Publications by authors named "Celine Delbes"

An exhaustive analysis was performed on more than 2000 microbiotas from French Protected Designation of Origin (PDO) cheeses, covering most cheese families produced throughout the world. Thanks to a complete and accurate set of associated metadata, we have carried out a deep analysis of the ecological drivers of microbial communities in milk and "terroir" cheeses. We show that bacterial and fungal microbiota from milk differed significantly across dairy species while sharing a core microbiome consisting of four microbial species.

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The supplementation of animal feed with microbial additives remains questioning for the traditional or quality label raw milk cheeses with regard to microbial transfer to milk. We evaluated the effect of dietary administration of live yeast on performance and microbiota of raw milk, teat skin, and bedding material of dairy cows. Two balanced groups of cows (21 primiparous 114 ± 24 DIM, 18 multiparous 115 ± 33 DIM) received either a concentrate supplemented with CNCM I-1077 (1 × 10 CFU/d) during four months (LY group) or no live yeast (C group).

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A previous study identified differences in rind aspects between -type cheeses manufactured from the same skimmed milk, supplemented with cream derived either from pasture-raised cows (P) or from cows fed with maize silage (M). Using an integrated analysis of multiomic data, the present study aimed at investigating potential correlations between cream origin and metagenomic, lipidomic and volatolomic profiles of these cheeses. Fungal and bacterial communities of cheese cores and rinds were characterized using DNA metabarcoding at different ripening times.

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Adding massive amounts of lactic starters to raw milk to manage the sanitary risk in the cheese-making process could be detrimental to microbial diversity. Adjusting the amount of the lactic starter used could be a key to manage these adverse impacts. In uncooked pressed cheeses, we investigated the impacts of varying the doses of a lactic starter (the recommended one, 1×, a 0.

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The development of powerful sequencing techniques has allowed, albeit with some biases, the identification and inventory of complex microbial communities that inhabit different body sites or body fluids, some of which were previously considered sterile. Notably, milk is now considered to host a complex microbial community with great diversity. Milk microbiota is now well documented in various hosts.

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Background: Reads assignment to taxonomic units is a key step in microbiome analysis pipelines. To date, accurate taxonomy annotation of 16S reads, particularly at species rank, is still challenging due to the short size of read sequences and differently curated classification databases. The close phylogenetic relationship between species encountered in dairy products, however, makes it crucial to annotate species accurately to achieve sufficient phylogenetic resolution for further downstream ecological studies or for food diagnostics.

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Although the effects of cow diet on cheese sensory properties have been well documented, the putative interactions between the biochemical and microbial milk components and their respective roles in the development of the sensory properties of cheeses have yet to be explored in depth. The aim of this study was to evaluate the specific contribution of milk fat composition to the formation of cheese sensory properties. Two creams with different fat compositions were obtained from cows fed either pasture or maize silage.

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Background: Staphylococcus aureus is an important foodborne pathogen. Lactococcus garvieae is a lactic acid bacterium found in dairy products; some of its strains are able to inhibit S. aureus growth by producing HO.

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The objectives of this study were to explore bacterial community assembly from cow teat skin to raw milk cheeses and to evaluate the role of farming systems on this assembly using 16S rRNA gene high-throughput sequencing. The two grazing systems studied (extensive vs. semi-extensive) had a greater effect on the microbiota of cow teat skin than on that of raw milks and cheeses.

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The bio-preservation potential of lies in its capacity to inhibit the growth of , especially , in dairy products and . , inhibition is modulated by the level of aeration, owing to hydrogen peroxide (HO) production by under aeration. The response to this inhibition has already been studied.

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Growth of the foodborne pathogen Staphylococcus aureus can be inhibited in milk and in cheese by the hydrogen peroxide-producing Lactococcus garvieae N201 dairy strain. Transcriptomic responses of two S. aureus strains, the S.

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Background: Microbial communities of traditional cheeses are complex and insufficiently characterized. The origin, safety and functional role in cheese making of these microbial communities are still not well understood. Metagenomic analysis of these communities by high throughput shotgun sequencing is a promising approach to characterize their genomic and functional profiles.

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The microbiological quality, safety, and composition of mixtures of ewe's and goat's milk (90:10) used for cheesemaking were evaluated before and after thermization at 60 and 67 degrees C for 30 s. Such mild thermal treatments are commonly applied to reduce natural contaminants of raw milk before processing for traditional hard Greek cheeses. Raw milk samples had an average total bacterial count of 7.

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The link between milk production practices and bacterial diversity of 67 raw milks from dairy farms in the Savoie and Haute-Savoie regions of France was studied by Single Strand Conformation Polymorphism (SSCP) analysis. The milking practices and the cleanliness of different parts of the cow housing were evaluated. The SSCP bacterial profiles allow to classify the 67 milks into three groups: group A was characterised by a majority of Gram-positive non-lactic acid bacteria (Corynebacterineae and Micrococcaceae) and a high level of hygiene in milking practices.

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The microbial communities in milks from one herd were evaluated during 1-year of lactation, using molecular methods to evaluate their stability and the effect of breeding conditions on their composition. The diversity of microbial communities was measured using two approaches: molecular identification by 16S and 18S rDNA sequencing of isolates from counting media (two milks), and direct identification using 16S rDNA from clone libraries (six milks). The stability of these communities was evaluated by counting on selective media and by Single Strand Conformation Polymorphism (SSCP) analysis of variable region V3 of the 16S rRNA gene and variable region V4 of the 18S rRNA gene.

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The diversity and dynamics of bacterial populations in Saint-Nectaire, a raw-milk, semihard cheese, were investigated using a dual culture-dependent and direct molecular approach combining single-strand conformation polymorphism (SSCP) fingerprinting and sequencing of 16S rRNA genes. The dominant clones, among 125 16S rRNA genes isolated from milk, belonged to members of the Firmicutes (58% of the total clones) affiliated mainly with the orders Clostridiales and the Lactobacillales, followed by the phyla Proteobacteria (21.6%), Actinobacteria (16.

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Staphylococcus aureus growth and enterotoxin production during the manufacture of model Saint-Nectaire, Registered Designation of Origin Saint-Nectaire, and Registered Designation of Origin Salers cheeses, three types of uncooked, semihard, raw milk cheese, were investigated. Coagulase-positive staphylococci (SC+) grew rapidly during the first 6 h. Between 6 and 24 h, counts increased by less than 0.

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Bacteria and yeasts are important sensory factors of raw-milk cheeses as they contribute to the sensory richness and diversity of these products. The diversity and succession of yeast populations in three traditional Registered Designation of Origin (R.D.

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Human feces collected from 10 healthy teenagers was analyzed for the presence of Crenarchaeota. After a first polymerase chain reaction (PCR) with Archaea-specific primers, a nested real-time PCR was performed using Crenarchaeota-specific primers. Real-time Crenarchaeotal PCR products detected from four subjects were cloned and the sequencing revealed that most of the partial 16S rRNA gene sequences were highly similar (> or = 97% homology) to sequences affiliated to the Sulfolobus group of the Crenarchaeota phylum.

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