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: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:Mucor species belongs to the Mucorales order within the phylum Mucoromycota, an early diverging fungal lineage. The purpose of this study was to investigate at the transcriptome scale the similarities and differences that could be linked to different lifestyles. Five strains pertaining to five species were studied: M. fuscus and M. lanceolatus, two species used in cheese ripening, M. racemosus, a recurrent cheese spoiler sometimes described as an opportunistic pathogen, M. circinelloides, often described as an opportunistic pathogen and M. endophyticus, a plant endophyte species.
Project description:Lactobacillus helveticus is a rod-shaped lactic acid bacterium that is widely used in the manufacture of fermented dairy foods and for production of bioactive peptides from milk proteins. Although L. helveticus is commonly associated with milk environments, phylogenetic studies show it is closely related to an intestinal species, Lactobacillus acidophilus, which has been shown to impart probiotic health benefits to humans. This relationship has fueled a prevailing hypothesis that L. helveticus is a highly specialized derivative of L. acidophilus which has adapted to acidified whey. However, L. helveticus has also been sporadically recovered from non-dairy environments, which argues the species may not be as highly specialized as is widely believed. This study employed genome sequence analysis and comparative genome hybridizations to investigate genomic diversity among L. helveticus strains collected from cheese, whey, and whiskey malt, as well as commercial cultures used in manufacture of cheese or bioactive dairy foods. Results revealed considerable variability in gene content between some L. helveticus strains, and indicated the species should not be viewed as a strict dairy-niche specialist. In addition, comparative genomic analyses provided new insight on several industrially and ecologically important attributes of L. helveticus that may facilitate commercial strain selection.
Project description:Aside from their amino acid content, dairy proteins are valuable for their ability to carry encrypted bioactive peptides whose activities are latent until released by digestive enzymes or endogenous enzymes within the food. Peptides can possess a wide variety of functionalities, such as antibacterial, antihypertensive, and antioxidative properties, as demonstrated by in vitro and in vivo studies. This phenomenon raises the question as to what impact various traditional cheese-making processes have on the formation of bioactive peptides in the resulting products. In this study, we have profiled the naturally-occurring peptides in two hard and two soft traditional cheeses and have identified their known bioactive sequences. While past studies have typically identified fewer than 100 peptide sequences in a single cheese, we have used modern instrumentation to identify between 2900 and 4700 sequences per cheese, an increase by a factor of about 50. We demonstrated substantial variations in proteolysis and peptide formation between the interior and rind of each cheese, which we ascribed to the differences in microbial composition between these regions. We identified a total of 111 bioactive sequences among the four cheeses, with the greatest number of sequences, 89, originating from Mimolette. The most common bioactivities identified were antimicrobial and inhibition of the angiotensin-converting enzyme. This work revealed that cheese proteolysis and the resulting peptidomes are more complex than originally thought in terms of the number of peptides released, variation in peptidome across sites within a single cheese, and variation in bioactive peptides among cheese-making techniques.
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 M17. At least three independent cultures of the six strains were performed. Genomic DNA was extracted from cells grown overnight on M17 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:Propionibacterium freudenreichii, a dairy starter, reaches a population close to 10^9 propionibacteria per gram of Swiss-type cheese at the time of consumption. Also consumed as a probiotic, it revealed strain-dependent anti-inflammatory properties mediated by proteins inducing IL-10 in leukocytes. Here, strains with varied anti-inflammatory potentials were compared in terms of transcriptome profiles.