Project description:The cheese microbial community is dense with relatively low complexity and composed of cultivable prokaryotic and eukaryotic microorganisms. The ripening process can thus be reproduced under controlled conditions. A reduced microbial community composed of yeasts and bacteria was assembled to mimic that of smear-ripened cheese. The genomes of the microorganisms have been sequenced and annotated, which allows access to gene expression under various conditions at different ripening times. Through the use of a combined approach using omics (e.g. metatranscriptomics, volatilomics), and biochemical/microbial analyses, we have investigated the effect of a biotic perturbation, omission of some yeast, on the stability and functionality of the microbial cheese community throughout ripening.
Project description:Investigation of the interactions between Brevibacterium aurantiacum strains and Hafnia alvei in a lab scale mini-cheese model using high-throughput RNA sequencing
Project description:The intra sub-species diversity of six strains of Lactococcus lactis subsp. lactis was investigated at the genomic level and in terms of phenotypic and transcriptomic profiles in UF-cheese model. Six strains were isolated from various sources, but all are exhibiting a dairy phenotype. Our results showed that, the six strains exhibited small phenotypic differences since similar behaviour in terms of growth was obtained during cheese ripening while only different acidification capability was detected. Even if all strains displayed high genomic similarities, sharing a high core genome of almost two thousands genes, the expression of this core genome directly in the cheese matrix revealed major strain-specific differences. This strains with the same dairy origin. Strains were cultured on skimmed raw milk ultrafiltration (UF) retentate. The UF retentate was pre-incubated overnight at 4 °C, then 45 minutes at 50 °C and homogenized during 1.5 minutes at 24 000 rpm with an ultra-turax (Imlab, France). After addition of rennet (0.3 µl ml-1), 400 g UF retentate was inoculated at 2 106 CFU/g with L. lactis subsp. lactis strains. After incubation for 8 hours at 30 °C, the cheeses were transferred at 12° C until 7 days for ripening simulation. At least three independent cultures of the six strains were performed. Total RNA was extracted from cells grown 24 hours in UF-cheese and radiolabelled cDNA were prepared and hybridized on nylon arrays. 1948 amplicons specific of Lactococcus lactis IL1403 genes were spotted twice on the array. 3 independent repetitions were performed.
Project description:The intra sub-species diversity of six strains of Lactococcus lactis subsp. lactis was investigated at the genomic level and in terms of phenotypic and transcriptomic profiles in UF-cheese model. Six strains were isolated from various sources, but all are exhibiting a dairy phenotype. Our results showed that, the six strains exhibited small phenotypic differences since similar behaviour in terms of growth was obtained during cheese ripening while only different acidification capability was detected. Even if all strains displayed high genomic similarities, sharing a high core genome of almost two thousands genes, the expression of this core genome directly in the cheese matrix revealed major strain-specific differences. This strains with the same dairy origin.
Project description:RNA-seq was used in combination with various analytical chemistry approaches to identify the chemical and genetic basis of pigment production of the bacterium Glutamicibacter arilaitensis when growing on cheese. This bacterium commonly found in cheese rinds where it co-occurs with Penicillium species and other molds. Pinkish-red pigments are produced by the bacterium in response to growth with Penicillium. Both chemical analyses and RNA-seq point to coproporphyrin III as the major metabolite leading to pigment formation.
Project description:The goal of this project was to use a randomized, cross over design to determine the amino acid blood and muscle response to the acute ingestion of cheddar cheese in comparison to that of bovine milk and to investigate the skeletal muscle mTORC1 response.
Project description:Effect of the presence of Lactococcus lactis on Staphylococcus aureus transcriptome in cheese matrix. S. aureus was co-cultured with L. lactis LD61 in cheese matrix during 7 days. RNA samples were extracted at different time points (6 h, 8 h, 10 h, 24 h and 7 days) in order to monitor the dynamic response of S. aureus MW2 in cheese matrix in presence of L. lactis