterioration of CPS. This may be related to the inhibition of Shewanella and Enterobacteriaceae. However, the panelists could detect the presence of C.divergens during the first 10 days of storage, with slight unpleasant odors and flavors. L. piscium improved the sensory quality of CPS for 14 days only. In co-culture, L. piscium eliminated the off-odors and flavors released by C. divergens in the early stage of storage and the co-culture allowed maintaining a good quality of CPS throughout the storage. Therefore, the use of a cocktail of L. piscium CNCM I-4031 and C. divergens V41 is recommended in a strategy of biopreservation of shrimp

Inhibition mechanism of Listeria monocytogenes by a bioprotective bacteria Lactococcus piscium CNCM I-4031

Listeria monocytogenes is a pathogenic Gram positive bacterium and the etiologic agent of listeriosis, a severe food-borne disease. Lactococcus piscium CNCM I-4031 has the capacity to prevent the growth of L. monocytogenes in contaminated peeled and cooked shrimp. To investigate the inhibititory mechanism, a chemically defined medium (MSMA) based on shrimp composition and reproducing the inhibition observed in shrimp was developed. In co-culture at 26°C, L. monocytogenes was reduced by 3-4 log CFU g-1 after 24 h. We have demonstrated that the inhibition was not due to secretion of extracellular antimicrobial compounds as bacteriocins, organic acids and hydrogen peroxide. Global metabolomic fingerprints of these strains in pure culture were assessed by liquid chromatography coupled with high resolution mass spectrometry. Consumption of glucose, amino-acids, vitamins, nitrogen bases, iron and magnesium was measured and competition for some molecules could be hypothesized. However, after 24 h of co-culture, when inhibition of L. monocytogenes occurred, supplementation of the medium with these compounds did not restore its growth. The inhibition was observed in co-culture but not in diffusion chamber when species were separated by a filter membrane. Taken together, these data indicate that the inhibition mechanism of L. monocytogenes by L. piscium is cell-to-cell contact-dependent

Lactobacillus rhamnosus Lcr35 en tant que traitement efficace contre l'infection à Candida albicans dans le modèle préclinique Caenorhabditis elegans

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Lactobacillus rhamnosus Lcr35 as an effective treatment for preventing Candida albicans infection in the preclinical model Caenorhabditis elegans

International audienceIntroduction and aimsThe increased recurrence of Candida albicans infections is associated with greater resistance to antifungal drugs. This involves the establishment of alternative therapeutic protocols such as the use of probiotic microorganisms whose antifungal potential has already been demonstrated using preclinical models (cell cultures, laboratory animals) and clinical studies. Understanding the mechanisms of action of probiotic microorganisms has become a strategic need for the development of new therapeutics for humans. In this study, we investigated the prophylactic anti-Candida albicans properties of Lactobacillus rhamnosus Lcr35® using the in vivo Caenorhabditis elegans model. Materials and methodsFor this, we followed the survival of the nematode in the case of a fungal infection, prevented or not by the probiotic Lcr35®. This followed by a gene expression analysis. Also, we are interested in the localization of the DAF-16 transcription factor.Results, discussion and conclusionOn the top of having a pro-longevity activity in the nematode, Lcr35® protects the animal from the fungal infection even if the yeast is still detectable in its intestine. At the mechanistic level, we note the repression of genes of the p38 MAPK signaling pathway and genes involved in the antifungal response induced by Lcr35® suggesting that the pathogen no longer appears to be detected by the worm immune system. However, the DAF-16 / FOXO transcription factor, implicated in the longevity and antipathogenic response of C. elegans, is activated by Lcr35®. These results suggest that the probiotic strain acts by stimulating its host via DAF-16, but also by suppressing the virulence of the pathogen. However, for more precision, an exhaustive study of the C. elegans transcriptome will be carried out in order to decipher the mechanisms of action of Lcr35®

Lactobacillus rhamnosus Lcr35® as an effective treatment for preventing Candida albicans infection in the preclinical model Caenorhabditis elegans

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Complete Genome Sequence of Lactococcus piscium CNCM I-4031, a Bioprotective Strain for Seafood Products

Lactococcus piscium CNCM I-4031 is a psychotrophic foodborne lactic acid bacterium showing potential interest for the biopreservation of seafood products due to its inhibition properties toward pathogenic and spoilage bacteria. The analysis of its genome will provide a better understanding of the mechanisms of interaction between these bacteria