Survival and metabolic activity of selected strains ofPropionibacterium freudenreichiiin the gastrointestinal tract of human microbiota-associated rats

Abstract

In addition to their use in cheese technology, dairy propionibacteria have been identified as potential probiotics. However, to have a probiotic effect, propionibacteria have to survive and to remain metabolically active in the digestive tract. The aim of the present study was to investigate the survival and metabolic activity of Propionibacterium freudenreichii within the gastrointestinal tract of human microbiota-associated rats, and its influence on intestinal microbiota composition and metabolism. Twenty-five dairy Propionibacterium strains were screened for their tolerance towards digestive stresses and their ability to produce propionate in a medium mimicking the content of the human colon. Three strains were selected and a daily dose of 2 £ 10 10 colony-forming units was fed to groups of human microbiota-associated rats for 20 d before microbiological, biochemical and molecular investigations being carried out. These strains all reached 8-log values per g faeces, showing their ability to survive in the gastrointestinal tract. Transcriptional activity within the intestine was demonstrated by the presence of P. freudenreichii-specific transcarboxylase mRNA. The probiotic efficacy of propionibacteria was yet species-and strain-dependent. Indeed, two of the strains, namely TL133 and TL1348, altered the faecal microbiota composition, TL133 also increasing the caecal concentration of acetate, propionate and butyrate, while the third strain, TL3, did not have similar effects. Such alterations may have an impact on gut health and will thus be taken into consideration for further in vivo investigations on probiotic potentialities of P. freudenreichii.

Human Microbiota-Secreted Factors Inhibit Shiga Toxin Synthesis by Enterohemorrhagic Escherichia coli O157:H7

“…Seven days later, fecal strict anaerobes, facultative anaerobes, and enterobacteria were numerated to check for colonization. The level of each population was similar to the normal population levels of human feces, indicating successful colonization of the rat digestive tract by the complex human microbiota, as previously described (20). We did not directly inoculate the rats with E. coli O157:H7 because it is known that EHEC colonizes the gut of conventional rodents to a much lesser extent than the guts of germfree or streptomycin-treated rodents (27,28).…”

“…They were given free access to sterile water and a pelleted semisynthetic diet (Scientific Animal Food and Engineering, Augy, France) sterilized by ␥ irradiation at 40 kGy (IBA Mediris, Fleurus, Belgium). To reproduce the diversity of a human-type diet, the food contained lipids and proteins of animal and plant origins, sucrose, and cooked starch (20). Throughout the study, isolators were maintained in controlled conditions of light, temperature, and humidity.…”

Dairy Propionibacteria: Less Conventional Probiotics to Improve the Human and Animal Health

“…Survival of propionibacteria during gastrointestinal transit has also been reported in vivo in rats [125,126]; mice [124,137] and humans [127,130,133]. Furthermore, Herve et al [34], demonstrated that propionibacteria remain metabolically active since the P. freudenreichiispecific transcarboxylase mRNA was detected in human faeces.…”

“…At present, no cases of sickness or toxicity after the ingestion of dairy propionibacteria have been reported [122] neither for humans (for a review of human trials see [123]) nor for animals [124][125][126]. In fact, it has been reported that propionibacteria did not translocate to blood, liver or spleen and no adverse effects on body weight gain and general health status was observed after short [124,127] and long terms [125] administration of strains of Propionibacterium acidipropionici, P. freudenreichii and P. jensenii, respectively.…”

Contribution of Surface β-Glucan Polysaccharide to Physicochemical and Immunomodulatory Properties of Propionibacterium freudenreichii

“…Tolerance toward digestive stresses was shown in vitro to be highly strain dependent in P. freudenreichii strains (36). Compared to their corresponding WT strains, the three KO mutants showed different survival rates under acidic and bile salt stresses, although these differences did not reach significance.…”