In a comprehensive study that compared the human microbiome from diverse sites, Costello et al. (55) used a multiplexed barcoded pyrosequencing approach to evaluate samples from 27 distinct body sites of selleck bio healthy adults on four occasions. Sampled sites included the oral cavity, gut, and skin surfaces. The V2 region of the 16S rRNA gene was targeted to generate a dataset of about 1 million sequences (average of 1,315 sequences/sample). Overall, the detected taxa comprised representatives of 22 bacterial phyla. Of these, 92% of the sequences belonged to four phyla: Actinobacteria (37%), Firmicutes (34%), Proteobacteria (12%), and Bacteroidetes (9.5%). Each body site was found to harbor a unique microbiota and a group of dominant taxa that remained stable over time. Low-abundance taxa varied significantly.
A high interindividual variability was found within sites. Gut Bacterial diversity in the gut The gut contains the largest number of microorganisms associated with the human body and is regarded as one of the most densely populated microbial ecosystems on this planet (66, 67). In a study by Turnbaugh et al. (68), the pyrosequencing approach was used to evaluate the diversity of bacterial communities in fecal samples from a monozygotic twin pair. Findings were also compared to communities from the gut and other body sites of related and unrelated individuals. The V2 region of the 16S rRNA gene was targeted to generate approximately 1.2�C1.5 million sequencing reads. The total diversity of species-level bacterial phylotypes in the reads obtained from each twin was about 800.
Most species-level phylotypes were present at low abundance. A comparison across 27 body habitats demonstrated high levels of diversity. The combined data from the 27 body sites revealed an estimated 4,949 species-level phylotypes. A study of rural children in Burkina Faso and in Italy analyzed approximately 440,000 sequences from the V5�CV6 regions of the 16S rRNA gene and showed that the Bacteroidetes phylum was far more abundant in microbiomes of African children, with a unique abundance of bacteria from the genus Prevotella and Xylanibacter (69). Most Bacteroidetes representatives detected in the African children are known to have genes for cellulose and xylan hydrolysis, indicating that they are possibly involved in obtaining energy from the plant-rich diet.
Moreover, Enterobacteriaceae taxa were Drug_discovery significantly underrepresented in African children when compared to Italian children. These findings pointed to the fact that microbiomes vary geographically with their hosts, and diet may be one factor involved with such a variation. Gut microbiome in obese individuals Community profiling analysis of the human gut microbiome using cloning and Sanger sequencing disclosed a higher Firmicutes/Bacteroidetes ratio in obese individuals than in lean individuals (70).