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World - Tapping the ocean as a source of natural products

Using DNA data, researchers have examined seawater to find not only new species of bacteria, but also previously unknown natural products that may one day prove beneficial.

The oceans are teeming with countless forms of life, from the world's largest creature -- the blue whale -- to miniscule microorganisms. In addition to their vast numbers, these microorganisms are also crucial for ensuring that the entire eco- and climate system work properly. For instance, there are photosynthetically active varieties such as cyanobacteria that produce around 50 percent of the oxygen in the atmosphere. Moreover, by removing carbon dioxide from the atmosphere, microorganisms help counter global warming.

Despite this significant role, research into the diversity of microorganisms found in the ocean has thus far been only rudimentary. So, a group of researchers led by Shinichi Sunagawa, Professor of Microbiome Research, is working closely with Jörn Piel's group to investigate this diversity. Both groups are at the Institute of Microbiology at ETH Zurich.

To detect new natural products made by bacteria, Sunagawa and his team examined publicly available DNA data from 1,000 water samples collected at different depths from every ocean region in the world. The data came from such sources as ocean expeditions and observation platforms positioned out at sea.

Thanks to modern technologies like environmental DNA (eDNA) analysis, it has become easier to search for new species and discover which known organisms can be found where. But what is hardly known at all is what special effects the marine microorganisms offer -- in other words, what chemical compounds they make that are important for interactions between organisms. In the best-case scenario, such compounds would benefit humans as well. Underpinning the research is the assumption that the ocean microbiome harbours great potential for natural products that could prove beneficial, for instance for their antibiotic properties.

The extracted eDNA present in the samples was sequenced by the original researchers of the various expeditions. By reconstructing entire genomes on the computer, the scientists succeeded in decrypting the encoded information -- the blueprints for proteins. Finally, they consolidated this new data together with the existing 8,500 genome data sets for marine microorganisms in a single database.

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