800 new bacterial viruses in human intestine mapped

Using a new principle for analysing DNA sequence data, scientists have mapped 500 previously unknown microorganisms and 800 new bacterial viruses in the human intestine.
The 800 previously unknown bacterial viruses (also called bacteriophages) attack intestinal bacteria, said researchers who also identified which bacterial viruses attack which bacteria.
Understanding the intestinal bacteria interactions can help researchers develop a more selective way to treat a number of diseases.
To map the microorganisms, the researchers from Technical University of Denmark Systems Biology developed a new principle for analysing DNA sequence data, which they have named the co-abundance principle.
The principle basically 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.

"Using our method, researchers are now able to identify and collect genomes from previously unknown microorganisms in even highly complex microbial societies. This provides us with an overview we have not enjoyed previously," said Professor Soren Brunak who co-headed the study with Associate Professor Henrik Bjorn Nielsen.

Until now, 200 to 300 intestinal bacterial species had been mapped. Now the number will be more than doubled, which could significantly improve the understanding and treatment of a large number of diseases, researchers said.
The two researchers have 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 Nielsen.

Previously, bacteria were studied individually in the laboratory, but researchers are becoming increasingly aware that in order to understand the intestinal flora, you need to look at the interaction between the many different bacteria found.
"Ideally we will be able to add or remove specific bacteria in the intestinal system and in this way induce a healthier intestinal flora," said Brunak.
The research findings will be published in the journal Nature Biotechnology.