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

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

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