A gene catalogue of the human gut microbiome
An international group of researchers has established a catalogue of the human gut microbiome. The human digestive system housed millions of bacteria which are important for a healthy life. However, the modern World faces problems like obesity and it is important to understand processes happening in microbes in patients.
The group has investigated microbial genes in the materials taken from 124 individuals of Nordic and Mediterranean origin suffering from overweight and obese, as well as inflammatory bowel disease (IBD). They aimed to cover prevalent intestinalmicrobial genes and in the end the 3.3 million microbial (.86% of prevalent genes in their cohort) genes have been included in the catalogue contains, what is 150-fold more than the human gene complement.
It can be predicted that we share gens, but the result of this research were one more proof/ Here individuals largely share the genes of the common pool. At the present depth of sequencing, we found that almost 40%of the genes fromeach individual are shared with at least half of the individuals of the cohort. Future studies of world-wide span, envisaged within the International Human Microbiome Consortium, will complete, as necessary, our gene catalogue and establish boundaries to the proportion of shared genes. Essentially all (99.1%) of the genes of our catalogue are of bacterial origin, the remainder beingmostly archaeal, with only 0.1%of eukar- yotic and viral origins. The gene catalogue is therefore equivalent to that of some 1,000 bacterial species with an average-sized genome, encoding about 3,364 non-redundant genes. We estimate that no more than 15% of prevalent genes of our cohort may be missing from the catalogue, and suggest that the cohort harbours no more than,1,150 bacterial species abundant enough to be detected by our sampling. Given the large overlap between microbial sequences in this and previous studies we suggest that the number of abundant intestinal bacterial species may be not much higher than that observed in our cohort. Each individual of our cohort harbours at least 160 such bacterial species, as estimated by the average prevalent gene number, and many must thus be shared. We assigned about 12% of the reference set genes (404,000) to the 194 sequenced intestinal bacterial genomes, and can thus associate them with bacterial species. Sequencing of at least 1,000 human- associated bacterial genomes is foreseen within the International Human Microbiome Consortium, via the Human Microbiome Project and MetaHIT. This is commensurate with the number of dominant species in our cohort and expectedmore broadly in human gut, and should enable amuchmore extensive gene to species assign- ment. Nevertheless, we used the presently available sequenced genomes to explore further the concept of largely shared species among our cohort and identified 75 species common to .50% of individuals and 57 species common to .90%. These numbers are likely to increase with the number of sequenced reference strains and a deeper sampling. Indeed, a 2–3-fold increase in sequencing depth raised by 25% the number of species that we could detect as shared between two individuals. A large number of shared species supports the view that the prevalent human microbiome is of a finite and not overly large size. How can this view be reconciled with that of a con Your summary should address the following questions:
This was made possible by using the modern techniques for DNA determination and
This result is important not only as they forms a gen library, but proofs an idea of principle possibility to use short-read sequencing to characterize complex microbiomes, without sampling the full bacterial gene complement of each individual. Figure 1 shows that the coverage done by the presented experiment set was inn the line with the literature data. This makes possible further excavation for other ethnic groups with a better resource and time planning without loosing the information.
