In a first, unknown gut bacteria and viruses mapped

Using a new principle for analysing DNA sequence data, researchers have mapped 500 previously unknown micro-organisms in human intestinal flora as well as 800 unknown bacterial viruses which attack intestinal bacteria.

So far, 200-300 intestinal bacterial species have been mapped. Now, the number will be more than doubled, which could significantly improve understanding and treatment of a large number of diseases such as type 2 diabetes, asthma and obesity.

"Using our method, researchers are now able to identify and collect genomes from previously unknown micro-organisms in even highly complex microbial societies. This provides us with an overview we have not enjoyed previously," said professor Soren Brunak from Technical University of Denmark (DTU).

Named "co-abundance principle", the new method assumes that different pieces of DNA from the same organism will occur in the same amount in a sample, and that this amount will vary over a series of samples.

The researchers also studied the mutual relations between bacteria and viruses.

"Our study tells us which bacterial viruses attack which bacteria, something which has a noticeable effect on whether the attacked bacteria will survive in the intestinal system in the long term," said Henrik Bjorn Nielsen, associate professor at DTU.

Knowledge of intestinal bacteria interactions could lead to a more selective way to treat a number of diseases.

"Ideally we will be able to add or remove specific bacteria in the intestinal system and in this way induce a healthier intestinal flora," Brunak added.

The research findings will be published in Nature Biotechnology.