Publications by authors named "Pilet M"

Biopreservation is a sustainable approach to improve food safety and maintain or extend food shelf life by using beneficial microorganisms or their metabolites. Over the past 20 years, omics techniques have revolutionised food microbiology including biopreservation. A range of methods including genomics, transcriptomics, proteomics, metabolomics and meta-omics derivatives have highlighted the potential of biopreservation to improve the microbial safety of various foods.

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Lightly preserved seafood products, such as cold-smoked fish and fish gravlax, are traditionally consumed in Europe and are of considerable economic importance. This work aimed to compare three products that were obtained from the same batch of fish: cold-smoked salmon (CSS) stored under vacuum packaging (VP) or a modified atmosphere packaging (MAP) and VP salmon dill gravlax (SG). Classical microbiological analyses and 16S rRNA metabarcoding, biochemical analyses (trimethylamine, total volatile basic nitrogen (TVBN), biogenic amines, pH, volatile organic compounds (VOCs)) and sensory analyses (quantitative descriptive analysis) were performed on each product throughout their storage at a chilled temperature.

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Seafood and fishery products are very perishable commodities with short shelf-lives owing to rapid deterioration of their organoleptic and microbiological quality. Microbial growth and activity are responsible for up to 25% of food losses in the fishery industry. In this context and to meet consumer demand for minimally processed food, developing mild preservation technologies such as biopreservation represents a major challenge.

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Microbial food spoilage is responsible for significant economic losses. Brochothrix thermosphacta is one of the major bacteria involved in the spoilage of meat and seafood. Its growth and metabolic activities during food storage result in the production of metabolites associated with off-odors.

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The microbiota of fresh French pork sausages were characterised in five batches of comminuted pork meat that were equally divided into two formulations either containing the acid-based preservatives lactate and acetate, or no preservatives. Conventional microbiological analysis and high-throughput 16S rDNA amplicon sequencing methods were performed on meat batches packed under modified atmosphere (70% oxygen and 30% carbon dioxide) during chilled storage. In addition, meat pH and colour, and gas composition of the packages were monitored until the end of the shelf-life.

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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%). CNCM I-4031 has the capacity to prevent the growth of in contaminated peeled and cooked shrimp and in a chemically defined medium using a cell-to-cell contact-dependent mechanism.

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The development of a multi-omics approach has provided a new approach to the investigation of microbial communities allowing an integration of data, which can be used to better understand the behaviour of and interactions between community members. Metagenomics, metatranscriptomics, metaproteomics and metabolomics have the potential of producing a large amount of data in a very short time, however an important challenge is how to exploit and interpret these data to assist risk managers in food safety and quality decisions. This can be achieved by integrating multi-omics data in microbiological risk assessment.

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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.

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Tropical shrimp is of considerable economic importance in the world 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.

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In this study, we present the draft genome sequence of Carnobacterium divergens V41. This strain was previously reported as producing divercin V41, a bacteriocin of interest for food biopreservation. Its genome revealed also the presence of a gene cluster putatively involved in polyketide production, which is unique in lactic acid bacteria.

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The pathogenesis of listeriosis results mainly from the ability of Listeria monocytogenes to attach, invade, replicate and survive within various cell types in mammalian tissues. In this work, the effect of two bacteriocin-producing Carnobacterium (C. divergens V41 and C.

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The genus Lactococcus comprises 12 species, some known for decades and others more recently described. Lactococcus piscium, isolated in 1990 from rainbow trout, is a psychrotrophic lactic acid bacterium, 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.

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Aphanomyces euteiches Drechsler is a serious pathogen of leguminous crops that causes devastating root rot of pea worldwide. Given that A. euteiches is a diploid organism, robust, codominant markers are needed for population genetics studies.

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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.

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Histamine fish poisoning is common and due to toxic concentrations of histamine often produced by Gram-negative bacteria in fin-fish products with a high content of the free amino acid histidine. The genus Morganella includes two species previously reported to cause incidents of histamine fish poisoning. Morganella morganii and Morganella psychrotolerans are both strong producer of histamine.

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Most food products are highly perishable as they constitute a rich nutrient source for microbial development. Among the microorganisms contaminating food, some present metabolic activities leading to spoilage. In addition to hygienic rules to reduce contamination, various treatments are applied during production and storage to avoid the growth of unwanted microbes.

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The microbial spoilage of meat and seafood products with short shelf lives is responsible for a significant amount of food waste. Food spoilage is a very heterogeneous process, involving the growth of various, poorly characterized bacterial communities. In this study, we conducted 16S ribosomal RNA gene pyrosequencing on 160 samples of fresh and spoiled foods to comparatively explore the bacterial communities associated with four meat products and four seafood products that are among the most consumed food items in Europe.

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The spoilage potential of isolates belonging to five bacterial groups/species (Shewanella baltica, Carnobacterium maltaromaticum, Aeromonas salmonicida, Vibrio sp., "other Gamma-Proteobacteria" [containing one strain of Pseudoalteromonas sp. and one strain of Psychrobacter sp.

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A specific real-time PCR quantification method combined with a propidium monoazide sample treatment step was developed to determine quantitatively the viable population of the Photobacterium phosphoreum species group in raw modified-atmosphere-packed salmon. Primers were designed to amplify a 350-bp fragment of the gyrase subunit B gene (gyrB) of P. phosphoreum.

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The spoilage potential of eight bacterial groups/species (Serratia spp., Hafnia alvei, Brochothrix thermosphacta, Carnobacterium maltaromaticum, Shewanella baltica, Lactococcus piscium, Photobacterium phosphoreum, "other Enterobacteriaceae" [containing one strain of Moellerella sp., Morganella sp.

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Strain SMXD51, isolated from chicken ceca and identified as Lactobacillus salivarius, produced a component that inhibits the growth of Gram-positive and Gram-negative bacteria and especially Campylobacter jejuni. The active peptide from the cell-free supernatant of Lb. salivarius SMXD51 was purified in three steps: (i) precipitation with 80% saturated ammonium sulfate, (ii) elution on a reversed phase SPE UPTI-CLEAN cartridge using different concentrations of acetonitrile, (iii) final purification by reversed phase HPLC on a C(18) column.

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The maximum specific growth rate (μ(max)) of Brochothrix thermosphacta, a spoilage bacteria of cooked peeled shrimp, and Lactococcus piscium CNCM I-4031, a bioprotective strain, was investigated under different conditions of temperature, NaCl concentrations and pH. The basic modelling approach used was the Gamma concept (γ-concept) and the model developed was then adapted to shrimp. Cardinal growth parameters were quite similar for the two strains, except for NaCl.

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Brochothrix thermosphacta, a Gram-positive bacterium, is considered as the predominant spoilage microbiota of modified atmosphere packing (MAP) shrimp and fish. Traditional methods currently used to detect B. thermosphacta in foods are time-consuming and labour-intensive.

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In order to characterise the spoilage related to microbiota of raw salmon, a combination of culture-dependent and -independent methods, including PCR-TTGE, was used to analyse 3 raw salmon batches stored for 3 days at chilled temperature in modified atmosphere packaging (MAP) (50% CO₂/50% N₂) or under vacuum. Sensory evaluation, microbiological enumeration and chemical analysis were performed after 3, 7 and 10 days of storage. At the onset of spoilage, 65 bacterial isolates were picked from the plates.

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This study investigated the sensory quality and physicochemical evolution (pH, glucose, l-lactic acid, biogenic amine, free amino-acids and volatile compounds) during storage at 8°C of cooked peeled shrimp inoculated with the specific spoilage bacteria Brochothrix thermosphacta alone or mixed with the protective strain Lactococcus piscium CNCM I-4031. Growth of both bacteria was monitored at regular intervals during storage by microbial counts and the thermal temperature gradient gel electrophoresis (TTGE) technique. Bacterial counts showed that L.

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