Genomes from uncultivated bacteria offers clues to ancestral bacteria’s energy sources.
Samples of Margulisbacteria were collected at a number of locations, including Rifle, Colo., (left) and from the Gulf of Maine off the coast of Boothbay Harbor, Maine (right). (Image of Rifle, Colo. sampling site by Roy Kaltschmidt, Berkeley Lab. Image of sunset over the Gulf of Maine by NASA/SABOR/Wayne Slade, Sequoia Scientific, Flickr CC BY 2.0)
More than two billion years ago, cyanobacteria acquired the ability to produce their own food and generate oxygen as a byproduct. The abundance of oxygen shaped the evolution of life on Earth, and led to the development of multicellular organisms.
Not all bacterial lineages harnessed aerobic respiration when the Cyanobacteria did; contemporaries Melainabacteria and Sericytochromatia, members of the same clade as Cyanobacteria, applied strategies other than photosynthesis to gain and harness energy.
As reported January 28, 2019 in Nature Communications, two research teams joined forces and data sets to describe bacterial genomes for related (“sibling”) lineages Margulisbacteria and Saganbacteria that diverged from the bacterial tree before Cyanobacteria and its contemporaries. Margulisbacteria were named for Lynn Margulis, the main proponent of the significance of endosymbiosis in evolution of eukaryotes, and Saganbacteria were named for Carl Sagan, a renowned science popularizer and communicator (and at one time, the spouse of Lynn Margulis). The information was then used to predict the metabolic strategies applied by a common ancestor to all five lineages.
In the lab of UC Berkeley geomicrobiologist Jill Banfield, a longtime JGI collaborator, postdoctoral fellow Paula Matheus Carnevali was working with a group of metagenome-assembled genomes (MAGs) dubbed Margulisbacteria, and had found they were closely related to another group of MAGs later dubbed Saganbacteria. At the same time, working with researchers from the Bigelow Laboratory for Ocean Sciences, Microbial Genome Program head Tanja Woyke of the U.S. Department of Energy (DOE) Joint Genome Institute (JGI), a DOE Office of Science User Facility, and research scientist Frederik Schulz in Woyke’s Single Cells group had generated and analyzed single amplified genomes of Margulisbacteria from marine samples.
The research teams opted to collaborate on a single study, with Matheus Carnevali and Schulz sharing co-first authorship. Their data suggests that the shared common ancestor of all five bacterial lineages was an anaerobe revealed that the ancestor of all these groups may have been an anaerobe who relied on fermentative metabolism and hydrogenases. Click here to read the “Behind the Paper” blog post by Paula Matheus Carnevali.
References:
- Publication: Matheus Carnevali PB, Schulz F et al. Hydrogen-based metabolism as an ancestral trait in lineages sibling to the Cyanobacteria. Nat Commun. 2019 Jan 28. doi: 10.1038/s41467-018-08246-y.
- Paula Matheus Carnevali’s “Behind the Paper” blog post: “Margulisbacteria and Saganbacteria, the newly uncovered siblings of Cyanobacteria”