Lactobacillus is the largest genus within the lactic acid bacteria (LAB), with almost 180 species currently identified. Motility has been reported for at least 13 Lactobacillus species, all belonging ...to the Lactobacillus salivarius clade. Motility in lactobacilli is poorly characterized. It probably confers competitive advantages, such as superior nutrient acquisition and niche colonization, but it could also play an important role in innate immune system activation through flagellin–Toll-like receptor 5 (TLR5) interaction. We now report strong evidence of motility in a species outside the L. salivarius clade, Lactobacillus curvatus (strain NRIC0822). The motility of L. curvatus NRIC 0822 was revealed by phase-contrast microscopy and soft-agar motility assays. Strain NRIC 0822 was motile at temperatures between 15 °C and 37 °C, with a range of different carbohydrates, and under varying atmospheric conditions. We sequenced the L. curvatus NRIC 0822 genome, which revealed that the motility genes are organized in a single operon and that the products are very similar (>98.5% amino acid similarity over >11,000 amino acids) to those encoded by the motility operon of Lactobacillus acidipiscis KCTC 13900 (shown for the first time to be motile also). Moreover, the presence of a large number of mobile genetic elements within and flanking the motility operon of L. curvatus suggests recent horizontal transfer between members of two distinct Lactobacillus clades: L. acidipiscis in the L. salivarius clade and L. curvatus inthe L. sakei clade. This study provides novel phenotypic, genetic, and phylogenetic insights into flagellum-mediated motility in lactobacilli.
Immunomodulatory properties of 10 dairy propionibacteria, analyzed on human peripheral blood mononuclear cells (PBMCs), revealed a highly strain-dependent induction of anti-inflammatory cytokine ...interleukin 10 (IL-10). Two selected strains of Propionibacterium freudenreichii showed a protective effect against two models of colitis in mice, suggesting a probiotic potential predicted by immune-based selection criteria for these cheese starter bacteria.
is a beneficial bacterium, used as a cheese starter, which presents versatile probiotic properties. These properties are strain-dependent. We hypothesized they may also be delivery vehicle-dependent. ...In this study, we thus explored in healthy piglets how the cheese matrix affects the immunomodulatory properties of
. During 2 weeks, three groups of weaned piglets consumed, respectively,
as a liquid culture (PF-culture),
under the form of a cheese (PF-cheese), or a control sterile cheese matrix (Cheese-matrix). The
metabolic activity of
was assessed by determining short chain fatty acids (SCFA) concentration and bifidobacteria population in feces. Whatever the delivery vehicle,
was metabolically active in piglets' colon and enhanced both bifidobacteria and SCFA in feces.
consumption decreased the secretion of TNFα and of IL-10 by peripheral blood mononuclear cells (PBMC). It did not alter IL-10, IFNγ, IL-17, and TNFα secretion in mesenteric lymph node immune cells (MLNC). PF-cheese enhanced significantly Treg phenotype, while PF-culture decreased significantly Th17 phenotype in PBMC and MLNC. Remarkably, only PF-cheese induced an increase of Th2 phenotype in PBMC and MLNC.
stimulation of PBMC and MLNC by Lipopolysaccharides and Concanavalin A emphasized the difference in the immunomodulatory responses between PF-culture and PF-cheese group, as well as between PBMC and MLNC. This study shows the importance to consider the delivery vehicle for probiotic administration. It confirms the anti-inflammatory potential of
. It opens new perspectives for the use propionibacteria-fermented products as preventive agents for inflammatory bowel diseases and intestinal infectious diseases.
TNF-Related Apoptosis-Inducing Ligand (TRAIL) is a well-known apoptosis inducer, which activates the extrinsic death pathway. TRAIL is pro-apoptotic on colon cancer cells, while not cytotoxic towards ...normal healthy cells. However, its clinical use is limited by cell resistance to cell death which occurs in approximately 50% of cancer cells. Short Chain Fatty Acids (SCFA) are also known to specifically induce apoptosis of cancer cells. In accordance, we have shown that food grade dairy propionibacteria induce intrinsic apoptosis of colon cancer cells, via the production and release of SCFA (propionate and acetate) acting on mitochondria. Here, we investigated possible synergistic effect between Propionibacterium freudenreichii and TRAIL. Indeed, we hypothesized that acting on both extrinsic and intrinsic death pathways may exert a synergistic pro-apoptotic effect. Whole transcriptomic analysis demonstrated that propionibacterial supernatant or propionibacterial metabolites (propionate and acetate), in combination with TRAIL, increased pro-apoptotic gene expression (TRAIL-R2/DR5) and decreased anti-apoptotic gene expression (FLIP, XIAP) in HT29 human colon cancer cells. The revealed synergistic pro-apoptotic effect, depending on both death receptors (TRAIL-R1/DR4, TRAIL-R2/DR5) and caspases (caspase-8, -9 and -3) activation, was lethal on cancer cells but not on normal human intestinal epithelial cells (HIEC), and was inhibited by Bcl-2 expression. Finally, milk fermented by P. freudenreichii induced HT29 cells apoptosis and enhanced TRAIL cytotoxic activity, as did P. freudenreichii DMEM culture supernatants or its SCFA metabolites. These results open new perspectives for food grade P. freudenreichii-containing products in order to potentiate TRAIL-based cancer therapy in colorectal cancer.
Dairy propionibacteria, including Propionibacterium freudenreichii, display promising probiotic properties, including immunomodulation. These properties are highly strain-dependent and rarely studied ...in a fermented dairy product. We screened 10 strains, grown in a newly developed fermented milk ultrafiltrate, for immunomodulatory properties in vitro. The most anti-inflammatory strain, P. freudenreichii BIA129, was further tested on piglets. P. freudenreichii-fermented product improved food intake and growth of piglets. Colonic mucosa explants of treated pigs secreted less interleukin 8 (−25%, P < 0.05) and tumor necrosis factor α (−20%, P < 0.05), either in basal conditions or after a lipopolysaccharide challenge. By contrast, the gut structure, barrier function (measured ex vivo in Ussing chambers), microbial diversity (assessed by 16S rRNA pyrosequencing), and colonic short-chain fatty acid content were unchanged, assuming maintenance of normal intestinal physiology. In conclusion, this work confirms in vivo probiotic properties of dairy propionibacteria-fermented products, which are promising for the prevention or healing of inflammatory bowel diseases.
Probiotics have been the subject of intensive research, mainly focusing on bifidobacteria and lactic acid bacteria. However, there is evidence that dairy propionibacteria also display probiotic ...properties, which as yet have been underestimated. The aim of this paper is to review recent data which report probiotic characteristics of dairy propionibacteria and to distinctly organise them based on the experimental strategy employed: ranked from in vitro evidence to in vivo trials, which is a new approach. In addition to the selection criteria for probiotics in areas such as food safety, technological and digestive stress tolerance, many potential health benefits have been described which include modulation of microbiota andmetabolic activity in the gut, modulation of intestinal motility and absorption, impact on intestinal inflammation, modulation of the immune system and potential modulation of risk factors for cancer development. The robust nature of dairy propionibacteria towards technological stresses should allow their future use in various fermented probiotic foods. Among the probiotic properties of dairy propionibacteria described in the literature, some of these properties are different from those reported for bifidobacteria and lactic acid bacteria. However, supplementation with dairy propionibacteria in randomised, placebo-controlled, double-blind human trials has mainly involved mixtures of propionibacteria with probiotic bacteria from other genera. Clinical studies involving the use of dairy propionibacteria alone are lacking. Such studies will allow the specifically observed health benefits to be attributed to dairy propionibacteria. This, in turn, will allow the investigation of the synergistic effects with other probiotic bacteria or beneficial food components.
Dairy propionibacteria display probiotic properties which require high populations of live and metabolically active propionibacteria in the colon. In this context, the probiotic vector determines ...probiotic efficiency. Fermented dairy products protect propionibacteria against digestive stresses and generally contain a complex mixture of lactic and propionic acid bacteria. This does not allow the identification of dairy propionibacteria specific beneficial effects. The aim of this study was to develop a dairy product exclusively fermented by dairy propionibacteria. As they grow poorly in milk, we determined their nutritional requirements concerning carbon and nitrogen by supplementing milk ultrafiltrate (UF) with different concentrations of lactate and casein hydrolysate. Milk or UF supplemented with 50 mM lactate and 5 g L−1 casein hydrolysate allowed growth of all dairy propionibacteria studied. In these new fermented dairy products, dairy propionibacteria remained viable and stress-tolerant in vitro during minimum 15 days at 4 °C. The efficiency of milk fermented by the most tolerant Propionibacterium freudenreichii strain was evaluated in piglets. Viability and SCFA content in the colon evidenced survival and metabolic activity of P. freudenreichii. This work results in the design of a new food grade vector, which will allow preclinical and clinical trials.
► We developed the first fermented milk exclusively fermented by a dairy propionibacterium. ► Dairy propionibacteria remained viable during storage at 4 °C in this new fermented milk. ► Dairy propionibacteria survived to digestive stress in this new fermented milk. ► This new fermented milk allowed high level and metabolically active propionibacteria population in vivo.
, found in the intestinal microbiota of humans and animals, is studied as an example of the sub-dominant intestinal commensals that may impart benefits upon their host. Strains typically harbour at ...least one megaplasmid that encodes functions contributing to contingency metabolism and environmental adaptation. RNA sequencing (RNA-seq)transcriptomic analysis of
strain UCC118 identified the presence of a novel unusually abundant long non-coding RNA (lncRNA) encoded by the megaplasmid, and which represented more than 75 % of the total RNA-seq reads after depletion of rRNA species. The expression level of this 520 nt lncRNA in
UCC118 exceeded that of the 16S rRNA, it accumulated during growth, was very stable over time and was also expressed during intestinal transit in a mouse. This lncRNA sequence is specific to the
species; however, among 45
genomes analysed, not all (only 34) harboured the sequence for the lncRNA. This lncRNA was produced in 27 tested
strains, but at strain-specific expression levels. High-level lncRNA expression correlated with high megaplasmid copy number. Transcriptome analysis of a deletion mutant lacking this lncRNA identified altered expression levels of genes in a number of pathways, but a definitive function of this new lncRNA was not identified. This lncRNA presents distinctive and unique properties, and suggests potential basic and applied scientific developments of this phenomenon.
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