The Firmicutes/Bacteroidetes ratio of the human microbiota changes with age

<p>Abstract</p> <p>Background</p> <p>In humans, the intestinal microbiota plays an important role in the maintenance of host health by providing energy, nutrients, and immunological protection. Applying current molecular methods is necessary to surmount the limitations of classical culturing techniques in order to obtain an accurate description of the microbiota composition.</p> <p>Results</p> <p>Here we report on the comparative assessment of human fecal microbiota from three age-groups: infants, adults and the elderly. We demonstrate that the human intestinal microbiota undergoes maturation from birth to adulthood and is further altered with ageing. The counts of major bacterial groups <it>Clostridium leptum, Clostridium coccoides</it>, <it>Bacteroidetes, Bifidobacterium, Lactobacillus </it>and <it>Escherichia coli </it>were assessed by quantitative PCR (qPCR). By comparing species diversity profiles, we observed age-related changes in the human fecal microbiota. The microbiota of infants was generally characterized by low levels of total bacteria. <it>C. leptum </it>and <it>C. coccoides </it>species were highly represented in the microbiota of infants, while elderly subjects exhibited high levels of <it>E. coli </it>and <it>Bacteroidetes</it>. We observed that the ratio of <it>Firmicutes </it>to <it>Bacteroidetes </it>evolves during different life stages. For infants, adults and elderly individuals we measured ratios of 0.4, 10.9 and 0.6, respectively.</p> <p>Conclusion</p> <p>In this work we have confirmed that qPCR is a powerful technique in studying the diverse and complex fecal microbiota. Our work demonstrates that the fecal microbiota composition evolves throughout life, from early childhood to old age.</p

EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA); Scientific Opinion on the substantiation of health claims related to a combination of Lactobacillus helveticus CNCM I-1722 and Bifidobacterium longum subsp. Longum CNCM I-3470 and alleviation of psychological stress (ID 938) and “maintains the balance of healthy microbiota that helps to strengthen the natural defence” (ID 2942) (further assessment) pursuant to Article 13(1) of Regulation (EC) No 1924/2006

&lt;p&gt;Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to provide a scientific opinion on health claims pursuant to Article 13 of Regulation (EC) No 1924/2006 in the framework of further assessment related to a combination of &lt;em&gt;Lactobacillus &lt;/em&gt;&lt;em&gt;helveticus&lt;/em&gt; CNCM I-1722 and &lt;em&gt;Bifidobacterium longum&lt;/em&gt; subsp. &lt;em&gt;longum &lt;/em&gt;CNCM I-3470 and alleviation of psychological stress and “maintains the balance of healthy microbiota that helps to strengthen the natural defence”. The food constituent that is the subject of the health claims, a combination of &lt;em&gt;L. helveticus&lt;/em&gt; CNCM I-1722 and &lt;em&gt;B. longum&lt;/em&gt; subsp. &lt;em&gt;longum &lt;/em&gt;CNCM I-3470, is sufficiently characterised. The claimed effect, alleviation of psychological stress, is a beneficial physiological effect. No human intervention studies were provided from which conclusions could be drawn for the scientific substantiation of the claim. On the basis of the data provided, the Panel concludes that a cause and effect relationship has not been established between the consumption of a combination of &lt;em&gt;L. helveticus&lt;/em&gt; CNCM I-1722 and &lt;em&gt;B. longum&lt;/em&gt; subsp. &lt;em&gt;longum &lt;/em&gt;CNCM I-3470 and alleviation of psychological stress. From the information provided for the claimed effect “maintains the balance of healthy microbiota that helps to strengthen the natural defence” it was not possible to establish the specific effect which is the subject of the claim. The Panel considers that the claimed effect is general and non-specific, and does not refer to any specific health claim as required by Regulation (EC) No 1924/2006.&lt;/p&gt

A bacteriophage detection tool for viability assessment of Salmonella cells

Available online 7 September 2013Salmonellosis, one of the most common food and water-borne diseases, has a major global health and economic impact. Salmonella cells present high infection rates, persistence over inauspicious conditions and the potential to preserve virulence in dormant states when cells are viable but non-culturable (VBNC). These facts are challenging for current detection methods. Culture methods lack the capacity to detect VBNC cells, while biomolecular methods (e.g. DNA- or protein-based) hardly distinguish between dead innocuous cells and their viable lethal counterparts. This work presents and validates a novel bacteriophage (phage)-based microbial detection tool to detect and assess Salmonella viability. Salmonella Enteritidis cells in a VBNC physiological state were evaluated by cell culture, flow-cytometry and epifluorescence microscopy, and further assayed with a biosensor platform. Free PVP-SE1 phages in solution showed the ability to recognize VBNC cells, with no lysis induction, in contrast to the minor recognition of heat-killed cells. This ability was confirmed for immobilized phages on gold surfaces, where the phage detection signal follows the same trend of the concentration of viable plus VBNC cells in the sample. The phage probe was then tested in a magnetoresistive biosensor platform allowing the quantitative detection and discrimination of viable and VBNC cells from dead cells, with high sensitivity. Signals arising from 3 to 4 cells per sensor were recorded. In comparison to a polyclonal antibody that does not distinguish viable from dead cells, the phage selectivity in cell recognition minimizes false-negative and false-positive results often associated with most detection methods

Intestinal microbiota in human health and disease: the impact of probiotics

The complex communities of microorganisms that colonise the human gastrointestinal tract play an important role in human health. The development of culture-independent molecular techniques has provided new insights in the composition and diversity of the intestinal microbiota. Here, we summarise the present state of the art on the intestinal microbiota with specific attention for the application of high-throughput functional microbiomic approaches to determine the contribution of the intestinal microbiota to human health. Moreover, we review the association between dysbiosis of the microbiota and both intestinal and extra-intestinal diseases. Finally, we discuss the potential of probiotic microorganism to modulate the intestinal microbiota and thereby contribute to health and well-being. The effects of probiotic consumption on the intestinal microbiota are addressed, as well as the development of tailor-made probiotics designed for specific aberrations that are associated with microbial dysbiosis

Etudes chez l'homme de la survie de souches 'probiotiques' en transit dans le tractus gastro-intestinal et influence de leur consommation sur l'homéostasie du microbiote

Les bactéries composant le microbiote intestinal jouent un rôle important dans le maintien et l'amélioration de la santé humaine. Dans ce contexte, nous nous sommes intéressés au devenir de souches probiotiques en regardant leurs aptitudes à survivre à leur passage à travers le tractus digestif de l homme, et à étudier leur influence sur l équilibre du microbiote intestinal. Nous avons développé et validé la PCR quantitative en temps réel en dessinant des sondes et des amorces spécifiques des souches probiotiques étudiées et des groupes phylogénétiques dominants et sous-dominants du microbiote intestinal humain. Nous n avons démontré aucun effet de la consommation des souches probiotiques sur l'homéostasie du microbiote pour les populations fécales dominantes. En revanche, des modifications ont été observées sur le microbiote sous-dominant, et plus particulièrement la population d entérocoques qui a été augmenté de manière significative sous l effet de la prise de Camembert.The bacterial inhabitants of the human digestive tract, i.e. the intestinal microbiota, play an important role in the maintenance and the improvement of health. In this context, we are interested in the fate of probiotic strains by studying their aptitudes to survive during their passage through the human digestive tract, and their influence on the balance of the intestinal microbiota. We have developed and validated the real-time quantitative PCR by designing specific probes and primers targeting the studied probiotic strains and the dominant and sub-dominant phylogenetic groups of the human intestinal microbiota. We did not observe any effect of the consumption of probiotic strains on the microbiota homeostasis for the dominant faecal populations. However, modulations were observed on the sub-dominant microbiota, especially the population of enterococci which has been significantly increased as a result of Camembert cheese consumption.CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF

Identification of Genetic Markers for the Detection of <i>Bacillus thuringiensis</i> Strains of Interest for Food Safety

Bacillus thuringiensis (Bt), belonging to the Bacillus cereus (Bc) group, is commonly used as a biopesticide worldwide due to its ability to produce insecticidal crystals during sporulation. The use of Bt, especially subspecies aizawai and kurstaki, to control pests such as Lepidoptera, generally involves spraying mixtures containing spores and crystals on crops intended for human consumption. Recent studies have suggested that the consumption of commercial Bt strains may be responsible for foodborne outbreaks (FBOs). However, its genetic proximity to Bc strains has hindered the development of routine tests to discriminate Bt from other Bc, especially Bacillus cereus sensu stricto (Bc ss), well known for its involvement in FBOs. Here, to develop tools for the detection and the discrimination of Bt in food, we carried out a genome-wide association study (GWAS) on 286 complete genomes of Bc group strains to identify and validate in silico new molecular markers specific to different Bt subtypes. The analyses led to the determination and the in silico validation of 128 molecular markers specific to Bt, its subspecies aizawai, kurstaki and four previously described proximity clusters associated with these subspecies. We developed a command line tool based on a 14-marker workflow, to carry out a computational search for Bt-related markers from a putative Bc genome, thereby facilitating the detection of Bt of interest for food safety, especially in the context of FBOs

Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus survive gastrointestinal transit of healthy volunteers consuming yogurt

International audienceTo date, there is significant controversy as to the survival of yogurt bacteria (namely, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) after passage through the human gastrointestinal tract. Survival of both bacterial species in human feces was investigated by culture on selective media. Out of 39 samples recovered from 13 healthy subjects over a 12-day period of fresh yogurt intake, 32 and 37 samples contained viable S. thermophilus (median value of 6.3 x 10(4) CFU g(-1) of feces) and L. delbrueckii (median value of 7.2 x 10(4)CFU g(-1) of feces), respectively. The results of the present study indicate that substantial numbers of yogurt bacteria can survive human gastrointestinal transit

Genomic insight to understand the persistence of Listeria monocytogenes strains in processing environments of pork products

Listeria monocytogenes (L. monocytogenes) is an ubiquitous bacterium that causes a severe foodborne illness. It is established that the contamination of food production facilities over long time period, are potentially one of the major food product contamination sources. L. monocytogenes persistence was observed in almost all food sectors and particularly in pork production facilities. The characterization of such L. monocytogenes contamination is therefore crucial to improve the food safety and prevent outbreaks. These strains are called persistent but this trait remains loosely defined, and no genetic determinants have been firmly associated with it. This study aims at identifying molecular markers associated with the persistence. A panel of 13 presumed persistent (PP) strains, versus 9 strains not exposed to food processing environment (NEP) strains, was constructed from the databases of the French Institute for Pig and Pork Industry (Ifip), the French National Reference Laboratory (NRL) and the European Union Reference Laboratory (EURL), the last two are hosted by Anses. The genome sequences obtained in the present study were compared to 180 genomes of the Anses strains reference collection and 340 genomes publicly available. Two analysis were performed on the genomes, (i) an allele diversity analysis of 14 loci gathered from a review of significant functions potentially involved in the persistence capacity and (ii) a whole genome variant calling analysis to detect single nucleotide polymorphisms (SNPs) and insertions, deletions specific of persistent strains. The preliminary results were obtained on 4 strains. The comparison of these whole genome sequencing (WGS) data with those of the whole strain panel is ongoing.</p

Management of Listeria monocytogenes on Surfaces via Relative Air Humidity: Key Role of Cell Envelope

International audienceAlthough relative air humidity (RH) strongly influences microbial survival, its use for fighting surface pathogens in the food industry has been inadequately considered. We asked whether RH control could destroy Listeria monocytogenes EGDe by envelope damage. The impact of dehydration in phosphate-buffered saline (PBS) at 75%, 68%, 43% and 11% RH on the bacterial envelope was investigated using flow cytometry and atomic force microscopy. Changes after rehydration in the protein secondary structure and peptidoglycan were investigated by infrared spectroscopy. Complementary cultivability measurements were performed by running dehydration–rehydration with combinations of NaCl (3–0.01%), distilled water, city water and PBS. The main results show that cell membrane permeability and cell envelope were greatly altered during dehydration in PBS at 68% RH followed by rapid rehydration. This damage led cells to recover only 67% of their initial volume after rehydration. Moreover, the most efficient way to destroy cells was dehydration and rehydration in city water. Our study indicates that rehydration of dried, sullied foods on surfaces may improve current cleaning procedures in the food industry