A study entitled “Variability and Potential Causes for Inconsistencies in Human Datasets” was presented by Katherine Pollard, a senior investigator of the Gladstone Institutes at the Obesity and Microbiome symposium of the AAAS Annual Meeting in San Jose, CA on Friday, February 13, 2015.
Appromiately 1,000 different species of bacteria coexist in the human intestine and form the gut microbiota. The total number of genes represented in this highly diverse microbial community is the gut microbiome. Several studies have established a link between the gut microbiome composition and obesity, both in mice and humans.
In recent years, shotgun metagenomics sequencing technology enabled the analysis of genes in complex samples of microbes, such as the gut microbiota. Now, Dr. Pollard and her team developed several new computational methods of analysis for shotgun metagenomes.
By developing a computational shortcut to rapidly estimate genome size using statistical modeling, Dr. Pollard’s team has been able to improve the accuracy of microbiome studies. Using these tools, they reanalyzed several previous published studies and revealed that there is no strong taxonomic signature for obesity in gut micro biomes. In fact, her lab found that there was greater variability in gut bacteria between the different studies than between the lean and obese individuals within each study. They found that functional repertoires of human microbiomes differ more than was previously estimated due to genome variability within bacterial strains (bacterial DNA of two strains vary by 30% while there is only 0.1% of difference between two human genomes).
“It’s not enough to say what type of bacterial species are present, because that doesn’t tell you what they’re doing,” explains Dr. Pollard in a press release by Gladstone Institutes. “Since two strains of the same species can have such different genomes, you really need to know what genes are there and what role they play in order to link someone’s gut microbiota to BMI or disease.”
In other developments in obesity, a team of researchers from Shanghai recently reviewed available evidence concerning a newly-discovered exercise-mediated myokine named Irisin, and its potential role in addressing obesity and other metabolic disorders. The review was recently published in the journal Lipids in Health and Disease.