Researchers analysing the genomes of microorganisms living in shale and oil gas wells have found evidence of a genus – the biological rank above species – of bacteria that has never been seen before.

According to the study conducted by scientists from Ohio State University and their colleagues, the new genus – which has been named "Frackibacter" as a play on the word "fracking", or "hydraulic fracturing" – is one of 31 types of microbe found living inside two different fracking wells.

The results are published in the journal Nature Microbiology. After taking samples of fluids, the team found to their surprise that the microbial communities in the two separate wells studied were nearly identical, despite the fact that they were hundreds of miles apart and drilled into different types of shale rock formations.

"We think that the microbes in each well may form a self-sustaining ecosystem where they provide their own food sources," Kelly Wrighton, assistant professor of microbiology and biophysics at Ohio State, explained.

"Drilling the well and pumping in fracturing fluid creates the ecosystem, but the microbes adapt to their new environment in a way to sustain the system over long periods.

Fracking well bacteria
Epifluorescence microscope image of Halanaerobium bacteria cells - one of the bacteria species which Ohio State researchers and their partners have discovered thriving in hydraulic fracturing wells Michael Wilkins/Ohio State University

"We thought we might get some of the same types of bacteria, but the level of similarity was so high it was striking. That suggests that whatever's happening in these ecosystems is more influenced by the fracturing than the inherent differences in the shale," she said.

Most of the microbes the team found have been identified in other places before and likely came from the surface ponds that the fracking companies use to pump water into the wells. However, Wrighton thinks that Candidatus Frackibacter may be unique to hydraulic fracturing sites because of the special conditions that exist there. In bacterial nomenclature, "Candidatus", denotes that the bacteria in question has not been studied as an isolated organism in a lab culture.

Where Frackibacter came from is still unclear, although the researchers suggest it could have been living in the rock before drilling began. So far, it has prospered alongside the microbes from the surface in sustainable ecosystems which have lasted almost a year.