Personne :
Roy, Denis

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Université Laval. Faculté des sciences de l'agriculture et de l'alimentation
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Voici les éléments 1 - 6 sur 6
  • Publication
    Accès libre
    Effect of two thermoresistant non-starter lactic acid bacteria strains on volatilome profile during Cheddar ripening simulation
    (Elsevier, 2021-09-03) Roy, Denis; Gagnon, Mérilie; Goulet, Charles; LaPointe, Gisèle; Chouinard, Yvan
    Dairy farm management practices can modify milk microbiota and therefore modulate non-starter lactic acid bacteria (NSLAB) found in cheese. These NSLAB can cause organoleptic defects. This study aimed to investigate the impact of two potential NSLAB in Cheddar cheesemaking: Lactiplantibacillus plantarum RKG 2-212 a strain isolated both in corn silage and raw milk, and Lactobacillus delbrueckii RKG R10, a strain isolated after pas-teurisation of milk from a farm using grass and legume silage, and corn silage. The whole genome of these two lactobacilli was first sequenced. Then, the thermoresistance was evaluated after treatment at 60 ◦C for 5 min and compared to reference strains. Both lactobacilli were highly thermoresistant compared to other three lactic acid bacteria which are Lactococcus lactis subsp. cremoris ATCC 19257 and SK11, and L. plantarum ATCC 14917 (P <0.0001). They lost less than 1 log cfu/mL (Δlog) and their genome contained a great number of copy number of genes coding for heat shock protein. During a Pearce test activity simulating Cheddar cheesemaking, the two lactobacilli did not show interaction with the starter Lcc. lactis subsp. cremoris SK11, and their population remained stable. During a ripening simulation, L. delbrueckii RKG R10 had a slight loss in viability in cheese slurry samples incubated at 30 ◦C for 12 d. However, L. plantarum RKG 2–212 had considerable growth, from 6.51 to 8.3 log cfu/g. This growth was associated with the acidification of the slurries (P <0.0001). The presence of the lactobacilli modified the profile of volatile compounds evaluated by gas chromatography–mass spec-trometry, accounting for 10.7% of the variation. The strain L. plantarum RKG 2-212 produced volatile compounds in greater quantity that could be associated with organoleptic defects such as acetic acid and 2-methylbutyral-dehyde. Therefore, silage can be a vector of thermoresistant lactic acid bacteria for milk which can lead to flavor defects in cheese
  • Publication
    Accès libre
    Raspberry consumption : identification of distinct immune-metabolic response profiles by whole blood transcriptome profiling
    (Elsevier, 2022-01-10) Roy, Denis; Garneau, Véronique; Franck, Maximilien; Toro Martin, Juan de; Couillard, Charles; Varin, Thibaut; Pilon, Geneviève; Vohl, Marie-Claude; Couture, Patrick; Marette, André
    Background. Numerous studies reported that diets rich in phenolic compounds are beneficial to human health, especially for immune-metabolic conditions, yet these effects and underlying mechanisms are not well defined. Objectives. The main goal of this study was to investigate the architecture of the inter-individual variability of the immune-metabolic response to raspberry consumption, by identifying distinct subgroups of participants sharing similar transcriptomic signatures. Methods. The 24 participants assigned to the treated arm of a randomized controlled trial, and at risk of developing metabolic syndrome, received 280g/day of frozen raspberries for 8 weeks. RNAseq data from whole blood assessed at weeks 0 and 8 were used to identify sub-groups of responses to raspberry consumption, by using partial least-squares discriminant analysis (PLS-DA) and hierarchical clustering. Changes in clinical features, metabolic parameters, plasma metabolites and gut metagenomics were compared between the resulting sub-groups. Results. Transcriptomic-based clustering regrouped the initial 24 study participants into two significantly different sub-groups of response to raspberry consumption, with 13 participants being defined as responders and 11 as non-responders. Following raspberry consumption, a significant decrease in plasma triglycerides, total-cholesterol and C-reactive protein was found in the responder sub-group, as compared to the non-responder sub-group. Two major components composed respectively of 100 and 220 genes were further identified by sparse PLS-DA as those better discriminating responders and non-responders. Functional pathways related to cytokine production, leukocyte activation and immune response were significantly enriched with discriminant genes. Factor analysis revealed that the first metabolomic factor mostly composed of decreasing triglycerides and increasing phosphatidylcholines was significantly higher in responders, as compared to non-responders. Analysis of gut metagenomic data revealed differences between responders and non-responders prior to the intervention and distinct modulations, notably regarding Firmicutes and Actinobacteria phyla. Conclusions. The discrimination analysis carried out in the present study based on transcriptional changes following raspberry consumption was able to identify two divergent sub-groups of participants, which were further identified as responders and non-responders, according to their immune-metabolic and gut metagenomic responses. In the context of precision nutrition, this holistic approach represents a promising framework to tackle the issue of inter-individual variability in the understanding of the impact of foods or nutrients on immune-metabolic health.
  • Publication
    Accès libre
    Effects of daily raspberry consumption on immune-metabolic health in subjects at risk of metabolic syndrome : a randomized controlled trial
    (MDPI Pub., 2020-12-17) Roy, Denis; Garneau, Véronique; Franck, Maximilien; Toro Martin, Juan de; Couillard, Charles; Guay, Valérie; Marette, André; Kearney, Michèle; Pilon, Geneviève; Vohl, Marie-Claude; Couture, Patrick; Marette, André
    Consumption of red raspberries has been reported to exert acute beneficial effects on postprandial glycemia, insulinemia, triglyceridemia, and cytokine levels in metabolically disturbed subjects. In a two-arm parallel-group, randomized, controlled trial, 59 subjects with overweight or abdominal obesity and with slight hyperinsulinemia or hypertriglyceridemia were randomized to consume 280 g/day of frozen raspberries or to maintain their usual diet for 8 weeks. Primary analyses measured metabolic differences between the groups. Secondary analyses performed with omics tools in the intervention group assessed blood gene expression and plasma metabolomic changes following the raspberry supplementation. The intervention did not significantly affect plasma insulin, glucose, inflammatory marker concentrations, nor blood pressure. Following the supplementation, 43 genes were differentially expressed, and several functional pathways were enriched, a major portion of which were involved in the regulation of cytotoxicity, immune cell trafficking, protein signal transduction, and interleukin production. In addition, 10 serum metabolites were found significantly altered, among which β-alanine, trimethylamine N-oxide, and bioactive lipids. Although the supplementation had no meaningful metabolic effects, these results highlight the impact of a diet rich in raspberry on the immune function and phospholipid metabolism, thus providing novel insights into potential immune-metabolic pathways influenced by regular raspberry consumption
  • Publication
    Accès libre
    Prevalence and abundance of lactic acid bacteria in raw milk associated with forage types in dairy cow feeding
    (Elsevier Inc., 2020-04-29) Roy, Denis; Groleau, Gisèle.; Gagnon, Mérilie; Chouinard, Yvan; Ouamba, Alexandre J. K.
    Lactic acid bacteria (LAB) found in milk can be responsible for organoleptic defects in cheese. In order to identify the source of LAB thatcouldpotentiallydevelop during cheesemaking, we evaluated theirprevalence and abundanceinmilk according to thetype of forage usedin dairy cow feeding. Foragesand bulk tank milk were sampled three times on 24farms using either hay alone (control), or grass or legume silagesupplemented or not with corn silage. Both types of silageswere either noninoculated, orinoculated with commercial preparations containing at least a Lactobacillus buchneristrainalong with Lactobacillus casei, Lactobacillus plantarum, Enterococcus faecium,or Pediococcus pentosaceus. Our resultsindicate that LAB viable counts in milksamples (2.56log cfu/mL) did not differaccording to the type of forage used. A total of 1239 LAB were isolated and identified by partial 16S rRNA gene sequencing. Although inoculation increased lactobacilli abundance in grass silage by 35%, we did not observe an effect on the LAB profile of milk. Indeed, there was no significant difference in milk LAB prevalence and abundanceaccording tothe type of forage(P >0.05). Moreover, isolates belonging to the L.buchnerigroup wererarely found in bulk tank milk (3/481isolates). Random amplified polymorphic DNA typing of 406LAB isolates revealed theplausibletransfer of some strains from silage to milk (~6%). Thus, forage is only a minor contributor to LAB contamination of milk.
  • Publication
    Accès libre
    Effect of recycled manure solids as bedding on bulk tank milk and implications for cheese microbiological quality
    (American Dairy Science Association, 2019-10-30) Roy, Denis; Gagnon, Mérilie; Fréchette, Annie; Hamelin, Laurie; Dufour, Simon
    The dairy farm environment influences the raw milk microbiota and consequently affects milk processing. Therefore, it is crucial to investigate farm management practices such as the bedding materials. The aim of this study was to evaluate the effect of recycled manure sol-ids (RMS) as bedding material on bulk tank milk and microbiological implications for cheese quality. Bulk tank samples were collected from 84 dairy farms using RMS or straw bedding. The use of RMS did not influ-ence thermophilic and mesophilic aerobic viable counts from spores. However, straw-milk samples gave higher values for mesophilic anaerobic spore-forming bacteria (0.44 log cfu/mL) than RMS-milk samples (0.17 log cfu/mL). The presence of thermoresistant lactic acid bacteria was not increased in milk from farms using RMS. Nevertheless, taxonomic profiles of thermoresis-tant bacteria isolated were different between the 2 types of milk. More Enterococcus faecalis and Streptococcusspp. were identified in RMS-milk samples. Thermore-sistant enterococci and streptococci could easily end up in cheese. Therefore, milk proteolytic activities of these isolates were tested. Neither Streptococcus spp. nor Enterococcus faecium isolates exhibited proteolytic ac-tivities, whereas 53% of E. faecalis showed some. Also, only 1 vancomycin-resistant enterococcus was detected. Survival of selected RMS-milk samples isolates (3 E. faecalis and 1 Streptococcus thermophilus) was evalu-ated during a model Cheddar cheese manufacture. Al-though those strains survived well, they did not modify the acidification curve of milk. However, they might cause organoleptic defects during cheese maturing.
  • Publication
    Accès libre
    Optimization of preservation methods allows deeper insights into changes of raw milk microbiota
    (MDPI AG, 2020-03-05) Roy, Denis; Groleau, Gisèle.; Dufour, Simon; Ouamba, Alexandre J. K.
    The temporal instability of raw milk microbiota drastically affects the reliability of microbiome studies. However, little is known about the microbial integrity in preserved samples. Raw cow milk samples were preserved with azidiol or bronopol and stored at 4 °C, or with dimethyl sulfoxide (DMSO) or a mixture of azidiol and DMSO and stored at −20 °C for up to 30 days. Aliquots of 5-, 10-, and 30-day post-storage were treated with propidium monoazide (PMA), then analyzed by sequencing the 16S rRNA gene V3-V4 and V6-V8 regions. The V6-V8 gave a higher richness and lower diversity than the V3-V4 region. After 5-day storage at 4 °C, the microbiota of unpreserved samples was characterized by a drastic decrease in diversity, and a significant shift in community structure. The treatment with azidiol and DMSO conferred the best community stabilization in preserved raw milk. Interestingly, the azidiol treatment performed as well for up to 10 days, thus appearing as a suitable alternative. However, neither azidiol nor bronopol could minimize fungal proliferation as revealed by PMA-qPCR assays. This study demonstrates the preservative ability of a mixture of azidiol and DMSO and provides deeper insights into the microbial changes occurring during the cold storage of preserved raw milk.