Scientists at the University of Texas at the Institute of Marine Sciences in Austin discovered nearly two dozen new types of microbes, many of which use hydrocarbons such as methane and butane as energy sources to survive and grow, which means that newly identified bacteria could help limit concentrations of greenhouse gases in the atmosphere and someday could be useful to clean up oil spills.
In an article published in Communications of nature This week, the researchers documented a wide diversity in the microbial communities that live in the extremely hot deep-sea sediments located in the Guaymas Basin in the Gulf of California. The team discovered new microbial species that are so genetically different from those previously studied that they represent new branches in the tree of life. Many of these same species possess acute powers to eat contaminants, like other previously identified microbes in the ocean and soil.
"This shows that deep oceans contain a great unexplored biodiversity and that microscopic organisms can degrade oil and other harmful chemicals," said assistant professor of marine sciences Brett Baker, the principal investigator of the article. "Beneath 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 released into the atmosphere."
The new study, which represents the largest genomic sampling of sediments in the Guaymas basin, was co-authored by former UT postdoctoral researcher Nina Dombrowski and North Carolina University professor Andreas P. Teske.
The researchers' analysis of sediments 2,000 meters below the surface, where volcanic activity raises temperatures to around 200 degrees Celsius, recovered 551 genomes, 22 of which represented new entries in the tree of life. 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 completely new phyla.
"The tree of life is something that people have been trying to understand since Darwin came up with the concept more than 150 years ago, and this goal is still moving at the moment," said Baker, who was previously part of a team. that mapped the most complete 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 we use, we are getting closer and things are expanding rapidly."
Only about 0.1 percent of the world's microbes can be grown, which means there are thousands, maybe even millions, of microbes yet to be discovered.
Baker's team investigates the interactions between microbial communities and the nutrients available to them in the environment by taking samples of sediments and microbes from nature and then extracting DNA from the samples. The researchers sequence the DNA to join the individual genomes, the sets of genes in each organism, and deduce from the data how the microbes consume different nutrients.
"For this, we try to look for organisms that have been studied before and look for similarities and differences," said Dombrowski, who is now at the Royal Netherlands Institute for Marine Research. "This may initially seem easy, but in reality it does not it is, since often more than half of the genes we find are not characterized and are unknown until now. "
The samples were collected using the submersible Alvin, the same submarine that found the Titanic, because the microbes live in extreme environments. Teske, who collaborated with Baker and Dombrowski, has encouraged the collection of samples in the Guaymas Basin for several years, working with scientists from around the world who use different approaches to study life there.
This month, Baker is part of a team in Alvin's sampling in areas of the basin that had never been studied before.
"We believe that this is probably the tip of the iceberg in terms of diversity in the Guaymas Basin," Baker said. "So, we are doing a lot more DNA sequences to try to know how much more there is, this document is really our first indication of what these things are and what they are doing."
It was found that hemimastigotes represent a new important branch in the evolutionary tree of life
Nina Dombrowski et al, expansive microbial metabolic versatility and biodiversity in dynamic hydrothermal sediments of the Guaymas Basin, Communications of nature (2018). DOI: 10.1038 / s41467-018-07418-0