The preprint’s authors analysed DNA from mud in Prof Jill Banfield’s back garden (lab head and corresponding author). By digging deep (over 1m) into the soil from a springtime pond, the researchers probed for DNA associated with archaea, a type of microorganism that lives in low-oxygen environments. To their surprise, they found a previously unseen linear chromosome, a finding that they named Borgs.
Reconstructing the Borg DNA using short read sequencing resulted in a ~1 million base pair chromosome. This is a long sequence for a previously unknown DNA sequence. After identifying the Borg sequence and studying its characteristics, they also looked within public data to see if any Borgs could be retroactively identified in existing data.
Sure enough, the authors found 23 sequences that could be Borgs including samples from another site in California as well as groundwater samples in Colorado. Comparing the commonalities between the identified sites, Borg sequences appear to co-occur wherever Methanoperedens exist.
Methanoperedens is an archaeon that breaks down (oxidizes) methane. This led the authors to suspect that Borgs play a role in methane processing, perhaps boosting Methanoperedens’ ability to oxidize methane, a potent greenhouse gas. Not much more is understood about Borgs at this time. If the results can be independently replicated, the authors hope that understanding Borgs will play an important role in the management of climate change.