Exotic combinations of complementary genes, called “borg” DNA, appear to energize their microbes, giving them an uncanny ability to metabolize substances in their environment faster than their competitors.
By learning more about how organisms use these unusual bundles of extrachromosomal information, researchers hope to find new ways to create life to drastically cut methane emissions.
After a study published last year, the researchers continued to analyze the diversity of methane-eating microbial sequences in these unusual genetic repositories to learn more about the evolution of life.
Named after the Star Trek aliens who devour other beings into the collective cellular brain, these enigmatic pieces of DNA perform a similar trick by absorbing beneficial genes from many different organisms over long periods of time.
These genes were found in a methane-consuming microbe called Methanoperedens, and they seem to have evolved over thousands of years to enhance the body’s ability to absorb methane.
“Imagine a single cell that can consume methane,” says ecologist Kenneth Williams of the Lawrence Berkeley National Laboratory in California. “Now you add genetic elements inside that cell that can consume methane in parallel, and also add genetic elements that make the cell larger containers.”
Scientists believe that the Borg are a form of DNA known as an extrachromosomal element (ECE). These bundles of genetic material are located outside the body’s chromosomes and are equipped with tools that allow genetic representation.
Unlike other ECEs, Borg have a linear rather than a circular structure. It’s also much longer than usual. In samples of underground soils, aquifers and riverbeds, the team found 19 different Borg ECEs, including four complete sequences.
Through extended genome analysis, it has been found that the Borg correspond to many of the methane metabolism genes in the methanotransporters themselves. Indeed, some Borg have all the mechanisms necessary to absorb methane on their own, provided they are inside a cell capable of expressing Borg genes.
Scientists speculate that the Borg may be the remains of fragments of a wide variety of microbes that are ingested by Methanoperedens, although not every Methanoperedens microbe contains Borg. One explanation for this is that the Borg act as repositories of metabolic genes that are only needed at certain times – for example, when there is a lot of methane around.
This means that some Methanoperedens microbes may exceed their natural ability to consume methane due to the presence of the Borg. And there is still a lot to be unraveled regarding these wonderful pieces of DNA.
“There is evidence that different types of Borg sometimes coexist in the same host cell, Methanopreredens. This opens up the possibility that the Borg may be spreading genes between bloodlines,” says ecologist Gillian Banfield of the University of California at Berkeley.
Researchers are now looking more closely at how the Borg might influence biological processes (in how cells develop) and geological processes (in how extra methane is captured from the environment).
Field work is being done in parallel with laboratory analysis to learn more about how these unusual Borg work and trace back a history that could stretch back billions of years.
The study is published in the journal Nature.