Resistance, it seems, is futile, at least when it comes to the microbes that are captured and assimilated into others organisms by genetic transports – now dubbed ‘Borgs’ after the famous Star Trek villains.
The Borg are a fictional species that have terrorised TV screens since the late eighties. In the Star Trek serials, they conquered and incorporated the ‘biological distinctiveness’ of vanquished opponents into their own.
These assimilatory properties have inspired the naming of specialised DNA ‘packages’ that exist within Methanopereden microbes – tiny archaea (a separate domain of life to single-cellular bacteria and multicellular eukaryotes), which break down methane in soils, groundwater and the atmosphere to support their metabolism.
While studying the structure of a Methanopereden sample taken from a Californian wetland, Australian-born Dr Jill Banfield and her team from Lawrence Berkeley National Laboratory in the US discovered the microbes contained a new type of extra-chromosomal element (ECE), which are DNA packages that transfer genes between archaea, bacteria and viruses.
This process of gene transfer allows organisms to assimilate beneficial genetic characteristics that can be passed to their offspring during cell division. Gene transfer is a common phenomenon among single-celled organisms, however further study of the Methanopereden samples found 19 new ECEs, which the researchers believe contain the genes of entirely different microbes consumed by these archaea.
But it’s the way these ECE’s work to assimilate the genetic information of other organisms into their host archaea that has inspired the Banfield team to name them after the interstellar villains.
These borgs help their hosts eat methane
The Borg ECEs may have existed alongside Methanopereden throughout their existence, transporting genetic information to bestow competitive advantages. In particular, it appears these Borgs enhance the ability of their host cells to convert methane into energy – a process called chemosynthesis.
The distinct genetic information assimilated by Borg likely codes for unique variants of the proteins Methanoperedens usually produce as part of their normal functioning. These variant proteins could potentially confer “distinct biophysical and biochemical properties” on the cell.
“There is evidence that different types of Borgs sometimes coexist in the same host Methanopereden cell,” explains Banfield.
“This opens the possibility that Borgs could be spreading genes across lineages.”
The research team, whose study has been published in Nature, is now investigating how Borgs affect biological and geological processes, as well as analysing other data to see whether these structures exist in other unicellular organisms.
Some are also working to understand how Borg abundance and other methane-eaters influence seasonal changes in carbon gas within ecosystems.
Such are the methane consuming properties of Borg-boosted Methanopereden, the researchers suggest modified and cultivated specimens of the microbe could help address human-caused climate change by chewing through carbon emissions.
“Imagine a single cell that has the ability to consume methane,” says study co-author Dr Kenneth Williams.
“Now you add genetic elements within that cell that can consume methane in parallel and also add genetic elements that give the cell higher capacity.
“It basically creates a condition for methane consumption on steroids, if you will.”