Scientists at the Institute of Ocean Sciences at the University of Texas at Austin have discovered nearly two dozen new types of microbes, many of which use hydrocarbons such as methane and butane as sources of water. 39 energy to survive and grow, which means that the new bacterium identified could contribute to concentrations of greenhouse gases in the atmosphere and could someday be helpful in cleaning up oil spills.
In an article published in Nature Communications this week, researchers have shown great diversity in the microbial communities living in the extremely hot marine sediments located in the Guaymas Basin in the Gulf of California. The team has discovered new microbial species so genetically different from those previously studied that they represent new branches in the tree of life. Many of these same species possess a devouring power of pollutant, as have other previously identified microbes in the ocean and soil.
"This shows that the depths of the oceans contain unexplored and expansive biodiversity, and that microscopic organisms are capable of degrading oil and other harmful chemicals," said Assistant Professor of Marine Science, Brett Baker. , principal investigator of the document. "Under the ocean floor, there are now huge reservoirs of hydrocarbon gases, including methane, propane, butane and others, and these microbes prevent greenhouse gases from being present. released in the atmosphere. "
The new study, which represents the largest genomic sampling ever conducted for sediments in the Guaymas Basin, was co-written by Nina Dombrowski, a former postdoctoral researcher at UT, and Andreas P. Teske, Professor at the University of North Carolina.
The researchers analyzed 551 genomes, 22 of which represented new entries in the tree of life. They analyzed sediments located 2,000 meters below the surface, where volcanic activity allowed to increase temperatures to around 200 degrees Celsius. According to Baker, these new species were genetically different enough to represent new branches in the tree of life, and some were different enough to represent an entirely new phyla.
"The tree of life is something that people have been trying to understand since Darwin proposed the concept more than 150 years ago, and it's still this moving target right now," said Baker, who was previously part of from a team that has mapped the most comprehensive genomic tree of life to date. "Trying to map the tree is really crucial to understanding all aspects of biology.With DNA sequencing and the computer approaches that we use, we are getting closer and things are growing rapidly."
Only about 0.1% of the world's microbes can be grown, which means that there are still thousands or even millions of microbes to discover.
The Baker team is studying the interactions between microbial communities and the nutrients available in the environment by taking samples of sediments and microbes in the wild and then extracting DNA samples. Researchers are sequencing DNA to reconstruct the individual genomes, the sets of genes in each organism, and deduce from this data how microbes consume different nutrients.
"For this we try to search for organisms that have already been studied and look for similarities and differences," said Dombrowski, currently at the Royal Netherlands Institute of Marine Research. "It may seem easy at first, but it really is not the case, because often more than half of the genes we find are so far unknown and unknown"
The samples were collected using the submarine Alvin, the same submarine as the Titanic, because the microbes live in extreme environments. Teske, who has worked with Baker and Dombrowski, has for several years been leading the collection of samples in the Guaymas Basin, in collaboration with scientists from around the world using different approaches to study life there.
This month, Baker is part of an Alvin sampling team in areas of the basin that had never been studied before.
"We think it's probably only the tip of the iceberg in terms of diversity in the Guaymas Basin," Baker said. "So, we're doing a lot more DNA sequencing to try to figure out how much is left over, this document is really our first clue to what these things are and what they do."
Hemimastigotes represent a major new branch of the evolutionary tree of life
Nina Dombrowski et al., Extensive microbial metabolic versatility and biodiversity in dynamic hydrothermal sediments in the Guaymas Basin, Nature Communications (2018). DOI: 10.1038 / s41467-018-07418-0