Study Title:

The Gut Microbial Gene Frontier

Study Abstract

To understand the impact of gut microbes on human health and well-being it is crucial to assess their genetic potential. Here we describe the Illumina-based metagenomic sequencing, assembly and characterization of 3.3 million non-redundant microbial genes, derived from 576.7 gigabases of sequence, from faecal samples of 124 European individuals. The gene set, ~150 times larger than the human gene complement, contains an overwhelming majority of the prevalent (more frequent) microbial genes of the cohort and probably includes a large proportion of the prevalent human intestinal microbial genes. The genes are largely shared among individuals of the cohort. Over 99% of the genes are bacterial, indicating that the entire cohort harbours between 1,000 and 1,150 prevalent bacterial species and each individual at least 160 such species, which are also largely shared. We define and describe the minimal gut metagenome and the minimal gut bacterial genome in terms of functions present in all individuals and most bacteria, respectively.

From press release:

Some of the hundreds of bacteria found in the digestive systems of humans may be linked to specific diseases like cancer, diabetes and obesity, an international team of scientists said in a paper on Thursday.

Researchers, led by Chinese scientist Wang Jun, said in the latest issue of Nature they found more than 1,000 different species of bacteria in the human gut.

They said they had sequenced, or analyzed, the genes of each bacteria, creating the first genetic catalog of the organisms found in the human digestive system. Their research was based on analysis of stool samples from 124 people from Denmark and Spain.

Wang and his fellow researchers found several genes that may be linked to obesity and Crohn's disease, but he said more validation work was needed.

"Apart from helping you digest, these bacteria may also play a very important role in ... diseases like Crohn's disease, cancer, obesity," Wang, executive director of the Beijing Genomics Institute, said in an interview with Reuters.

"If you just tackle these bacteria, it is easier than treating the human body itself. If you find that a certain bug is responsible for a certain disease and you kill it, then you kill the disease," Wang said.

Crohn's disease is an inflammatory illness of the intestines which some believe may be caused by a variety of bacteria. Other possible causes include genetics and environmental factors.

Wang said creating the genetic catalog of all the bacteria in the human gut was only a beginning.

"There are a lot of unknown bacteria and pathogens that can cause different kinds of diseases," he said.

"So this is the first step and we have to study further to find concrete associations between these bacteria and human diseases, and then you can start learning how to get diagnosis, prognosis and then treatment," Wang said.

Wang and colleagues in China are working on a similar 120-sample study in Chinese hospitals.

"There are four groups: obese diabetics, obese non-diabetics, lean diabetics and lean non-diabetics. And we found some interesting bugs related to each type of diabetes," Wang said.

Study Information

Jun Wang, et al.
A human gut microbial gene catalogue established by metagenomic sequencing
Nature
2010 March
BGI-Shenzhen, Shenzhen 518083, China.

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